Re: [time-nuts] Affordable PoE 6-digit time displays?
Maybe not exactly, but I use an app on an old Android cell phone as my UTC wall clock. Large characters in horizontal mode; NTP via WiFi. Sent from BlueMail On Jun 14, 2018, 20:15, at 20:15, David Andersen wrote: >I'd hoped that ebay or aliexpress would yield a bounty given how >seemingly >simple these are, but I'm drawing a blank (and finding a lot of $300+ >new >options). Anyone have a favorite source for either flat wall-mount or >rackmount displays that will pull from an NTP/SNTP/whatever server? > >(if wall-mount, PoE is optimal). Used good. Cheap good. Looks good >next >to my random collection of antiquated time measurement gear provides >amusement value but isn't really critical. :-) > >Thanks! > > -Dave >___ >time-nuts mailing list -- time-nuts@febo.com >To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] nuts about position
On Sun, June 3, 2018 12:57 am, Mark Sims wrote: > Well, with a little prodding and help from Magnus, I now have the > Trimble devices outputting RINEX files. Is this applicable to a Thunderbolt, and would this improved position accuracy be expected to improve the time accuracy from a Thunderbolt compared to using the older Lady Heather 24 hour self survey method? Or is ionospheric noise the limiting factor so determining more accurate position doesn't really help? -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NEO-M8N vs. NEO-M8T
On Mon, May 21, 2018 2:23 pm, Gary E. Miller wrote: > I look forward to your patch! My GPSDO doesn't have sawtooth error, so limited interest for me. How much does one of those u-blox modules cost? How would you tell if it made the gpsd performance better? I think that question came up a couple of weeks ago, most of the ways to check time stability involve hardware test equipment logging electrical signals, and there isn't a good way to get an electrical signal generated cleanly from the gpsd software clock. Is there a way to have a timestamp log from another instance of a PPS driver (another meaning the first instance is the one in use by ntpd)? So you could have a PPS driver log timestamps from a really high quality input signal, such that any variation in the timestamps was due to the clock variation and not from the input signal, and then see if the variation in timestamps was less after adding sawtooth correction to gpsd. That's the only idea I can up up with off the top of my head to check whether such a patch would actually improve the clock estimate noticeably. In essence this is like trying to build a GPSDO without being able to see the output of the oscillator directly, so the normal approach to measuring stability with TICC, counters, phase noise analyzers, etc. doesn't really work. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NEO-M8N vs. NEO-M8T
On Mon, May 21, 2018 1:52 pm, Chris Caudle wrote: > On Mon, May 21, 2018 1:19 pm, Gary E. Miller wrote: >> Now, how to I tell the Linux kernel to apply that correction? > > Have the PPS driver accept the correction before logging the PPS > timestamp. Or just have the PPS driver log the raw timestamp, then have the PLL engine in ntpd incorporate the corrections into the math of the control loop. Presumably ntpd will be getting the information passed in from gpsd, so the clock control daemon should have the correction information in plenty of time before the next PPS pulse gets logged. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NEO-M8N vs. NEO-M8T
On Mon, May 21, 2018 1:19 pm, Gary E. Miller wrote: > Now, how to I tell the Linux kernel to apply that correction? Have the PPS driver accept the correction before logging the PPS timestamp. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] â NEO-M8N vs. NEO-M8T
On Sun, May 20, 2018 9:23 pm, Gary E. Miller wrote: > I do not see the keyword 'sawtooth' in the u-blox 8 doc. Can I buy a > clue? Sawtooth is what it looks like when you plot the quantization error of the PPS output, the documentation will just refer to it as quantization error. Referencing this doc (not sure it is the exact match for your model) https://www.u-blox.com/sites/default/files/products/documents/u-blox8-M8_ReceiverDescrProtSpec_%28UBX-13003221%29_Public.pdf 18.1 Introduction u-blox receivers include a time pulse function providing clock pulses with configurable duration and frequency. The time pulse function can be configured using the UBX-CFG-TP5 message. The UBX-TIM-TP message provides time information for the next pulse, time source and the quantization error of the output pin The UBX-TIM-TP message is described in: 32.21.8.1 Time Pulse Timedata byte offset 8, name: qErr unit: ps Quantization error of time pulse (not supported for the FTS product variant). I believe that means you ready byte offset 8 of that message, and it tells you how many picoseconds the next PPS output is expected to be early or late compared to the nominally correct location of the PPS pulse. Inject that offset into the math for your software implemented PLL and you can cancel out that noise caused by the GPS clock used to generate the PPS being asynchronous to the GPS satellite clocks. This document has some nice graphs of sawtooth shaped quantization errors, just search for sawtooth: https://ivscc.gsfc.nasa.gov/meetings/tow2011/Hambly.Sem.pdf -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] âNEO-M8N vs. NEO-M8T
On Sun, May 20, 2018 9:06 pm, Gary E. Miller wrote: >> Cranking sawtooth correction into your data will move >> the line down most of the way to the "JLâ" line. > > Except that requires a post process step, so not useful for real time. No, it can be used for real time, that is how GPSDO control loops back out the effects of sawtooth error so it does not add additional unnecessary noise into the control loops for the clean up oscillator. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] nuts about position (cheap receiver)
On Wed, May 2, 2018 11:36 pm, Mark Sims wrote: > have Heather do all the receiver configuring, data > capture, and RINEX making... I have been following along with the update messages, and this seems like really cool improvements to the underlying infrastructure pieces that a lot of us use (Lady Heather, support for more GPS modules, etc.), but I am having trouble putting all the pieces together. Having submitted the files to some post-processing server, do you only get back information showing your position to some small number of centimeters, or does it send back a stream of values showing the corrections to the full position + time equations at each reading? Can you use this data to go back to, for example, a stream of timestamps and add a correction factor to the timestamps to get improved time accuracy on historical data? -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TCVCXO Adjustment
On Sat, April 14, 2018 8:37 am, Bob kb8tq wrote: > big an issue as the TCXO. If it's a single location and the time is > arbitrary, then maybe not so big a deal. > If it's all arbitrary why worry about drift? > > GPS on the board looks like a good thing to have to me The application is time stamping separate free running devices, in this case different video and audio recorders. So the absolute time is arbitrary, but all the devices in use have to agree on the rate of time progression for as long as they are being used together. The typical requirement is that all the free running devices have timecode which will be aligned within one video frame, so ca. 33ms, at the end of the time of use. So for example, you are making some kind of video, you put all the timecode devices together and get their time synchronized, at which point they get separated and connected to various audio and video recording devices to output a timecode signal that the video and audio devices record along with their primary recordings, so that later you can line up the recordings from different machines and match same recording from different locations, angles, etc. and know they were from the same time. You want the last work of the day to still be synchronized to within closer than 33ms, so the maximum time you want to be able to work without getting your timecode generators back together to synchronize defines your drift rate which defines your acceptable accuracy. >From common specifications it seems that the commercial products converged on 24 hours as the use time limit, so 33ms/24 hours -> 0.033s/86400s ~ 0.4ppm Yes, in principle you could use an arbitrary clock rate as well as an arbitrary starting time, but that could only work if all the devices were exactly the same rate, so if you have to adjust the devices anyway, and some may be coming from 3rd parties that you don't have access to prior to use, then the only practical approach is for everyone to calibrate their devices to standard rate. I'll let the original poster ponder on whether GPS on board is a good thing or not, but I think you cannot count on GPS being available in use (could be inside a steel building, or a steel reinforced concrete building, with no RF reception), so you would still need a local oscillator which could hold the rate tightly enough to guarantee less than 33ms of phase drift over the course of a day. Maybe you could relax that to "working day" and say it's only over 12 hours, not 24 hours. What I think makes this potentially interesting to time-nuts is that the time requirements are pretty loose by time-nuts standards, but potentially some of the tricks that people come up with for getting ns level accuracy on hobby budgets could be applied to this to find a way for non-nuts (or at least not-yet-nuts) to get started on a really low budget. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TCVCXO Adjustment
On Tue, April 10, 2018 8:12 pm, Bob kb8tq wrote: > Since your typical PC does not have anything in it that is accurate to 0.1 > ppm, you still need something as a reference to compare things to. > A GPS module or a GPSDO are probably the easiest things to get ahold of. Catching up on some of the time-nuts traffic, some of the messages about GPS API on phones make me wonder if a phone would not be a better option for a typical non-time-nut user than a PC. Setting up a GPS receiver with PPS output with a modern PC that does not have a RS232 port available can be pretty tricky (you would probably be starting with a bare circuit board rather than a nicely packaged GPS device for starters), so maybe a phone with GPS built in that lets you grab raw time data would be a better setup for a user with limited experience setting up time measurement systems. Or maybe a GPS Arduino shield and build a calibration system from a second Arduino. Multiple possibilities that are hard to rule out until the hard performance limits are defined. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TCVCXO Adjustment
On Tue, April 10, 2018 6:10 pm, Wayne Holder wrote: > which is spec'd at a frequency tolerance or +/- 1 PPM and a frequency > stability of 0.28 PPM and a yearly aging of +/- 1 PPM max/year which, to > me, seems pretty impressive for a part that costs about $8. Something like this MEMS oscillator may also be worth consideration: https://www.sitime.com/products/super-tcxo/sit5356 That page says the device is sampling now, so I have not seen one yet, but the datasheet claims +/- 0.1ppm over temperature, initial tolerance of 1ppm, 1 year aging of +/- 0.5ppm, and 20 year aging of +/- 1ppm. MEMS oscillators rely on fractional frequency PLL as an intrinsic part of the design, so if you get the right part number you just write a frequency update via I2C, so you would not need an external DAC. > I've been pondering how someone building the device > would be able to easily and reliably calibrate it. One of the big limitations in a commercial factory environment that you do not face with a user built or user calibrated device is that commercial test and calibration time is a cost incrementing by the minute. For a user calibration procedure you can take advantage of the fact that there are several time sources which are noisy on short time scales, but average out to low long term error. > I'm basing the design around the Arduino, so the device could, in theory, > use the USB Serial connection as a way to connect to a calibration program > running on a PC. I have a few idea on how to attempt to do this, but this > is new territory for me, so I'm asking for advice and/or thoughts on how > feasible this might be. Is this a crazy, impractical idea given that all > the builder will probably have available to perform the calibration is a > regular PC and an Internet connection, or is there a way to make it work? For a time-nuts class user the answers would be different, if you really want to assume nothing but a PC and Internet it seems like you would be limited to averaging external (i.e. off premise, contacted over the Internet) NTP servers for long-ish periods of time. Since the device you described is similar to a clock in that it just constantly outputs time information, it seems that in principle you would just need to read the timecode output from your device, compare that to a known reliable time source (which for a typical non-time-nut I assume would involve NTP), and average for long enough to build up confidence in the rate difference between the known time source and your device. Send down a command to your device to adjust the frequency by enough to negate the rate difference, then send down a command to update the current device time to jump over whatever time error accumulated. The amount of time you want to average (I think) just depends on how noisy you think your current time estimates are, and how much precision you want in the estimation of the rate differences. Noise in the current time of the calibration PC would typically be down to variations in network latency if using remote network time sources. Noise in retrieving the current time of the timecode device would be in USB latency variations if retrieving via USB (which would be on the order of the 1ms USB frame time). You might be able to get better data from the timecode device by just decoding the timecode audio stream in software. The only other option which comes to mind would be incorporating longwave radio receivers into the time setting in some way, but that would require differences for each geographical region, and I do not think would be any lower noise than network time for most users on modern Internet connections. Important to do up front will be to define specific performance limits you would like to hit, and minimum acceptable performance. I don't think you will be able to really evaluate feasibility until you put real numbers on your goals (initial accuracy, desired rate accuracy after x number of weeks, whether you want to always adjust rate and current time simultaneously, or if there are cases were averaging time to detect rate it too long so you just want to jam sync current time, temperature range over which the device has to maintain time, etc.). -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lady Heather BST command line question
Hello, Thank you Mark, I had not put the zero in front of /GMT/BST and it obviously needed that as it's now working fine, many thanks for the great software! on 01/04/2018 08:51 you wrote: > Ooops, that should have been /b=2 to select the European time zone rule! > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Best Regards, Chris Wilson. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Lady Heather BST command line question
01/04/2018 06:10 I am struggling to make LH show the time in British Summer Time. I can get it to show UTC, but not with the BST offfset. Could someone please give me the exact start up command line to add to the Windows properties box please? Will it then automatically revert to GMT at the end of the BST offset? Thanks! -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TV Signals as a frequency reference
When the transition to digital only happened, I happened to ask a ham friend who was chief engineer at the local Fox station what they were doing with all their gear. He said probably taking it to a hamfest. I said if you chuck your rubidium or cesium standard let me know. He started laughing and said we don’t have anything that precision, you’d be lucky for it to be a TCXO. Chris KD4PBJ > On Mar 31, 2018, at 9:46 AM, jimlux wrote: > > On 3/30/18 10:43 PM, Hal Murray wrote: >>> As noted earlier, color burst references were a big deal a long time ago. >> Thanks. I was fishing for something modern, maybe a bit clock out of the >> digital receiver. >> I'm assuming that the digital stream is locked to the carrier. That may not >> be correct. > Maybe locked, but probably not in a 'integer number of cycles per symbol' > sense, more in the "derived from the same master 10 MHz reference" sense. > > All stations use the same data rates, but have different carrier frequencies, > and the carrier frequencies are the same ones we've always had, which don't > necessarily have nice ratios between them. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Setting correct date on Trimble Thunderbolt receiver
On Mon, March 26, 2018 6:49 pm, Tom Van Baak wrote: > The bad news is that if you use the Trimble TSIP RS232 interface and if > you want the correct date & time then the software needs to be aware of > the 1024 week (19.6 year) epoch. This "GPS 1024 week rollover" issue Many people do not use the date directly, it is served to other machines via other software such as ntpd. You should be able to configure ntpd to add an appropriate offset such that the correct date is served. If using directly (e.g. a machine is logging data and communicating directly with the Tbolt to get date stamps) you would have to add the equivalent offset yourself. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Allan variance by sine-wave fitting
On Mon, February 26, 2018 2:29 pm, Tom Van Baak wrote: > BTW, a trick for blinking LED's -- use two of them out of phase: one that > the user sees on the front panel and one that is blacked out or hidden > inside. A flip-flop (Q and /Q) or even a set of inverters is all you need. > The current draw thus remains constant in spite of the blinking. You could also use a long-tail diff-pair, with the LED in the collector circuit of just one side of the pair. Only costs one extra transistor and a few resistors and then the current draw is (close to) constant whether the LED is on or off. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Team of physicists repeats tvb Project GREAT
On Wed, February 14, 2018 7:06 pm, jimlux wrote: > At substantially more expense, and with an experimental lattice clock, Does that schematic figure in the paper imply that the "transportable" strontium and ytterbium clocks are built into trailers instead of the traditional rack enclosure? Actually now that I look more closely it looks like maybe two trailers. Doesn't seem like something that Jim is going to be flying any time soon. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Does a frequency counter locked to GPS need to "warm up"?
