Re: [time-nuts] SDR GPS
On Thu, 24 Nov 2011 10:36:52 -0500 Bob Paddock bob.padd...@gmail.com wrote: Anyone look at the the one from Parallax that Radio Shack is selling for less than $50? http://www.parallax.com/Store/Sensors/CompassGPS/tabid/173/CategoryID/48/List/0/SortField/0/Level/a/ProductID/644/Default.aspx http://www.radioshack.com/product/index.jsp?productId=12302298 It says it is an antenna, do look at the specs closer. These are just standard Sirf based GPS receivers with packaged together with the antenna. Ie these are hardware receivers not SDR. Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] Clocking a PIC16F628A from a Rubidium Standard
On Thu, 24 Nov 2011 09:37:33 -0700 Robert Darlington rdarling...@gmail.com wrote: I've done this but don't remember the detail on the wiring. The data sheet made it clear though. One thing I did notice is that the oscillator seemed to power the chip! If I were doing it again I'd probably use some kind of powered buffer on the oscillator input so that when I power down the circuit it actually stops. This is why i mentioned the DC block capacitor. Even if you use a buffer, you would still power the PIC. The path in this case are the protection diodes on the input pin. By providing there an input voltage, you drive the upper diode which conducts the power to the VDD line which in turn powers the PIC. If you use a buffer, you get still the protection diodes and thus still the path to power the PIC (and the buffer). Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] Clocking a PIC16F628A from a Rubidium Standard
On Thu, 24 Nov 2011 12:05:13 -0700 Kevin Rosenberg ke...@rosenberg.net wrote: Since frequency reference sine wave can exceed Vdd, you want to current limit the external clock. For example, an unterminated TBolt puts out 0-7V Pk-Pk. Atmel, in an app note where they hook up the pins of an AVR to 220V mains, states the over/under voltage protection diodes should not carry more than 1 milliamp of current. But, you should both read the datasheet for the output voltage of the Efratom and measure Pk-Pk voltage output at the point of your PIC. Using the protection diodes as part of the circuit is bad design practice. Use instead explicit shottky diodes (like BAT54S) for clamping. Better would be to use a resisitive divider (probably with a capacitive divider in parallel), a coupling capacitor to connect it to the clock input. You can limit the swing of the signal to less than 1V as the clock input doesnt require a big signal (when using a crystal, the signal can be as low as a few mV, depending on the chip) Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] Clocking a PIC16F628A from a Rubidium Standard
On Nov 25, 2011, at 1:17 AM, Attila Kinali wrote: Using the protection diodes as part of the circuit is bad design practice. In general, I agree completely, Further, I think of operating outside of the datasheet may result in any manner of unspecified behavior. Basically, results while operating outside the datasheet specifications are unspecified. In this case, the use of the protection diode and the 1 ma limit comes directly from the manufacturer Atmel's App Note AVR182 [1]. That said, I'm cautious even when the manufacturer in an App Note says it's okay, but the use falls outside of the datasheet specifications. Thanks for the thoughts on an alternative circuit that doesn't rely on internal device knowledge that may, or may not, be okay. Kevin [1] http://www.atmel.com/dyn/resources/prod_documents/doc2508.pdf ___ 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] Clocking a PIC16F628A from a Rubidium Standard
On Fri, 25 Nov 2011 02:02:04 -0700 Kevin Rosenberg ke...@rosenberg.net wrote: In this case, the use of the protection diode and the 1 ma limit comes directly from the manufacturer Atmel's App Note AVR182 [1]. That said, I'm cautious even when the manufacturer in an App Note says it's okay, but the use falls outside of the datasheet specifications. Don't trust a datasheet blindly. Always apply common sense and a bit of caution. Especially when it comes to Atmel. In the past 2 years, i've discovered 3 silicon bugs in Atmel chips and two bugs in their documentation. Reporting the silicon bugs resulted in being completely ignored and the documentation bugs were answered with (literally) it's a silicon thing, completely disregarding the fact that following the documentation will cause hard to trace bugs in the software (that's how i discovered them in the first place). Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] DGPS@home
Yes, if you use statistics then you must be slow or, better, stop and collect data. I think that ionosphere movements that cause errors are slower than robots movements so it is hard to collect enough data for statistics, of course maybe that only two points to average out is better than nothing... On Fri, Nov 25, 2011 at 7:43 AM, Chris Albertson albertson.ch...@gmail.comwrote: I think the accuracy could be quite good if you took advantage of the times the robot was motionless. During those times it could build up many seconds of averaging and then while moving either use dead reckoning or inertial navigation. On Thu, Nov 24, 2011 at 4:01 AM, ehydra ehy...@arcor.de wrote: Hi all! I wonder what would be reasonable location accuracy if two cheap same type GPS modules will be several meters apart? I understand that it involves statistical numbers. Any idea? Say for a small robot. Thanks! - Henry -- ehydra.dyndns.info ___ 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.