08/02/2018 07:31 Does a frequency counter connected to a permanently running (Trimble Thunderbolt) GPS disciplined frequency standard need to warm up after switch on before readings settle? Just curious, thanks. -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Sick Trimble TBolt
> What are the markings of the devices close to the BNC connector? Just a guess based on some previous comments from Bob, you are probably looking for a logic gate, probably with an LC filter on the output. Could also be some kind of MMIC device, but gate with a filter seems like a good possibility. Probably SOIC device, shouldn't be too hard to replace. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Sick Trimble TBolt
On Tue, January 30, 2018 11:33 am, Richard Solomon wrote: > I noticed a spot that looks like it takes a PC mount SMA. Others have noted that the PCB appears to support multiple different footprint oscillators or input of an external oscillator. > Looking at the center pin, it looks like the output of the TCXO. > I plan to run a small coax from that to the BNC output connector. > Any thoughts or comments ? If the output buffer is not operating properly, then there is a high likelihood the broken output buffer will just drag down the output of the OCXO, which will prevent the entire device from operating. Even with the buffer disconnected you risk disrupting the operation of the GPS receiver when you connect and disconnect loads to the BNC connector (if the GPS receiver even keeps operating properly with a 50 Ohm load directly on the oscillator output). What are the markings of the devices close to the BNC connector? Don't forget to check the bottom of the PCB, there are a few devices there as well on some models, but I don't know if the layout is the same on all revisions. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More on SiLabs 5340
On Mon, January 29, 2018 2:38 pm, John Ackermann N8UR wrote: > The close-in phase noise is quite amazing, but the floor is much worse > than in free-run mode. That phase noise plot doesn't look quite right, what PLL bandwidth did you set? -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More on SiLabs 5340
On Mon, January 29, 2018 2:38 pm, John Ackermann N8UR wrote: > to do, though, was feed 10 MHz into the "Input 0" port which apparently > disciplines the free-running crystal. It doesn't discipline the crystal oscillator, the crystal oscillator is multiplied up and used as the clock to run a DDS block. The 10MHz signal you input is the reference input to a digital PLL, and the output of the PLL modifies the tuning word of the DDS. In free run mode it works similarly, but the tuning word never changes, the DDS control value is chosen based on assuming that the DDS clock is running exactly at nominal frequency. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Trimble Thunderbolt Issue
On Sat, January 27, 2018 9:47 am, J. L. Trantham wrote: > I remember an issue with another OCXO where the output coupling capacitor > connection failed and outputs were low. The thunderbolt uses the output of the OCXO for driving internal clocks, so likely the OCXO output is OK, but a buffer between the OCXO output and the connector is bad. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Slightly OT: interest in a four-output, ultra-low jitter, synthesizer block?
On Thu, January 25, 2018 3:08 pm, Robert LaJeunesse wrote: > but I'll second Bill's section about including the power > supply voltage regulator and bypassing. Many of the SiLabs devices have on chip regulators, some of those may be worth investigating. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] SI5328
On Mon, January 22, 2018 6:42 am, Hal Murray wrote: > Does anybody know what's in the DSPLL box? Basically a PLL implemented with some kind of DDS for the VCO and DSP for the loop filter. https://www.silabs.com/documents/public/white-papers/Silicon-Labs-Next-Generation-DSPLL-Technology-White-Paper---June-2015.pdf The DSP loop filter gives a really wide range of loop bandwidth, down to fractional Hz for some parts. Using a DDS for the VCO gives a lot of flexibility in output frequency selection, but means that there can be problems with spurs. Part of the SiLabs secret sauce is supposed to reduce spurs compared to a simpler NCO implementation, but I don't think you can eliminate spurs entirely with any kind of DDS based design. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??
Hello Bruce, Sorry, this went to you direct as well, in error. Thanks for the very fast reply! Would it be possible to use one of these frequency multiplier IC's? Sounds simpler, but maybe there are down sides? http://uk.farnell.com/on-semiconductor/nb3n502dg/pll-clock-multiplier-8soic/dp/2101849 on 08/01/2018 13:11 you wrote: > Divide the 10MHz by 2 and use a filter to extract the fifth > harmonic from the 5MHz square wave output. > Amplify the 25MHz output from the filter if required... > Bruce > On 09 January 2018 at 00:31 Chris Wilson wrote: > 08/01/2018 11:28 > Is there an easy way to get 25 or 27 MHz from my Trimble Thunderbolt > as a reference clock at 1v P to P square wave for a Si5351a > synthesizer chip please? I have the David Partridge divider board from > way back that is still going strong, but 25 MHz is not an option as it > divides only. Thanks, please keep replies to the level an idiot might > comprehend :) > -- > Best Regards, > Chris Wilson. > mailto: ch...@chriswilson.tv -- Best Regards, Chris Wilson. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??
08/01/2018 11:28 Is there an easy way to get 25 or 27 MHz from my Trimble Thunderbolt as a reference clock at 1v P to P square wave for a Si5351a synthesizer chip please? I have the David Partridge divider board from way back that is still going strong, but 25 MHz is not an option as it divides only. Thanks, please keep replies to the level an idiot might comprehend :) -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] accurate 60 hz reference chips/ckts
On Thu, December 14, 2017 8:39 pm, Tom Van Baak wrote: > One can determine the appropriate time constant by looking at the ADEV of > the two clocks It appears that the appropriate design would use a local oscillator which is stable to better than 10^-7 at 5 years and approximately 1200 days time constant. I would recommend using very low leakage capacitors in your RC filter. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference
On Sat, December 9, 2017 2:39 pm, Magnus Danielson wrote: > The standard acceleration is internationally agreed at 3rd CGPM in 1901 > to be 9.80665 m/s^2. So does that mean e.g. NIST and BIPM need to measure the acceleration at their respective locations to within parts in 10^17 or 10^18 in order to compare their frequency standards? That seems not practical. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference
There is a piece missing for me in the articles I have found on new atomic standards. This is what I (think I) do understand: Quantum properties of the atoms can be interrogated using various RF or optical means to servo the frequency of an oscillator (which could be a laser based optical oscillator). The international standard for frequency (based on time) is defined in terms of a theoretical condition of cesium atoms which cannot be perfectly achieved in practice, needing absolute zero temperature, gravity/acceleration equivalent exactly to mean sea level of earth, no magnetic perturbation, no interaction such as bouncing off of cavity walls, etc. New optical standards can achieve "accuracies" of parts in 10^16, verified by comparing multiple instances of the standards with each other, and if the standards are built correctly and the theory of operation is correct, the multiple separate pieces of equipment should agree in frequency output to within some parts in 10^x, where x has historically been around 15, but is now reaching toward 17. So far so good, but here is where I have a gap: I put "accuracies" in quotations above because as far as I understand you can actually compare consistency of center frequency or stability over periods of time between two instances of a particular type of atomic oscillator, but accuracy in the sense of comparing how closely the the output frequency matches the calculated theoretical output frequency (assuming that the operating mechanism is fully understood) is going to depend on having a reference for comparison that is as good or better than the new standard to be measured. That implies that the reference has systematic offset that is known to better than parts in 10^17, but that would require knowing the quantum properties of the atoms in use to that level, knowing the gravitational potential at your location to that level, knowing that the temperature dependence of the equipment was below that level, etc. How can anyone ever talk about accuracy in the terms of SI second definition for these new oscillators? Are they really using layman's shorthand, and they mean stability and consistency? Or are they really able to measure all the other factors well enough that they can actually mean accuracy in the sense of how the SI second definition calls out absolute zero, gravitational potential, etc.? -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Performance verification for time counters
On Wed, November 29, 2017 3:51 pm, Poul-Henning Kamp wrote: > While it is tempting and probably easiest to use a DDS style > generator, I recommend a synthesized one instead, to avoid > trouble with numeric spurs. Can you describe the distinction you are making between a synthesized generator, and a direct-digital synthesized generator? I do not understand what would be meant by a synthesizer which is not DDS. > The HP3336 with its outstanding level-control is a much > overlooked bargain for this kind of stuff. I looked for the manual, and it seems to have ROM feeding values to a DAC. Is that not DDS? -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] ublox NEO-M8T improved by insulated chamber?
On Wed, November 8, 2017 12:55 pm, Gary E. Miller wrote: > I knew about the errata, I left out that detail to see when someone > actually read my citation. OK, I don't want to quibble about versions, and whether the "latest version" is 200H or 200H including errata, but I think we both agree that the currently operating performance would be described by the rollup document, i.e. the offset information for GPS time to UTC time should be within 20ns 1 sigma, as opposed to the older 90 ns 1 sigma description. > So yes, UTC from a GPS is now 20 ns (one sigama). What I said about > +/- 13 ns being noise relative to the spec still applies. Yes, and at that point I think you have to start getting into more precise language about whether you care about worst case, average, or "typical" performance. One of the graphs that Tom referenced a day or two ago seemed to show that the typical performance was better than 20ns, so is 20ns a guaranteed performance, a desired performance level (and better than that is good), or the measured performance level? > Do you now see how measured GPS time/location can be very precise, but > UTC from a GPS less so? Have you read the entire 3.3.4? Yes, and I do not really understand the "1 sigma" description. Is the error really random? I'm not sure how the term 1 sigma applies to error distributions other than a Gaussian distribution, so what "20 ns at 1 sigma" really means moment to moment for the time value I get from a GPS receiver is not completely clear to me. At a simplistic level I would interpret that 66% of the PPS ticks are within 20ns of the "true" UTC tick, 33+% could be farther away than 20ns from "true" second tick. The general interest in GPS based time transfer covers a wide range of uses, so whether you actually care about absolute offset from UTC or not needs to be made more explicit in discussions about vaguely defined "performance." I think in earlier emails there was some confusion about what "performance" actually referenced, since in a lot of use cases a fixed error offset from UTC is less important than varying offset, some people just need a well defined second tick, so whether the position of those ticks is within 2ns, 20ns, or 200ns of nominal UTC may not matter at all. Other uses may care about UTC, so there is not necessarily a one size fits all single number for "performance" that everyone will agree with. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] ublox NEO-M8T improved by insulated chamber?
On Wed, November 8, 2017 10:45 am, Gary E. Miller wrote: > No one here has yet bothered to address the issues I raise > in Section 3.3.4. Sure they did. Why are you referencing the old version instead of the newer version that Leo Bodner provided the link to? https://www.gps.gov/technical/icwg/IRN-IS-200H-001+002+003_rollup.pdf "The NAV data contains the requisite data for relating GPS time to UTC. The accuracy of this data during the transmission interval shall be such that it relates GPS time (maintained by the MCS of the CS) to UTC (USNO) within 20 nanoseconds (one sigma). " -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] ublox NEO-M8T improved by insulated chamber?
On Tue, November 7, 2017 3:30 pm, Ole Petter Ronningen wrote: > Not knowing better, I would expect there to be diurnal effects due to the > ionospere being in the shade or not. I think that is generally true. > Anyway, the effect I am seeing is also very slowly drifting, see screenshot > of about 20 days of data below. Your pictures are not making it to the list, it seems the list server strips out inline images. Actually inline images would imply you are probably sending HTML messages and they are getting converted to plain text. You could try attaching the image as an attachment to a plain text message, that may get through to the list. Regarding the drifting, if you mean relative to the wall clock time, GPS to planet alignment shifts because of rotation of earth, so the GPS effects tend to align to around 23 hours, not 24 hours. Is that the drift you are seeing, or more than about an hour per day relative to solar time? -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Holdover, RTC for Pi as NTP GPS source
On Wed, November 1, 2017 7:16 pm, Jim Harman wrote: > The DS3231 has an 8 bit register that will change its frequency in > increments of about 0.1ppm. Thus you could discipline it to get its pps > aligned with your reference. That sounds like you just designed the worst GPSDO ever. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Holdover, RTC for Pi as NTP GPS source
On Thu, November 2, 2017 5:19 am, Hal Murray wrote: > I'd let the RTC free run, feed its PPS to a "clock" program, and then feed > the offset to ntpd via SHM. I would just get a GPS that doesn't shut off the PPS when it loses lock and that has a decent TCXO for the clock. Or just use a rubidium and call it close enough. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Oscillators and Ovens
On Wed, November 1, 2017 3:38 pm, Hal Murray wrote: > >> In general, OCXOs have crystals with high Q -> low phase noise, >> especially >> compared to a TCXO, which *can't* have high Q, or the temperature >> compensation circuit can't do it's work. > > I don't understand that. Why can't I build a high Q TCXO? Compensation implies pulling the frequency away from the natural resonance. High Q implies that the frequency cannot be pulled very far away from natural resonance. The two items are directly contradictory. -- Chris Caudle I don't need > to > change the compensation very fast. Are good crystals high enough Q that > it > would take too long? > > What's the time constant? I'd guess it's Q/freq, maybe with factors of > 2pi > or e or ??? > > That seems small relative to how fast temperature changes. (but maybe > fast > relative to FCC smearing or things like that) > > > -- > These are my opinions. I hate spam. > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Holdover, RTC for Pi as NTP GPS source
On Wed, November 1, 2017 3:17 pm, MLewis wrote: > hadn't got there yet Your RTC is not likely to be tightly synchronized to NTP time, so there is a high probability that trying to use RTC as a secondary time source will actually make the system worse than just riding through using the NTP estimate of the current system clock frequency. If ntpd will even use it as a secondary clock, and not reject it because it is too far off from the preferred GPS source. Is this system not connected to other NTP servers over the network? NTPsec does not work very well in the case of only one GPS device available to set time, that is documented as one of the use cases which NTPsec does not currently handle well. If there are no other servers available for comparison you will probably want to use chrony. If there are other servers available then trying to switch over to the RTC will definitely make your ntp server perform worse than just leaving well enough alone. -- Chris C ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Designing an embedded precision GPS time
On Tue, October 31, 2017 7:19 pm, MLewis wrote: > ...the "better" quality RTCs seem to be DS3231 based > How does one translate that into an expected 24 hour holdover? For the RTC, or for an NTP server? If the NTP server is running it will not make a difference, modern operating systems do not use the RTC for the system clock, only to get close to the correct time at startup. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Designing an embedded precision GPS time server
On Thu, October 26, 2017 7:38 pm, Denny Page wrote: > If you are going to do PTP with ptp4l, or NTP with Chrony, you are going > to want hardware timestamping support on the ethernet phy. Or the MAC. The processor used on BeagleBone Black has timestamping in the MAC. Not quite as accurate as stamping in the phy, but should be a relatively consistent fixed offset. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Designing an embedded precision GPS time server
On Thu, October 26, 2017 5:58 pm, Bob kb8tq wrote: > Why go to the green? Cheaper. > Just go with one of these Pocket Beagles I have > sitting here wondering what to do with them. Pocket Beagles do not have Ethernet. How are you going to make a network time server from a board with no network? > get two Pi Zeros for the pice of the Pocket Beagle. Lash an interface > onto any of them (just like the Green) and get going. I suppose you could connect a network interface of some kind using the USB, but I have never seen a USB network adapter with hardware timestamping. Possibly they exist, but I do not believe that a driver currently exists which could read the hardware timer on a USB interface, you would need to create the driver (probably after you created the hardware). -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Designing an embedded precision GPS time server
On Wed, October 25, 2017 7:53 pm, Nick Sayer via time-nuts wrote: > I am considering a new project based on its cousin, the ATSAME70. What is a reasonable cost target for that at the volumes you could produce? Coming up with something that is a better value than BeagleBone Black at any kind of hobby project volume seems difficult. The processor you mentioned has a Cortex-M7 at 300MHz. has a Cortex-A8 running at 1GHz plus a Cortex-M processor available as a coprocessor. Peripheral set is pretty comparable, and you can buy BBB at retail for $50 which gets you the faster higher class processor, 512MB of DRAM and 4GB of flash. It runs linux right out of the box so you basically power it on and have NTP running. > Anybody have any ideas or suggestions along these lines? On my list of projects to work on is a cape for BeagleBone Black that takes 10MHz and 1PPS inputs along with a couple of RS232 converters for the UARTs so you can connect a GPSDO to a BBB to make a time server. In my estimation that seemed like the best return on effort. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Designing an embedded precision GPS time server
On Thu, October 26, 2017 9:40 am, Bob kb8tq wrote: > Since time stamping hardware does exist for 1588, why not simply put the > effort into folding that into NTP? According to the Chrony project web page chronyd already includes support for that. See "NTP timestamping" section: https://chrony.tuxfamily.org/comparison.html -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NTP linked PC clock is slightly ahead of Lady Heather GPS time
Hello time-nuts folk, Thanks for all the replies, I see now that it is nothing to concern myself with, and my curiosity is satisfied, much appreciated, you are true time experts! :) Good to see Lady Heather continues to be updated, thanks Mark. on 12/10/2017 12:36 you wrote: > Lady Heather's screen clock ticks when the time message comes in > (which can be offset from the actual time in the message). Heather > applies a receiver type dependent adjustment to the time in the > message and then displays the time. If you enable the digital > millisecond clock you will see that the clock does not necessarily tick at > hh:mm:ss.000 > The next release of Heather has an audible tick clock mode where it > ticks at hh:mm:ss.000 This can be used to set your watch more accurately, > etc. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Best Regards, Chris Wilson. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NTP linked PC clock is slightly ahead of Lady Heather GPS time
Hello, According to that clock LH is lagging about 0.5 seconds behind... PC time matches it exactly, as close as the eye can tell. Thanks for the replies. on 11/10/2017 17:11 you wrote: > For those who are in Europe there is the PTB (Physikalisch-Technische > Bundesanstalt, the German Federal institute of Physics and Technology) > service to check the PC's time: > <https://uhr.ptb.de/> -- Best Regards, Chris Wilson. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] NTP linked PC clock is slightly ahead of Lady Heather GPS time
11/10/2017 12:24 Probably a simple answer, but I am curious as to why my PC clock which is set by NTP on Windows 7 64 bit OS is ahead of Lady Heather's time, locked to a Trimble Thunderbolt by about half a second (guesstimate..) I caught a screen shot of the discrepancy just now, it's at http://www.gatesgarth.com/time.jpg I use NTP for low signal WSPR transmissions and a second out isn't the end of the world, if indeed something IS out. More academic than problematic, thanks -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Better GPS coming to phones
On Wed, September 27, 2017 9:38 pm, Bill Hawkins wrote: > Sadly, it is not the phone users who will benefit. It is the advertisers > who use your location to send targeted ads. I doubt that knowing which side of the parking lot you are in will be of much interest to advertisers. It will help navigation apps with things like determining whether you are on the access road or already on the highway, or which of two parallel roads you are on. In a timing context, I would hope that having a more consistent solution to the position/time equation would reduce the PPS jitter. It would be really nice to see one of these low power, high precision receiver devices used in a Thunderbolt style design that locks the chipset clock to the derived clock to avoid hanging bridges to see if the 10x better precision in location solution could result in 10x lower PPS jitter. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] True Position GPSDP + Rb X72
On Wed, September 20, 2017 3:44 pm, Stephan Flo via time-nuts wrote: > I just wanted a 10 MHz sync for my test equipment that was calibrated. > May be the GPSDO is all I need. Even an undisciplined rubidium oscillator is going to be very close to nominal 10MHz. You have never stated your desired precision that I have seen. The X72 manual says that the output should be within 1E-9 in under 10 minutes, and within 5E-11 after 30 minutes. Does any of the equipment you use have finer precision than that? -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP-531xx calibrator nearing completion
On Fri, September 8, 2017 5:15 pm, Charles Steinmetz wrote: > Depending on your application and its tolerance for jitter/PN, you may > want to use a fast analog comparator to do the initial sine-square > conversion. I think there have been several discussions on squaring circuits, I was more interested in the XOR doubler. That seems like it might be pretty simple to implement since I will have power supplies for CMOS gates easily available. I don't remember seeing discussions on that technique. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP-531xx calibrator nearing completion
On Thu, September 7, 2017 10:56 am, Mark Sims wrote: > It takes a 10 MHz input, feeds it through a sine-to square converter > (using a biased CMOS gate) doubles it to 20 MHz using XOR gates, Could you send me a snip of what that looks like? Or a link to the schematic if you have it already. I need to take 10MHz in and was going to generate 24MHz with a PLL, but probably 20MHz will be acceptable, and I think just a couple of gates would work a lot better from a space and power layout perspective. If I need 50/50 duty cycle I would need to double again to 40MHz and use a flip-flop to divide by 2, right? Does the XOR circuit still work OK with a narrow duty cycle? thanks, Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon
I think that even with a rudimentary and incomplete knowledge of the road network one could detect spoofing a car navigation system. The car would show up inside buildings and farm fields and lakes. You'd see this even on a very poor map. If the spoofer moved the signal even 200 yards the match to the roads would be total rubbish and non sense. It would be detectable even using very old maps with many segments missing On Mon, Aug 14, 2017 at 3:10 PM, Ron Bean wrote: > >In a car it is even easier. The car nav system KNOWS it must be on a > >roadway. The car's ground track (positional history) must be on a road. > > That's assuming the GPS company keeps their maps up to date (it doesn't > matter how often you update the maps in the device if the company's maps > don't keep up with reality). New roads appear, old ones occasionally get > moved. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon
Detecting a spoof is not really so hard. What you need to redundancy. When the two navigation methods diverge then you know one of them is acting up. (that is broken or being spoofed or just buggy) On a ship you have magnetic compass and knot log and almost certainly gyros and all these are typically NMEA connected. Then of course there is a paper based backup. But just using the available electronics you could detect divergence. A large ship that is long enough could use two GPS receivers one at each end. The ship knows it's magnetic heading and the distance between the two GPS receivers. When the GPS solution is wrong the ship knows to ignore GPS.An attacker would have to spoof so that both receivers are moved the exact same direction and distance. I'mhaving some trouble seeing how that could be done. (not that it can't be done) But in any case the first method (divergence from expected location) would work eventually and not requires any extra hardware. In a car it is even easier. The car nav system KNOWS it must be on a roadway. The car's ground track (positional history) must be on a road. When this is no longer true the navigator can turn the screen red and say "invalid gps signal". I more sophisticated car such as a Tesla with autopilot sensors can do a more sophisticated form of visual navigation and compare the observed road type (multilane divided highway or residential) and it can notice when it crosses intersections. It should notice divergence from GPS more quickly can could fail back to dead reckoning with visual updates. Yes an expensive to develop software system but not science fiction either. In a way cars have it good because they know they can't drive though building. Commercial aircraft have even better data available that could be used to compare with GPS, Ground based radar being one but many on-board systems as well. In short it is REALLY HARD to spoof information a person can know from other sources. On Mon, Aug 14, 2017 at 11:29 AM, Bob kb8tq wrote: > HI > > Since multi path is a real issue in a mobile environment, defining what an > “abnormal” > change is could be quite tricky. A reasonable “spoof” would start with > feeding the correct > data and then slowly capture the target (still with correct data). Once he > is are “in charge” > signal wise, start doing whatever …. If you are talking about a ship, you > have *lots* of time. > > Bob > > > On Aug 14, 2017, at 1:40 PM, ken Schwieker > wrote: > > > > Wouldn't monitoring the received signal strength and noting any > non-normal increase (or decrease) level change indicate possible spoofing? > The spoofing station would have no way to know what the target's > > received signal strength would be. > > > > Ken S > > > > > > --- > > This email has been checked for viruses by AVG. > > http://www.avg.com > > > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > > and follow the instructions there. > > _______ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon
The trouble with spoofing location is that in theory every ship is using more than one method of navigation. They would notice their GPS is acting up and turn it off. I'm far from a professional but I've taken the six week class and I'm reasonably certain I could find a place on the other side of the pacific ocean with no GPS. The GPS is far easier to use and more accurate but no one uses just GPS alone, they alway compare several methods. On Mon, Aug 14, 2017 at 10:12 AM, Clint Jay wrote: > I guess it would depend on the level of infrastructure available to the > attacker, clock distribution is a reasonably well solved problem isn't it? > > There would, I suppose also be the issue of receiver swamping, you could > monitor received signal levels as it's my understanding that the signals > from the satellites are weak enough that they're indiscernible from noise > floor without some rather complex processing? > > Authentication via signing could be another feasible way to prevent > spoofing except we are potentially talking about interference from state > actors who may even be the very people who run one of the satellite > networks > > On 14 Aug 2017 5:51 pm, "Attila Kinali" wrote: > > > On Mon, 14 Aug 2017 12:09:43 -0400 > > Tim Shoppa wrote: > > > > > I think if you are only trying to spoof a single receiver it would be > > > possible to walk a spoofed time/space code in a way that time moved > > without > > > so obvious of a discontinuity. I'm sure there would be effects a > time-nut > > > could notice still. > > > > Not really. Unless you have a multi-antenna setup (see jim's email), > > you have nothing to compare the signal to. Even an ideal reference > > clock in your GPS receiver does not help, as the attacker could be > > tracking you in such a way that you will never see a discontinuity > > in time or position and that all the other sanity checks you do > > still don't show anything. > > > > With a two antenna setup, you can already check whether the phases > > add up to what you expect them to be, given your position relative > > to the satellites position. You do not need 3 antennas as a potential > > attacker can spoof the phase of some satellites correctly, but not > > of all at the same time. This at least gives you a spoof/no-spoof signal. > > > > With an antenna array you can do some masking of spoofers (ie placing > > a null where the spoofer comes from). But this increases the cost and > > complexity of the system super-linear with the number of antennas. > > Maybe one way to do it, would be to use a single receiver with a stable > > reference clock and switch between antennas in short succession. Ie > similar > > to how the early single channel GPS receivers worked, but for antennas > > instead of SVs. But I have no idea how easy/difficult this would be > > to do and how well it would work against spoofers. > > > > Attila Kinali > > -- > > It is upon moral qualities that a society is ultimately founded. All > > the prosperity and technological sophistication in the world is of no > > use without that foundation. > > -- Miss Matheson, The Diamond Age, Neil Stephenson > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > mailman/listinfo/time-nuts > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Trimble Thunderbolt no longer determines the correct date
On Thu, Aug 10, 2017 at 10:24 AM, Brad Dye wrote: > > I read here on the Time Nuts messages that some are considering: "some > in-line device that re-writes the serial data as it comes out of the > Thunderbolt” > An in-line device makes sense if you don't have control of whatever you have the T-Bolt plugged into. This would be the case in a cell tower. But if the T-Bolt is plugged into a computer in your own house, I'd think it would be far easier to modify the software your computer runs. LH and NTP are the only two most of us would run and both are open source and easy to change. Four of five lines of code, max. Building an inline device would be easy, even an Arduino could work but it would need more software and time to write it than a simple patch to NTP or LH. Patches are free, and thousands of people can use them just by downloading but an in-line device has to be built for each user. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TBolt and the Local News
On Thu, August 10, 2017 5:12 pm, Bob kb8tq wrote: > Next up is the comment that it took two weeks > and $27,000 to fix. I wonder if that was the cost to purchase new GPSDO units, or the cost to have Trimble dust off the old source code and make a special release for them? -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt question
Thanks everyone. This has given me a lot of things to check as I further investigate over the next few evenings. I'll let you know what I find. Chris > On Aug 5, 2017, at 3:07 PM, Charles Steinmetz wrote: > > Arthur wrote: > >> I’d say it would be an MMIC amp similar to this device [Avago MGA-87563] > > If a chip similar to the Avago part Arthur referenced is what is installed, > which seems plausible, the 0.749v on the RF input (Pin 3) is a fault and is > caused by an external source of voltage (3.417v) imposed on the RF output > (Pin 6) through the internal feedback resistor to Pin 3, attenuated by the > gate resistor. > > Avago says this particular chip needs to have 0vDC at Pins 3 and 6, so if the > connected parts would impose any DC voltage on those pins, external blocking > capacitors must be used on Pins 3 and 6. You might check to see if there are > blocking caps (at least at Pin 6), and if they are good. (Alternatively, the > internal output capacitor from Pin 6 back to the output FET source may be > bad.) > > Of course, don't expect a bad external cap to be the only other problem -- if > it is bad, the 6-pin amp may well be bad, as well as whatever is connected to > the other side of the cap. > > Best regards, > > Charles > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt question
Hi, I've changed the blown MMBT3904 in the antenna sense circuit and I still have no 5V to the antenna. I measure 0.5V DC on the F connector. There are two Murata filters (F2 and F3) on the RF path to the antenna. In between the two silver colored filters is a 6 lead SOT package marked 51A. The PCB silkscreen says Q13. I have measured the following voltages on this part: Pin 1= 0v Pin 2= 0v Pin 3= 0.749V Pin 4= 4.892v Pin 5= 0v Pin 6= 3.417v The trace from pin 3 of this part goes to the F2 filter and the output of F2 goes to the F connector. I'm getting 0.5V on the output of this filter. I'm suspecting this Q13 part may be bad but I'm not sure what the part is. Searching the net for 51A marking came up with a large 2 pin shottky which this isn't. Chris KD4PBJ > On Aug 4, 2017, at 5:27 PM, Chris Waldrup wrote: > > Thanks guys. > I've opened up my T bolt and noticed a SOT23 packaged part has the top blown > off. > The PPS BNC jack has U19 beside it. > The next part is blown. Could someone take a closeup of the five parts around > U19? > The intact parts are marked: > 5Dz > 1AM > and two 2Az parts. > > > Chris > >> On Aug 4, 2017, at 4:13 PM, Arthur Dent wrote: >> >> Actually that isn't my photo I linked to but one I just Googled. That is >> probably a board revision most people don't have but it was the first one >> I saw so I used it just to show that the GPS receiver is part of the >> only circuit board and not another easily replaceable board like in some >> other units. >> >> I just took a couple of photos of the later revision of the board for >> anyone interested in seeing what might be fried. In the photo of the >> top of the board the signal comes into a filter then to a 25db amp >> marked AM50002 by Macom. Above the filter near the input is where the >> decoupled +5VDC for the antenna is connected. If you are only reading >> 0.5VDC, if your're lucky it might only be the amp is fried and that >> could be an easy fix. If the 5VDC is ok with the amp input pin lifted, >> it might be the only problem. I wouldn't bet on it though. The 4031 I >> believe is a 1575.42 SAW filter >> >> The photo of the bottom of the receiver area shows a Sawtek filter and >> other parts. At the bottom of the photo is C460, a feedthrough capacitor >> and that might be where the receiver output is but where my Tbolts are >> working I don't feel the need to look into whether you could connect >> the output of a seperate GPS receiver there to make it work. >> >> I do have one Tbolt that has no oscillator. I brought the EFC and 10Mhz >> connections to SMA connectors on the back so I can test other oscillators >> or GPSDOs that don't have an easy way to monitor of graph the stability >> of those units and using Lady Heather gives me a good way to compare the >> graphs to ones I'm used to. You might possibly be able to replace the >> built-in receiver but it might be easier to buy a working Thunderbolt. >> >> >> http://i906.photobucket.com/albums/ac262/rjb1998/GPS%20top%201_zpslgxunnyw.jpg >> >> http://i906.photobucket.com/albums/ac262/rjb1998/GPS%20bottom%201_zpschvruppt.jpg >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Closeup photo of Thunderbolt PCB around U19 needed- found
Part is MMBT3904 > On Aug 4, 2017, at 5:39 PM, Chris Waldrup wrote: > > Sorry. Should have changed subject line before. Just changed it. > > The EEV blog link shows the transistors but it's too fuzzy to read SMT part > markings. If I can get a code I'll try and look it up online. > > Thank you. > > Chris > >> On Aug 4, 2017, at 5:27 PM, Chris Waldrup wrote: >> >> Thanks guys. >> I've opened up my T bolt and noticed a SOT23 packaged part has the top blown >> off. >> The PPS BNC jack has U19 beside it. >> The next part is blown. Could someone take a closeup of the five parts >> around U19? >> The intact parts are marked: >> 5Dz >> 1AM >> and two 2Az parts. >> >> >> Chris >> >>> On Aug 4, 2017, at 4:13 PM, Arthur Dent wrote: >>> >>> Actually that isn't my photo I linked to but one I just Googled. That is >>> probably a board revision most people don't have but it was the first one >>> I saw so I used it just to show that the GPS receiver is part of the >>> only circuit board and not another easily replaceable board like in some >>> other units. >>> >>> I just took a couple of photos of the later revision of the board for >>> anyone interested in seeing what might be fried. In the photo of the >>> top of the board the signal comes into a filter then to a 25db amp >>> marked AM50002 by Macom. Above the filter near the input is where the >>> decoupled +5VDC for the antenna is connected. If you are only reading >>> 0.5VDC, if your're lucky it might only be the amp is fried and that >>> could be an easy fix. If the 5VDC is ok with the amp input pin lifted, >>> it might be the only problem. I wouldn't bet on it though. The 4031 I >>> believe is a 1575.42 SAW filter >>> >>> The photo of the bottom of the receiver area shows a Sawtek filter and >>> other parts. At the bottom of the photo is C460, a feedthrough capacitor >>> and that might be where the receiver output is but where my Tbolts are >>> working I don't feel the need to look into whether you could connect >>> the output of a seperate GPS receiver there to make it work. >>> >>> I do have one Tbolt that has no oscillator. I brought the EFC and 10Mhz >>> connections to SMA connectors on the back so I can test other oscillators >>> or GPSDOs that don't have an easy way to monitor of graph the stability >>> of those units and using Lady Heather gives me a good way to compare the >>> graphs to ones I'm used to. You might possibly be able to replace the >>> built-in receiver but it might be easier to buy a working Thunderbolt. >>> >>> >>> http://i906.photobucket.com/albums/ac262/rjb1998/GPS%20top%201_zpslgxunnyw.jpg >>> >>> http://i906.photobucket.com/albums/ac262/rjb1998/GPS%20bottom%201_zpschvruppt.jpg >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Closeup photo of Thunderbolt PCB around U19 needed
Sorry. Should have changed subject line before. Just changed it. The EEV blog link shows the transistors but it's too fuzzy to read SMT part markings. If I can get a code I'll try and look it up online. Thank you. Chris > On Aug 4, 2017, at 5:27 PM, Chris Waldrup wrote: > > Thanks guys. > I've opened up my T bolt and noticed a SOT23 packaged part has the top blown > off. > The PPS BNC jack has U19 beside it. > The next part is blown. Could someone take a closeup of the five parts around > U19? > The intact parts are marked: > 5Dz > 1AM > and two 2Az parts. > > > Chris > >> On Aug 4, 2017, at 4:13 PM, Arthur Dent wrote: >> >> Actually that isn't my photo I linked to but one I just Googled. That is >> probably a board revision most people don't have but it was the first one >> I saw so I used it just to show that the GPS receiver is part of the >> only circuit board and not another easily replaceable board like in some >> other units. >> >> I just took a couple of photos of the later revision of the board for >> anyone interested in seeing what might be fried. In the photo of the >> top of the board the signal comes into a filter then to a 25db amp >> marked AM50002 by Macom. Above the filter near the input is where the >> decoupled +5VDC for the antenna is connected. If you are only reading >> 0.5VDC, if your're lucky it might only be the amp is fried and that >> could be an easy fix. If the 5VDC is ok with the amp input pin lifted, >> it might be the only problem. I wouldn't bet on it though. The 4031 I >> believe is a 1575.42 SAW filter >> >> The photo of the bottom of the receiver area shows a Sawtek filter and >> other parts. At the bottom of the photo is C460, a feedthrough capacitor >> and that might be where the receiver output is but where my Tbolts are >> working I don't feel the need to look into whether you could connect >> the output of a seperate GPS receiver there to make it work. >> >> I do have one Tbolt that has no oscillator. I brought the EFC and 10Mhz >> connections to SMA connectors on the back so I can test other oscillators >> or GPSDOs that don't have an easy way to monitor of graph the stability >> of those units and using Lady Heather gives me a good way to compare the >> graphs to ones I'm used to. You might possibly be able to replace the >> built-in receiver but it might be easier to buy a working Thunderbolt. >> >> >> http://i906.photobucket.com/albums/ac262/rjb1998/GPS%20top%201_zpslgxunnyw.jpg >> >> http://i906.photobucket.com/albums/ac262/rjb1998/GPS%20bottom%201_zpschvruppt.jpg >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt question
Thanks guys. I've opened up my T bolt and noticed a SOT23 packaged part has the top blown off. The PPS BNC jack has U19 beside it. The next part is blown. Could someone take a closeup of the five parts around U19? The intact parts are marked: 5Dz 1AM and two 2Az parts. Chris > On Aug 4, 2017, at 4:13 PM, Arthur Dent wrote: > > Actually that isn't my photo I linked to but one I just Googled. That is > probably a board revision most people don't have but it was the first one > I saw so I used it just to show that the GPS receiver is part of the > only circuit board and not another easily replaceable board like in some > other units. > > I just took a couple of photos of the later revision of the board for > anyone interested in seeing what might be fried. In the photo of the > top of the board the signal comes into a filter then to a 25db amp > marked AM50002 by Macom. Above the filter near the input is where the > decoupled +5VDC for the antenna is connected. If you are only reading > 0.5VDC, if your're lucky it might only be the amp is fried and that > could be an easy fix. If the 5VDC is ok with the amp input pin lifted, > it might be the only problem. I wouldn't bet on it though. The 4031 I > believe is a 1575.42 SAW filter > > The photo of the bottom of the receiver area shows a Sawtek filter and > other parts. At the bottom of the photo is C460, a feedthrough capacitor > and that might be where the receiver output is but where my Tbolts are > working I don't feel the need to look into whether you could connect > the output of a seperate GPS receiver there to make it work. > > I do have one Tbolt that has no oscillator. I brought the EFC and 10Mhz > connections to SMA connectors on the back so I can test other oscillators > or GPSDOs that don't have an easy way to monitor of graph the stability > of those units and using Lady Heather gives me a good way to compare the > graphs to ones I'm used to. You might possibly be able to replace the > built-in receiver but it might be easier to buy a working Thunderbolt. > > > http://i906.photobucket.com/albums/ac262/rjb1998/GPS%20top%201_zpslgxunnyw.jpg > > http://i906.photobucket.com/albums/ac262/rjb1998/GPS%20bottom%201_zpschvruppt.jpg > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Can Lady Heather set PC time directly from a TrimbleThunderbolt?
On Fri, August 4, 2017 9:39 am, Chris Wilson wrote: > Thanks to everyone for the replies, so basically would you say that > with a permanent internet connection I should forget using GPS time to > set the PC clock and just use Meinberg or NTP (which is what I am > currently using and seems to work just fine)? I think you asked the wrong question, so you got the question to the answer you asked and not what you wanted to know. You asked whether Lady Heather can set PC time, the answer is yes but it is a crude way to set the time. What you really wanted to know is how to get time from a GPS receiver into the PC, and the answer to that is that gpsd has a driver that can communicate with a Thunderbolt (Palisade driver), and gpsd also knows how to communicate with a Thunderbolt. So use ntp directly to communicate with the Thunderbolt. Lady Heather is an awesome program for doing lots of things with a Thunderbolt, but disciplining the system clock to follow the GPS receiver is not really one of those things. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Can Lady Heather set PC time directly from a TrimbleThunderbolt?
On Fri, Aug 4, 2017 at 7:39 AM, Chris Wilson wrote: > > Thanks to everyone for the replies, so basically would you say that > with a permanent internet connection I should forget using GPS time to > set the PC clock and just use Meinberg or NTP (which is what I am > currently using and seems to work just fine)? You'd be using the same NTP software in either case. The difference is it you were to add a GPS reference clock to the current setup. Even with GPS you's till want to keep the internet based reference clocks. Currently your PC clock might be accurate that the few milliseconds level. Adding a GPS receiver into the mix will improve accuracy to the tens of microseconds level. You'd gain abut two orders of magnitude over the current setup. Do you need this? I can think of uses for a highly accurate clock in amateur radio. Perhaps you are measuring propagation delay. Doing this 100 times more accurately might be helpful.On the other hand maybe you only need log files time stamps to be with a second or so of correct? When I got into this may application was pointing telescopes and measuring the light from variable stars.Usually you can start with you application and work backwards to place a requirement on time accuracy On the other hand this is a "time nuts" list and some people here just want the BEST they can get. I'm not a fan of Meinberg because of the way they market freely available software. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Can Lady Heather set PC time directly from a TrimbleThunderbolt?
Hello, on 04/08/2017 15:36 you wrote: > Answer to second question: For GMT time display set the time zone > name to GMT with a time zone offset of 0. (TZ keyboard command TZ > GMT, command line option /tx=GMT). > First question: Yes Heather can set your system clock (assuming > the program has access privileges to the change the clock. Check > out the TS keyboard command or /ts? command line options. The > clock setting routine is rather rude and crude. It just jams the > system clock with the receiver time on a once per minute/hour/day > interval or whenever the receiver and system clocks diverge by more > the "x" milliseconds. The main purpose of the time set feature is > for use when you don't have a net connection or NTP available. > The next version of Lady Heather has the ability to echo the > receiver data (in either native format or NMEA format) to another serial port > / IP address. > And for radio operations Heather has the ability to display the location in > Maidenhead format. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. Thanks to everyone for the replies, so basically would you say that with a permanent internet connection I should forget using GPS time to set the PC clock and just use Meinberg or NTP (which is what I am currently using and seems to work just fine)? -- Best Regards, Chris Wilson. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt question
Couldn't wait till morning on this as it was on my mind this evening. I unplugged the Thunderbolt from the wall and plugged it back in. Immediately the frequency counter attached went from 9.. to zero then when it was powered back up went to the other side of 10 MHz at 10.000 and "Disciplining" came up on the control program. I measured the voltage on the coax and it was 0.5V. So no voltage out to antenna. I do have one of those 6V max polyphasers but we did get some really close strikes recently. I've had to change the Oncore UT Plus receiver board once in my Datum Starloc II and it was easy. Hope this is a similar Motorola Oncore. I'll open it up tomorrow and see. I need to find a better source of the Oncore UT Plus modules rather than waiting for the Chinese slow boat. Chris > On Aug 3, 2017, at 10:21 PM, Chris Waldrup wrote: > > Thank you Didier. > I'll check tomorrow for further issues. > > Chris > >> On Aug 3, 2017, at 10:05 PM, Didier Juges wrote: >> >> "If the Thunderbolt loses satellites, does it still put out a 10 Mhz >> signal?" >> >> Yes of course. When that happens, the Thunderbolt is said to be in holdover. >> >>> On Aug 3, 2017 9:29 PM, "Chris Waldrup" wrote: >>> >>> Hi, >>> >>> I just noticed the laptop that is always connected to my Thunderbolt had a >>> yellow block under COM1 on the Tboltmon program where it normally is green. >>> Also the date up on the screen was in early July. Satellites were still >>> shown. >>> The counter I leave connected still shows a 10 Mhz output. >>> I reset the program and this time all fields are ??? and com not detected. >>> I had thought maybe the laptop hung up. >>> I'll look at my system tomorrow. I'm trying to do a divide and conquer. If >>> the Thunderbolt loses satellites, does it still put out a 10 Mhz signal? >>> >>> Thank you. >>> >>> Chris >>> KD4PBJ >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ >>> mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt question
Thank you Didier. I'll check tomorrow for further issues. Chris > On Aug 3, 2017, at 10:05 PM, Didier Juges wrote: > > "If the Thunderbolt loses satellites, does it still put out a 10 Mhz > signal?" > > Yes of course. When that happens, the Thunderbolt is said to be in holdover. > >> On Aug 3, 2017 9:29 PM, "Chris Waldrup" wrote: >> >> Hi, >> >> I just noticed the laptop that is always connected to my Thunderbolt had a >> yellow block under COM1 on the Tboltmon program where it normally is green. >> Also the date up on the screen was in early July. Satellites were still >> shown. >> The counter I leave connected still shows a 10 Mhz output. >> I reset the program and this time all fields are ??? and com not detected. >> I had thought maybe the laptop hung up. >> I'll look at my system tomorrow. I'm trying to do a divide and conquer. If >> the Thunderbolt loses satellites, does it still put out a 10 Mhz signal? >> >> Thank you. >> >> Chris >> KD4PBJ >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/time-nuts >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Thunderbolt question
Hi, I just noticed the laptop that is always connected to my Thunderbolt had a yellow block under COM1 on the Tboltmon program where it normally is green. Also the date up on the screen was in early July. Satellites were still shown. The counter I leave connected still shows a 10 Mhz output. I reset the program and this time all fields are ??? and com not detected. I had thought maybe the laptop hung up. I'll look at my system tomorrow. I'm trying to do a divide and conquer. If the Thunderbolt loses satellites, does it still put out a 10 Mhz signal? Thank you. Chris KD4PBJ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Can Lady Heather set PC time directly from a Trimble Thunderbolt?
This idea keeps coming up. "Jamming" the time from a GPS into a computer is NEVER the best idea. When you "jam" the time the PC internal clock moves in jerks and jumps where it will move forward and even backward. The only way that works well is to discipline the PC's clock using the same method you'd use to discipline the crystal inside A GPSDO.You compare the phase between the GPS and the local PC clock then adjust the RATE of the PC clock to keep the peas in sync. That is what NTP does. I say all of the above because this is a "timeouts" list. If you only care that the PC clock by "close enough" that the time printed on the screen matches your wristwatch then a 50 millisecond error is acceptable as that is about the limit of human perception.But it you are a "nut" and want each millisecond of time to be reasonably equal, that means with "tick" of the PC's clock to advance in time about the same amount then you can't "jam" the PC's clock from GPS. You will need to adjust the PC clock's RATE not the PC clock's PHASE. On Thu, Aug 3, 2017 at 6:54 AM, Chris Wilson wrote: > > > 03/08/2017 14:50 > > I use an NTP client to set my Windows 7 64 bit PC time for digital > mode amateur radio activities, but I was wondering if my Trimble > Thunderbolt and Lady Heather can do the same job? If it can, how do I > do it please, and can the PC show GMT and not UTC, and finally does > the date glitch affect this? Lady Heather communicates with the GPS > via a true serial port. Thanks! > > -- >Best Regards, >Chris Wilson. 2E0ILY > mailto: ch...@chriswilson.tv > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Can Lady Heather set PC time directly from a Trimble Thunderbolt?
03/08/2017 14:50 I use an NTP client to set my Windows 7 64 bit PC time for digital mode amateur radio activities, but I was wondering if my Trimble Thunderbolt and Lady Heather can do the same job? If it can, how do I do it please, and can the PC show GMT and not UTC, and finally does the date glitch affect this? Lady Heather communicates with the GPS via a true serial port. Thanks! -- Best Regards, Chris Wilson. 2E0ILY mailto: ch...@chriswilson.tv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local System Time Sync
You should be using NTP for that. Simply "syncing" the local clock to GPS is never the best thing to do. If you think about it 50% of the time the local clock would have to go backwards and 50% forwards. This means you could have the system time be at the same time twice or you have missing time intervals. The correct way is to adjust the RATE of the local clock so you never have missing or double time. This is exactly the same as building a GPSDO. Every adjustment period you compare there PHASE of the local clock to GPS then adjust the RATE if required. NTP does this. On Tue, Jul 25, 2017 at 7:45 PM, Lee - N2LEE via time-nuts < time-nuts@febo.com> wrote: > I have what I believe is a simply question. Especially for this > illustrious brain trust. :) > > How can I force Lady Heather to time sync the local computer system it is > interfaced to ? > > Isn’t this what the /ts[odhm] command accomplished or I am > misunderstanding ? > > - Thunderbolt is interfaced to a Mac laptop running LH5 > - Connection is USB to Serial cable (might be the issue because of no PPS) > - Turn off Internet NTP sync on laptop > - Purposely set laptop time 15 seconds ahead > - Enter / then after the dash(-) I enter tsm to sync system time every > minute. > > I thought this would force the system to sync ever minute with Thunderbolt > time. > But it doesn’t it. It never corrects the laptop time, it is always wrong. > > What am I missing here ? > > Thanks, > > Lee > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] DAC performance [WAS: Papers on timing for lunar laser ranging]
What about josephson standards? After all, this is "Time Nuts" and we are allowed to propose silly-complex solutions to simple problems if it improves performance even a little. But seriously I thought the issue of making a perfect voltage standard was solved because the Volt is defined to be whatever the Josephson array produces. Yes expensive because to runs at nearly absolute zero. On Sun, Jul 16, 2017 at 4:10 PM, Bob kb8tq wrote: > Hi > > > On Jul 16, 2017, at 6:33 PM, Richard (Rick) Karlquist < > rich...@karlquist.com> wrote: > > > > > > > > On 7/16/2017 1:51 PM, Bob kb8tq wrote: > >> Hi > >> One gotcha with any ADC or DAC is going to be the reference. There, you > are in the same > >> “get what you pay for” dilemma. Stable and noisy, can do. Quiet and not > very stable, can do. > >> Both stable and quiet, not so easy if you want it cheap. > >> Noise can also be the sigma delta ADC’s weak point. Even at slow rates, > some of them need > >> a lot of averages to quiet down. > > > > The reference initially used in the E1938A turned out to be too > noisy/unstable. It was non trivial to find an upgrade. The > > HP Smart Clocks of 20 years ago were limited in their performance > > by the reference used. > > > > Has there been much improvement in references in the intervening > > 20 years? > > They still don’t seem to have the hysteresis problem licked. Yes, you can > do an oversized reference > and take care of the issue. More or less that’s what you would have done > 20 years ago. > > Bob > > > > > > Rick N6RK > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] TAPR kit- Success!!!!!
Just sent this to in response to an off list response from a member but I wanted to share with the group. I'm now seeing at least 8 satellites with just the tiny patch antenna sitting out on a chair on my deck (not connected to my main time system antenna out in the back yard) Success! Thanks to all for the help. Chris > > Hi Francis, > > Well, I got home tonight and connected up the receiver to the PC and opened > Lady Heather. No com port detected. Closed and opened Trimble Tboltmon. > Nothing. Hyperterminal. Nothing. > I then downloaded WinOncore12 and went through receiver setup. It did a self > diagnosis and passed. I unplugged the antenna and reran and it said low > antenna current. So it must be talking. > I'm now in signal quality screen and seeing satellites! > The receiver must have been in some weird state and needed to be set up > again. I'll leave for a while then try Lady Heather again just to see what > will happen. > For some reason tonight, now the RX LED isn't on (it comes on if I unplug the > serial connector from the laptop) but now the TX is flashing. > Thanks for the help and encouragement. > > Chris > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt Monitor Kit by KO4BB
The Raspberry Pi idea is good because for your $100 it can do a few other tasks at the same time. It can run LH but also maybe she other services like NTP, a small web server and also a WiFi based backup server that backs up any notebook computers you have (it such a hassle to plug in an external drive to a notebook that few people do it. So I have mine do an hourly backup over WiFi.) I have a Pi3 on my desk right now and yes, it is more than powerful enough and would be under utilized even with a half dozen light weight servers running. So a $100 t-bolt monitor is rather expensive but if you can get four of five other functions at the same price, maybe worth it. On Mon, Jul 3, 2017 at 9:50 AM, Mark Sims wrote: > The K04BB device is a great little relatively inexpensive and compact > Thunderbolt monitor. > > Another option is to use a Raspberry PI and the 7" color LCD touchscreen > along with the latest Lady Heather code. I've added touchscreen support > and some optimizations to the screen code for better display on smaller > screens. The combo makes for a very nice package that shows pretty much > everything and lets you control the unit from the touchscreen. The PI + > touchscreen does cost around $100 though. I've seen some really nice > builds, such as Willis Hendly's, with the Tbolt, power supply, and > PI/touchscreen (I think he actually uses a Beaglebone) mounted in a box. > Perhaps he will do a post showing his implementation. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Problems with TAPR Oncore M12+ kit
I'm using a little 5V Trimble mag mount patch at the bench for testing. Chris > On Jul 4, 2017, at 12:02 PM, Gregory Beat wrote: > > Chris - > > I was not aware that you were having issues with the TAPR Experimenters Kit. > I am finishing a DIY GPS kit build from "assorted parts sources" for Jim > Pruitt. > Jim missed purchasing the TAPR kit in May 2017 (sold out before he ordered). > -- > I acquired ($) a Synergy SynPaQ/E carrier board with a dead M12+ receiver. > Since I happen to have a couple spare Oncore M12+ boards (inventory, > working), > it was just a matter of swapping those receiver boards. > -- > You need to be careful in selection of the GPS antenna, since there are a > wide variety on the surplus market: Passive (no pre-amp); Active with > different voltage requirements (12, 5, or 3.3 VDC) from GPS receiver. > At the electronics bench, I try to use 5 Volt antennas (or 3.3V that are 5v > tolerant) with similar GPS receivers (5V preferred). > > greg > w9gb > > Sent from iPad Air ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Problems with TAPR Oncore M12+ kit
Hi, Definitely RX LED on and not TXD. I'll look more into this tomorrow night when back at my bench. Chris > On Jul 4, 2017, at 12:02 PM, Gregory Beat wrote: > > Chris - > > I was not aware that you were having issues with the TAPR Experimenters Kit. > I am finishing a DIY GPS kit build from "assorted parts sources" for Jim > Pruitt. > Jim missed purchasing the TAPR kit in May 2017 (sold out before he ordered). > -- > I acquired ($) a Synergy SynPaQ/E carrier board with a dead M12+ receiver. > Since I happen to have a couple spare Oncore M12+ boards (inventory, > working), > it was just a matter of swapping those receiver boards. > -- > You need to be careful in selection of the GPS antenna, since there are a > wide variety on the surplus market: Passive (no pre-amp); Active with > different voltage requirements (12, 5, or 3.3 VDC) from GPS receiver. > At the electronics bench, I try to use 5 Volt antennas (or 3.3V that are 5v > tolerant) with similar GPS receivers (5V preferred). > > greg > w9gb > > Sent from iPad Air ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Problems with TAPR Oncore M12+ kit
Has anyone else received a unit they can't get to work? I got my unit finally boxed up a few weeks back. The PPS LED flashes and power LED and RXD LED's light but the TxD doesn't. I've ordered replacement MAX chips and 74ACT04 chips from Digi-Key but this didn't solve the problem. As a next step I've found a Oncore M12 board on eBay coming from China and this should come in a few weeks. No serial communications unfortunately. I've also tried swapping pins 2 and 3 on the DB9 just in case RX and TX were swapped (although I had originally built the cable as per the schematic with the kit) but still no luck. Thanks for any comments. Chris KD4PBJ > On Apr 29, 2017, at 11:10 AM, Chris Albertson > wrote: > > On this product people are going to want holes drilled and I think a "D" > shape hole for the DB type connector. The holes would allow easy clamping > but in a two step operation.If I were making these I'd first clamp the > stock over a pair of 123 blocks, mill the holes, then after I hade a batch > of these made, hole the holes to hold the part a fixture and then mill the > edges. > > But that said, I could make a pair of these by hand with hack saw, file and > drill press in about 15 minutes. > > > >> On Fri, Apr 28, 2017 at 1:41 PM, Jerry Hancock wrote: >> >> >> Generally, the way I mill plates such as these is I surface a piece of >> scrap and then glue (using superglue) the stock down onto the scrap. I can >> then machine around the edges without worrying about clamping. With >> pockets though, the torque even when ramping down might break the part >> loose. >> > > -- > > Chris Albertson > Redondo Beach, California > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PI Zero W LED Desktop Clock with 10ths of Seconds / NTP disciplined
There already exists an NTP for ESP8266. At least a simple one. Look over on GitHub. On Sun, Jul 2, 2017 at 5:27 AM, Tim Shoppa wrote: > I have been thinking about doing similar with an ESP8266 controller -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Power connectors continued
These expensive and exotic connectors are nice but are over kill for most projects which live their entire lives on a lab bench and never fly to Mars or even Low Earth Orbit. I found out about "GX" style connectors a while back. They are multi-pin circular connectors with screw down locking rings with from 2 to 8 poles and size either 12mm or 16mm diameter They are not suitable for use on airplanes or the like but good enough for machine tools and any hobby project that needs straight (no coax) pins that are rated to 5 amps continuous. The really good part is the cost. About $1 per mated pair. Find them on eBay searching for gx16 for the 16mm version of gx12 for the smaller one. here is an example: http://www.ebay.com/itm/10-Pcs-8-Pin-16mm-GX16-8 <http://www.ebay.com/itm/10-Pcs-8-Pin-16mm-GX16-8-Aviation-Plug-Power-Chassis-Male-Female-Panel-Connector-/272702764391?hash=item3f7e59f567:g:UA8AAOSwi7RZNQDE> I think these win the bang per buck contest. For a buck each, these are not machined from brass, I think molded pot metal and chromed. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPScon running on Raspberry Pi 3b
On Sun, Jun 25, 2017 at 3:04 PM, Mark Sims wrote: > Heather's configuration priority is to process: hard coded defaults, > then the config file, and finally the command line options. This lets you > set your preferred settings in the config file and then override your > config file options from the command line. > If that is the desired behavior and I think it is reasonable and what most people would expect, then the correct implementation of that behavior is to NOT ACT on any config setting until the command line options are read. Or in general never act on an instruction that might be overridden So the bug reported below seems to be a bug. > > > > > When I ran it with ./heather -4u, it first told me that it was unable to > open /dev/ttyUSB0 and > then told me it was unable to open /dev/ttyUSB3. This is probably due to > the > configuration file containing "-1u", but if that option is given on the > command line then the configuration file value should be ignored - or at > the > least it should be tried after the command line option. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Latest Lady Heather
Any chance of this getting hosted in say Giithub? If people arguing to to contribute changes having each contributor hold his own changes is not what that call "best practice". If you make it easy enough by using git, you will see more contributions by users. On Sun, Jun 25, 2017 at 1:43 PM, Wes wrote: > I asked about this before but got no response. > > I know of John Miles' site where I downloaded v5 but I've seen a post by > Mark Sims about further enhancements and wonder where I might get the > latest. > > Mark seems to have an "unlisted number." > > Thanks, > > Wes > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)
You are correct about 9V batteries. A 10A short is about 90 Watts. But have you seen the specs on a LiPo Battery? I have a 18 volt nominal 8,000 mAH LiPo battery that is rated "40C". This battery is safe and within design limits to discharge at 40 x 8,000 mA. Yes, taking 320 amps out of the battery is acceptable, the battery is designed for that. The battery can continuously supply 5.7 Kilowatts over 2 times more power then can a standard AC mains wall outlet. Of course at that rate it runs out of power in roughly one minute. But you can do a LOT in one minute. When you short the leads you get a LOT more than 320 amps A battery like that costs only about $50 today so they are available to almost anyone who wants one. > (1) A common 9V (NEDA1604 style) battery should never be left where it > might contact a metal short, and should never be left in a pocket. I > knew better, but temporarily slipped an alkaline 9V battery into a > trouser pocket, where it was shorted by my keys and became extremely hot > very rapidly. The peak current might reach 10 A (depending on the > battery chemistry and how it's shorted), so the battery heats up very > rapidly! -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPScon running on Raspberry Pi 3b
I've got a Pi3 here on my desk. I only see one UART that connects to GPIO pins. But it turns out if you actually need to use serial you use the USB to serial dongles. If you need four serial ports use four dongles. That is just the way the Pi3 is. You can level the 3.3 volt serial port but then you are into a MAX chip and some passives or maybe just a couple transistors but the =USB-Serial dingle is easier then level shifting. If you want a Pi-like device that is better for real-time embedded use look at the Beagle Bone Black. But it was limited CPU and RAM compared to Pi3 but better IO. If you are building a NTP server, look at the Pi Zero version 1.3. $5 each. On Thu, Jun 22, 2017 at 7:51 PM, Orin Eman wrote: > On Thu, Jun 22, 2017 at 5:36 PM, Mark Sims wrote: > > > > > The PI does have a couple of logic level serial ports on the expansion > > connector you can connect a level shifter two. One port is normally the > > Linux serial console which you can configure to be a general purpose -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Power connectors continued
I think they call these "16mm aviation plugs" in the CNC machine tool world. They are common for connecting servo or stepper motors to their controllers. they have any number of poles from 2 to 6 or more and screw rings that secure them. Usually really good quality even from Chinese eBay vendors. But they are really used only for a cable to chassis and only up to a few amps. here is one <http://www.ebay.com/itm/5pcs-Aviation-Plug-4-Pin-16mm-GX16-4-Metal-Male-Female-Panel-Connector-New/172271528592?_trksid=p2047675.c19.m1982&_trkparms=aid%3D888007%26algo%3DDISC.MBE%26ao%3D1%26asc%3D44840%26meid%3D1f63ff61ed134f628c9629d26b2690b1%26pid%3D19%26rk%3D1%26rkt%3D1%26sd%3D281469838889> Why so many connecter types? So you don't cross stuff up. Power poles are great for low-tech 12 volt buss systems that don't need any kind of engineering and are tolerant of connecting "anything to anything." Amateur radios and lead acid batteries are OK. Not good for high tech battery or their chargers or loads. Th XT60 or if you need 90 amps, the XT90 is ok because it is gendered and you can't accidentally connect two sources. The aviation type are perfect for cabling four or six lead motors. I would not use 3-pin XLR for anything but audio. Don't make it easy to connect line level audio to a battery. A really dumb idea was this guy, I heard this story secondhand. He used A/C extension cords for speaker cables because they work well for that purpose, but then someone plugged a speaker into a 120vac well outlet. I assume it made a load 60 Hz tone for a few cycles.Best to follow industry conventions because that is what people expect. Even though it would work well electrically, no one uses a mini-USB jack for Ethernet and for good reason On Thu, Jun 22, 2017 at 11:42 AM, Mark Spencer wrote: > Sorry if I have caused any un due confusion thru my perhaps incorrect use of the terms "cannon" and "XLR." > The green connector with 4 separate female contacts is what I perhaps in correctly referred to as a "cannon" connector. The silver connector with 3 separate female contacts was what I perhaps incorrectly referred to as a "XLR" connector. > > Both were in use in my lab powering time nuts gear. > > > > > > > > > > > > > Mark Spencer > > m...@alignedsolutions.com > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)
Get the "real ones" not the knock-off clones. Better plastic and better precision molding. There are lots of cheap ones on eBay. HobbyKing has the best prices for authentic, higher quality ones. Still only 80 cents. On Thu, Jun 22, 2017 at 11:15 AM, Brent wrote: > Never seen the XT60. Thanks for the heads up - looks promising - and cheap. > > Brent > > On Thu, Jun 22, 2017 at 12:48 PM, Chris Albertson > wrote: > >> One of the problems of power poles is they are expensive. Not a >> problem if you only need a few of them. I've been buying DC >> connectors by the bag full as I've working on some battery powered >> mobile robots I robot does not need many but for every finish one >> you've build maybe four breadboard systems and then you have the >> battery charging systems and the cables that connect battery chargers >> to power supplies. (LiPo battery charging is complex when you get into >> 18 volt 10 amp hour sizes. >> >> Power poles are also rather bulky. OK if the equipment is stationary >> but not good for something that flies or drives around where weight >> and volume matter a lot. >> >> I've standardized on XT60 type connectors These very compact and >> rated for 60 amps continuous. Much easier to assemble and they cost >> about 80 cents per mating pair.They are common in the electric >> power drone industry as battery connectors >> the XT60 is easy to use because they don't come apart. the metal pins >> are permanently molded into the shell, you simply solder the wires on. >> The shell is high temperate plastic and withstands even unskilled >> soldering. >> >> I did something stupid last might and assembled power distribution not >> as designed with a mosfet switch and diode in backwards then connected >> a high power density battery. I had an open flame along an entire run >> of #18 cable but finally the coper conductor failed (the metal >> vaporized) and the circuit opened and the flame stopped. I have some >> chared remains of wires and crunchy black melted plastic. But the >> XT60 connectors are still good. The metal parts inside are still >> shiny gold plated and the nylon shells are good as new, after cleaning >> the soot off. >> >> I was actually holding the connecter in my hand when the thing went >> off like a bomb, but just minor burns. Still amazed the connecter is >> fine after unsoldering the little stubs of burned wire from the pins. >> >> >> >> On Thu, Jun 22, 2017 at 12:19 AM, Tom Van Baak wrote: >> > Wes, Don, >> > >> > I am quite surprised at the negative reaction to Anderson Power Pole >> connectors. I have found them the best DC connector out there. I have used >> them for a decade or two for all my DC feeds and have never had a problem: >> in my home lab, my car, even for my laptop charger. They are inexpensive, >> reliable, genderless (hermaphroditic) and easy to crimp. I use them for my >> 5V, 12V, 24V, and 48V supplies as well as my DC backup systems. >> > >> > What on earth are you doing with them that causes them to disconnect? I >> mean, they are not meant for towing or lifting or rappelling. For critical >> applications there is a plastic gizmo that keeps them mated; or just use a >> square or figure 8 knot on the cables. >> > >> > /tvb >> > >> > ___ >> > time-nuts mailing list -- time-nuts@febo.com >> > To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/time-nuts >> > and follow the instructions there. >> >> >> >> -- >> >> Chris Albertson >> Redondo Beach, California >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/time-nuts >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How to love your Power Poles.
No, there are more problems. Being non-gendered that apply connections mistakes like connecting to power sources together. Could you imagine how bad it would be if all power connectors were not-gendered? then you could connect two wall AC mains outlet together. Kind of a problem if there were out of phase (US 120VAC wiring is like that) Bad enough that it allows tow DC power supplies to be connected. What is is good for is it you are in a hurry. non-genet connections were invented for firemen so after laying dow 300 feet of hose that NEVER find the have it backwards and have to flip a 300 foot hose end for end. Ive done this a few times with outdoor AC extension cords. There is an advantage to gendered connectors. Typically the source are female and you can't plug two outhouse together by mistake. If you need N-way connections yo make and test the power harness before hand. That said I do have some power pole cables. They work good for 12VDC lead acid battery type stuff. But NEVER use then for exotic battery chemistries. Fires are not good. and it WILL happen if you use PP on Lithium type batteries, an accident waiting to happen. On Thu, Jun 22, 2017 at 7:11 AM, James Robbins wrote: > I’ve used Power Poles for some years. I have a proper crimper intended for > PP. Color coding is very useful. > > I think the complaints about them are due to two things: (1) improper > crimping of the contacts and (2) heavy gauge wire. > > The PP15/30/45 use the same plastic housing while changing the size of the > contact. A wire gauge suitable for 30 to 45 amps is quite large physically > and puts a great deal of mechanical strain on the plastic connectors. So, > when such a gauge of wire moves (or doesn’t move), it tends to disconnect the > plastic housings. If the connections are from one set of wires to another, a > two prong plastic jumper plug can successfully hold the four connectors > together through the mating holes in the pair during movement. > > The problem is that when one set of connectors is mounted in a chassis, it is > often not really possible to use a two prong plug (or Ty-Wrap) to physically > hold them together. Move the chassis and if the wire doesn’t want to follow, > you get disconnected. > > Two solder lugs mounted to the chassis and a few small Ty-Wraps will fix most > of this “heavy wire” issue. > > Jim Robbins > N1JR > > PS: Make up a pair of PP with an LED to test your future PP builds. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)
One of the problems of power poles is they are expensive. Not a problem if you only need a few of them. I've been buying DC connectors by the bag full as I've working on some battery powered mobile robots I robot does not need many but for every finish one you've build maybe four breadboard systems and then you have the battery charging systems and the cables that connect battery chargers to power supplies. (LiPo battery charging is complex when you get into 18 volt 10 amp hour sizes. Power poles are also rather bulky. OK if the equipment is stationary but not good for something that flies or drives around where weight and volume matter a lot. I've standardized on XT60 type connectors These very compact and rated for 60 amps continuous. Much easier to assemble and they cost about 80 cents per mating pair.They are common in the electric power drone industry as battery connectors the XT60 is easy to use because they don't come apart. the metal pins are permanently molded into the shell, you simply solder the wires on. The shell is high temperate plastic and withstands even unskilled soldering. I did something stupid last might and assembled power distribution not as designed with a mosfet switch and diode in backwards then connected a high power density battery. I had an open flame along an entire run of #18 cable but finally the coper conductor failed (the metal vaporized) and the circuit opened and the flame stopped. I have some chared remains of wires and crunchy black melted plastic. But the XT60 connectors are still good. The metal parts inside are still shiny gold plated and the nylon shells are good as new, after cleaning the soot off. I was actually holding the connecter in my hand when the thing went off like a bomb, but just minor burns. Still amazed the connecter is fine after unsoldering the little stubs of burned wire from the pins. On Thu, Jun 22, 2017 at 12:19 AM, Tom Van Baak wrote: > Wes, Don, > > I am quite surprised at the negative reaction to Anderson Power Pole > connectors. I have found them the best DC connector out there. I have used > them for a decade or two for all my DC feeds and have never had a problem: in > my home lab, my car, even for my laptop charger. They are inexpensive, > reliable, genderless (hermaphroditic) and easy to crimp. I use them for my > 5V, 12V, 24V, and 48V supplies as well as my DC backup systems. > > What on earth are you doing with them that causes them to disconnect? I mean, > they are not meant for towing or lifting or rappelling. For critical > applications there is a plastic gizmo that keeps them mated; or just use a > square or figure 8 knot on the cables. > > /tvb > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)
On Thu, June 22, 2017 7:40 am, Mike Seguin wrote: > For anything critical, I use these connector from the professional sound > industry. > http://www.neutrik.com/en/speakon/ Neutrik make a variant specifically created for power connections instead of speaker connections. I think they are essentially the same style design but with different color coding to make them stand out from speaker connections. I don't know if the contact plating may be different, or the spacing different so it can handle higher voltages. Ground mates first before the two power pins (three pin instead of the four pin Speakon). UL listed for up to 250V AC. http://www.neutrik.com/en/powercon-20a/ -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TruePosition on the Arduino
Yes, It is easy if you have an Arduino handy. Write a scratch to try EVERY address one at a time. Print the currently attempted address top the screen In fact there is a pre-written sketch in the IDE's I2C examples folder. You can run that and it will report what it finds. It just tries reads on every possible address. On Tue, Jun 20, 2017 at 6:02 PM, Tom Miller wrote: > Has anyone been able to get the Packrat software to work with a display? I > have been successful getting the Arduino board to initialize the > Trueposition board but can't get the display right. > > The problem seems to be getting the I2C addressing correct. There are > several 16x2 line displays available but they address at 0x20 to 0x27 and > 0x38 to 0x3F. Neither of these work. > > Since we do not have the source, is there any way to find out what address > is in use? > > Regards > > - Original Message - From: "Gregory Beat" > To: > Sent: Tuesday, June 06, 2017 8:44 PM > Subject: Re: [time-nuts] TruePosition on the Arduino > > >> Ben - >> I assume that you never received the Arduino "C code" >> written by Bruce, WA3YUE for the original project? >> >> Club's Powerpoint presentation indicated that source code was available. >> http://www.packratvhf.com/techinal.htm >> >> Packrat GPS Project (Gary, WA2OMY; Bruce, WA3YUE; George, KA3WXV) with >> TruePosition GPSDO and Arduino >> by The Mt. Airy VHF Radio Club "Pack Rats" (Southampton, PA). >> http://www.qsl.net/wa2omy/A%20Packrat%20GPS%20Receiver%20Project.pdf >> >> greg, w9gb >> == >>> >>> original message / digest < >> >> I'm getting to the point that once I've got the button logic working, I'll >> send out my source to anyone who wants to take a look at it or use it. >> I will stipulate one condition - you can't make too much fun of how poorly >> programmed it is. ;) >> thanks much and 73, >> ben, kd5byb >> == >> Sent from iPad Air >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPScon running on Raspberry Pi 3b
it looks to me like Olgierdhas a working INTEL linux os running on the Pi3. He installed Wine on the Intel Linux not on the ARM Linux It looks like maybe Michael has an ARM version of linux running native on the Pi3 Wine will not run on that If you need to run Wine, you need to fist have an INTEL lInux running. Remember "WINE= Wine Is Not an Emulaor" and it will not run Intel binaries on Arm. I'm skeptical it would be more then a stunt a triple stack of virtual environments. But if the final Windows app is not really doing anything with the CPU, maybe fast enough. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hints on PPS Buffer design...
Why 100R? If using a 74xxx logic part as the driver is has a maximum drive current. 100R limits current in case of a short to ground or 5V supply to only 50mA It is about the lowest value resister i'd want to use If you need 50 ohm output them go with an small RF amplifier or a transistors driver. These can drive a 50R load without burning up. On Sat, Jun 17, 2017 at 1:15 AM, Clay Autery wrote: > Trying to pin down a reasonably optimal buffer design for bringing PPS > out... I've looked at all the references, like the i3detroit.org site > et al. > > Of the few schematics and devices I see, most are using a hex inverter > (1 into the other 5 paralleled with series resistors for "balance" and > setting output impedance? > > Q: Why does everyone pick FIVE x 100 Ohm resistors? That's 20 Ohm out, > not counting the gate impedance on the hex inverter... > > Q2: Anyone have a reference to the math for choosing the resistors for > setting a 50 Ohm nominal out INCLUDING determining and including the > gate impedance of a particular part. > (Right now, I am going to use the TI SN74AC04 Hex Inverter) I saw a > refernence in the archive referring to a 4 gate setup using a different > part needing 187 Ohm resistors... thus I can only include that I need to > use something slightly more than 250 Ohms on a 5 gate parallel setup) > > Q3: It's only a 1Hz frequency, but is low inductance a desired trait of > the chosen resistors? > > I'm sure there are others... > > Thanks! > > -- > __ > Clay Autery, KY5G > MONTAC Enterprises > (318) 518-1389 > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS splitter
On Fri, Jun 16, 2017 at 8:54 PM, Clay Autery wrote: > This brings up some interesting questions: > > > I am assuming since this is a receive only situation, it will follow > approximately the same rules of physics that dealing with satellite > antenna installations. > And guess what? Satellite TV splitters work. They even have the answer to "how much attenuation" printed right on the splitter and they come with F type connecters you can use the recommended TV type antenna cable too. You can buy them with DC blockers too. All this stuff is low cost because it is mass produced by the billions Yes, it's 75 ohm not 50 and the splitters a 2+ GHz but it works just fine if your antenna has the right gain. The splitters don't high pass the signal.Trimble actually recommends using the 75 Ohm TV cable and supplies it with their kits. Sometimes a GPS receiver will raise an "Antenna Alarm" if it does not see a DC load but you can turn those off with a serial command -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TAPR GPS Experimenters Kit
Last night I measured the voltages on the serial lines with a DMM. The TXD coming from the GPS was a solid -5.9 V. The RxD was 0 V. Chris > On Jun 14, 2017, at 10:53 PM, Chris Waldrup wrote: > > Hi Greg, > > I'm using a 12 V 7 Ah gel cell for the power and have a small Trimble > magnetic puck antenna connected just for testing. > > Chris > >> On Jun 14, 2017, at 1:22 PM, Gregory Beat wrote: >> >> What is your DC power source? >> https://www.tapr.org/images/com-cbl.jpg >> >> I used pin 7 (Black, DC GND) and pin 8 (Red, +8 to +32 VDC) >> and old +12 VDC, 1 Amp Wall Wart for my build. >> >> greg >> w9gb >> >> Sent from iPad Air ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TAPR GPS Experimenters Kit
Hi Greg, I'm using a 12 V 7 Ah gel cell for the power and have a small Trimble magnetic puck antenna connected just for testing. Chris > On Jun 14, 2017, at 1:22 PM, Gregory Beat wrote: > > What is your DC power source? > https://www.tapr.org/images/com-cbl.jpg > > I used pin 7 (Black, DC GND) and pin 8 (Red, +8 to +32 VDC) > and old +12 VDC, 1 Amp Wall Wart for my build. > > greg > w9gb > > Sent from iPad Air ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TAPR GPS Experimenters Kit
Hi, I have my board packaged up and am trying to get it working. Last night I built the cable to split out serial, 1 PPS and power. My unit powers up, and the 1 PPS and RxD LEDs are flashing and the green power LED is solid on. However I can't get serial to work and the TxD LED isn't flashing. I verified the pinout of the cable I made with a DMM. Pins 2 and 3 are swapped between connectors so the RX is going to TX for each of the two lines and pin 5 ground is the same on both D sub 9 connectors. I have tried Lady Heather, Tboltmon, and even just pulling up hyperterminal and I'm getting nothing. My settings are COM1 9600 8-N-1 and I'm using a Dell laptop that has an actual serial port and am running XP. When I'm Thunderbolt Monitor program, the green TX LED icon on the screen flashes and when it does the RxD lights on the M12+. Just no TxD coming out of the M12+. Has anyone else had a problem with this? If so is it fixable? Thank you. Chris > On Jun 3, 2017, at 11:22 AM, Gregory Beat wrote: > > Jerry - > > I rarely use "raw" Oncore M12 commands these days, using one of the 3 common > PC programs: Lady Heather, TAC32/SynTAC, M12Oncore(old Moto pgm). > > How are you routing that 1 PPS signal? Does your front LED pulse? > I wire 1 PPS to the DCD pin (DE-9M, standard RS-232), TAC32 can be configured > for "which pin" (DE-9M) to sense that PPS signal. > This is why I prefer to use Mark Sims' Lady Heather or Rick Hambly's TAC32. > TAC32 program has a quick setting for config. receiver as Timing or > Navigation. > > IF you continue to have issues, perform the Hardware Reset (Lady Heather). > That will return your receiver to default factory with cleared settings. > > greg > --- > Greg, Funny. > Some of the Lucent boxes have been in strange places as well. > Can you please check your PPS to see if you get a signal when in that other > mode (where it needs at least one sat locked)? > > Sent from iPad Air > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Control Systems (was: uC ADC resolution)
On Sun, Jun 11, 2017 at 9:28 AM, Attila Kinali wrote: > Hi, > > > You are asking a lot of question regarding control systems. > But, there are no easy answers there. Especially if you want > to build it cheap. The cheaper you want to be the more you > need to know and understand the problem. > This has been my opinion for a LONG time. It is easy to come up with good solutions if to just throw money at the problem.So you see here people proposing just going top of the line all across but an engineer earns his money by comping up with cost effective solutions that meet all the stated requirements. This is my interest in mechanics too. Can a $200 3D printed plastic robot arm with poor absolute repeatability place an M6 screw into an M6 nut? Certainly not if it runs open loop. But what if you add visual feedback? Yes everything requires more expertise if you reduce the budget So you understand my questions are all like this: "If you back down from top of the line solution how does that effect real world performance?" No one answers. > > I suggest you reading an introductory text into control systems > like e.g. "Feedback Control of Dynamic Systems", by Franklin, Powell, > Emami-Naeini. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] uC ADC resolution (was: Poor man's oven)
On Sat, Jun 10, 2017 at 12:59 PM, Poul-Henning Kamp wrote: > > > Delta-Sigma strategies for spreading the noise-spectrum are > interesting, but will not save you if the required heater power > ends up being a small rational fraction (1/2, 1/3, 1/4 ...) of the > full scale. > How many output bits are required? Most uPs have quite a few digital output pins. Each pin could drive a heater resister. Values of the resisters organized by power of two. Again note the title (poor mans...) resisters cost almost zero. Even of driver transistors are needed you'd get change back from a dollar bill. The reason I ask "how many bits" is because the above is reasonable with 4 to 6 effective bits but not reasonable with 24 I say "effective" because we can dither the low order bits to gain maybe 6 effective bits form 4 real bits (we can filter the switching noise from a low frequency dither) -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] uC ADC resolution (was: Poor man's oven)
On Sat, Jun 10, 2017 at 11:33 AM, Magnus Danielson < mag...@rubidium.dyndns.org> wrote: > Hi, > > I was about to make this very point myself. The resolution of the ADC > needs to be higher than the limit you try to achieve. There is several ways > to reason about it, but one is that the system is a bit slugish you want to > have higher resolution in order to react of changes before they overshot > the limits you want to keep. Another benefit is that you get away from the > bang-bang behavior you get when having too few bits. > > For an oven you can however cheat some by not requiring linearity in the > "too cold" region of temperature. You do want some linearity as you start > to come into the right range in order to slow down the heating in order not > to do a big overshot. > > I have seen a little too much cases where there been too few bits both on > ADC and DAC sides. Some of it you can overcome, but it runs into trouble. > Get good dynamics, it makes the rest of the design easier. > OK, following the advice both above and below. Let's try some real-world numbers... Lets say my goal is regulation within 0.1C. After filtering I have 10 "good" bits in my ADC. That is 1024 counts. My set point is S. I scale the ADC so that 0 == (S - 0.5) and 1023 == (S + 0.5)This means that each ADC count is 0.001 degree C and within the 0.1C range there are 100 ADC counts. But what if there are only 8 good bits after filtering The each count is 0.004 degree C and there are 25 counts within the 0.1C range. The uP's ADC is nominally 12 bits. Getting 10 "good" noise free bits might be asking to much but 8-bits is pretty reasonable. > > Cheers, > Magnus > > On 06/07/2017 08:32 PM, Bob kb8tq wrote: > >> Hi >> >> There is a gotcha with the initial assumption: You want the loop to be >> *quiet* at a level well below 0.1C. If it is bouncing around that much, >> the second order (rate defendant) tempco of a normal crystal will >> become a pretty major issue. >> >> Simple rule of thumb - add at least two bits past whatever the target is. >> More or less, if you *are* after 0.1C and that comes out to 6 bits, you >> need >> eight solid bits to get things to work properly. >> > -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] uC ADC resolution (was: Poor man's oven)
On Wed, Jun 7, 2017 at 3:18 PM, Bob kb8tq wrote: > Hi > > Consider that a lot of the heat flow is through the glass wall of the > vacuum gizmo. You want to tie your heater(s) to it in order to create > an iso-thermal “wall”. Often this is done by gluing the whole assembly > together. > Not glass walls. Stainless steel. The metal wall make it uniform. I occurred to be that you could fill the container with a liquid. Something that has good thermal conductivity and it would be very uniform inside. I don't know what, transformer oil perhaps? -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] uC ADC resolution (was: Poor man's oven)
One question for the control theory experts.
Assume me goal is to regulate temperer of an aluminum block to within 0.1C,
how good must my ADC be? Is an effective 6-bits good enough?
It seems to me the problem with fewer bits is only quantization noise.
Lets assume 6-bits. This is 1 part in 64. If I scale the input to the
ADC such that it os 1.0C from 0 to 63 counts then each cunt is 1/64 C
which is about 6 times better then my allowed error of 0.6 C.
My gut-feel is that this is marginal but could work ("work" is defined as
holds temperature within the range) but I'd be happier using 8 bits. Im
pretty sure I can get 8-bits by over sampling and filtering.
I don't know how to analyze this but I'm guessing with n-bits each each
sample has a 1/2 bit error so my I and D terms in the PID controller will
accumulate lots of 1/2 bit errors. I thing I want them "a couple orders
of magnitude" smaller then the allied temperature range.
Of cose one could buy the best ADC on the market. But this is POOR MAN's
project. So he asks, "What is the lowers performance/cost part that will
allow the system to meet its specification?
BTW, a related story.I'm on another couple lists that deal with vacuum
tube audio. We see the same things there people correctlypointing out how
to make something better but the question is always how much better and at
what cost an does it matter. So a fun project was proposed. Set a budget
of $200 to build a tube based stereo Hi Fi amplifier. Who can do the
best. Youhade to publish the BOM with prices and suppliers. Extra points
if you came in under budget. This eliminated all the suggestions to buy
high end hand made transformers from Sweden.
IT turrets out that you see MUCH more interesting designs when you lower
the budget. Anyone can make a high performance system even enough money.
They waste half the cost on useless stuff and the product costs double what
it should and is over complex but is works real, really well. That's
easy. Harder and more interesting is "Can you make something just as good
at 1/2 the price?" Answer is usually Yes. Then you say "what much do you
loose if I set the price to 1/4? The answer is surprisingly little if you
get smart about sourcing parts. Turns out about $180 is the minimum
for pretty decent quality HiFi vacuum tube.
An interesting graph would be Oven Specification vs. Price. What is the
minimum cost for keeping temperature to within 1.0 C, for 0.1C, 0.01 C?
Can you do 1.0C for under $5? or 0.1C for under $10.I bet yes.
I did an exercise a while back to see what is the minimum price and
complexity to build a GPSDO that was good enough only to drive the lab
bench instruments I have. I implements only 1/2 od Lars W's design and
cut his lines of code by about 90%. Turns outhe cost is the XO and about
$10. Compared to my Thunderbolt, performance was not nearly as good but
the ratio of performance over parts cost might be better.
On Tue, Jun 6, 2017 at 2:39 PM, Mark Sims wrote:
> Another thing to watch out for on processor ADCs is their performance near
> the supply rails... the AVR ADCs are particularly entertaining below
> around 300 mV (with a 5V Vref).
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Chris Albertson
Redondo Beach, California
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Re: [time-nuts] uC ADC resolution (was: Poor man's oven)
On Tue, Jun 6, 2017 at 2:17 PM, Attila Kinali wrote: > On Tue, 6 Jun 2017 16:37:27 -0400 > Bob kb8tq wrote: > > . Heck, the STM32F4xx have so much internal noise that the ENOB > of their ADC is below 6bit... so low that they even had to write an > appnote on how to do averaging to get back to the 12 bits the ADC is > spec'ed for. (but don't mention that to an ST sales person, they will > hate your guts afterwards). > Can you actually get back all of those bits? How many samples would you need? My current use case for the STM32 ADC is to track battery voltage and maybe 6 bits is enough but if I can get to 12 with a software-only fix I'll take it. Batteries volts charge slowly so I'd have time to take many samples. It's a rather mundane application. Controlling a battery powered motor and I can't let theLiPo battery dichange below a limit so I'm sampling voltage at 1Hz. Got a link to or the name of the app note? > > -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Poor man's oven
> There are more sophisticated control loop designs that can handle this > better, eg by using two temperature sensors, one at the crystal and > one at the heater. But designing them correctly is more difficult > than the normal PID loop. > Keeping with the thread topic, I think this is the key.For the cost of only one more cheap sensor you gain a lot. Harder design as you say but getting help on-line seems to be free. I have gotten PID to work myself with linear systems (motor speed) and I reading up on Kalman Filters as I need them for navigation using multiple sensors. I guess one could use the crystal frequency as a measure of its temperature to tune the system. Is there a name to Google to read up on using two sensors and a pid-like algorithm? -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