Re: [time-nuts] Clocking a PIC16F628A from a Rubidium Standard
Attila, In the past 2 years, i've discovered 3 silicon bugs in Atmel chips and two bugs in their documentation. Reporting the silicon bugs resulted in being completely ignored and the documentation bugs were answered with (literally) it's a silicon thing, completely disregarding the fact that following the documentation will cause hard to trace bugs in the software (that's how i discovered them in the first place). Can you please contact me offline at df...@ulrich-bangert.de for a discussion on this topic? I use lots of ATTINY85, ATMEGA32 and ATMEGA2560 and have also discovered some issues with ATMEL processors (specially with the 32). Want to learn more about what you found. Best regards Ulrich -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im Auftrag von Attila Kinali Gesendet: Freitag, 25. November 2011 13:14 An: Discussion of precise time and frequency measurement Betreff: Re: [time-nuts] Clocking a PIC16F628A from a Rubidium Standard On Fri, 25 Nov 2011 02:02:04 -0700 Kevin Rosenberg ke...@rosenberg.net wrote: In this case, the use of the protection diode and the 1 ma limit comes directly from the manufacturer Atmel's App Note AVR182 [1]. That said, I'm cautious even when the manufacturer in an App Note says it's okay, but the use falls outside of the datasheet specifications. Don't trust a datasheet blindly. Always apply common sense and a bit of caution. Especially when it comes to Atmel. In the past 2 years, i've discovered 3 silicon bugs in Atmel chips and two bugs in their documentation. Reporting the silicon bugs resulted in being completely ignored and the documentation bugs were answered with (literally) it's a silicon thing, completely disregarding the fact that following the documentation will cause hard to trace bugs in the software (that's how i discovered them in the first place). Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] DGPS@home
On Fri, Nov 25, 2011 at 06:26, ehydra ehy...@arcor.de wrote: I read that for position accuracy ionospheric effects are the main source for typical single frequency receivers. So looking for DOP would be not helpful because the ionospheric way is for two 'relative' on the same position located teceivers vs. satellites position almost the same and that would cancel this error source out!? The end-effect should be better values than seen in the datasheet. Ionospheric effects account for about half the DOP, IIRC. So, if I understand your requirement, and you are interested only in the relative difference of position between two nearby units, you should obtain a relative precision about double of the absolute precision of a single unit. If the units make use of WAAS or EGNOS, probably the gain in relative precision would be less, I think. If you do a test, let us know your findings. Cheers P. ___ 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] SDR GPS
On 11/24/11 9:33 AM, Collins, Graham wrote: Perhaps not in the same league or with the same gee-whiz appeal as a SDR GPS receiver but how about your own DIY GPS receiver: http://dangerousprototypes.com/2011/11/24/homemade-gps-receiver/ and the authors web page: http://www.holmea.demon.co.uk/GPS/Main.htm Yes, indeed.. that's sort of the other approach to building receivers, with a first mixer and filtering at IF. These days, most people just amplify and filter at the L1,L2,L5 frequencies and sample the 1 bit output at an appropriate rate (38-39 MHz). With Holme's approach, you need to synthesize the 1.5 GHz LO, which takes more gates, parts, 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.
Re: [time-nuts] RTC-62421A and GPS
What about a script that sends data to the TRACKBOX (if the BOX is connected to a PC)? Otherwise a PIC (or anything else of your choice with 2 serial ports) that sends the same data collected from the GPS... On Fri, Nov 25, 2011 at 6:31 PM, Joe Leikhim jleik...@leikhim.com wrote: I have a standalone device which uses the EPSON RTC-62421A real time clock. Can anyone suggest a way to synch this RTC to GPS or better yet accept time data from a GPS such as a DATUM ET9390-6000. Is there a drop in replacement for the RTC that will provide an interface? The device is TAPR TRAKBOX for satellite tracking. Presently time is set manually via terminal mode on this device. -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida www.Leikhim.com jleik...@leikhim.com 407-982-0446 Note to GMail Account users. Due to an abnormally high volume of spam originating from bogus GMail accounts, I have found it necessary to block certain GMail traffic. Please phone me if you believe your message was not received. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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] Clocking a PIC16F628A from a Rubidium Standard
On Fri, Nov 25, 2011 at 12:17 AM, Attila Kinali att...@kinali.ch wrote: On Thu, 24 Nov 2011 12:05:13 -0700 Kevin Rosenberg ke...@rosenberg.net wrote: Since frequency reference sine wave can exceed Vdd, you want to current limit the external clock. For example, an unterminated TBolt puts out 0-7V Pk-Pk. Atmel, in an app note where they hook up the pins of an AVR to 220V mains, states the over/under voltage protection diodes should not carry more than 1 milliamp of current. But, you should both read the datasheet for the output voltage of the Efratom and measure Pk-Pk voltage output at the point of your PIC. Using the protection diodes as part of the circuit is bad design practice. Use instead explicit shottky diodes (like BAT54S) for clamping. I agree entirely. I had an AtoD converter that if I let the protection diodes conduct at all, would be several counts out. In this case, even a schottky diode wasn't enough! I ended up clamping to slightly less than Vdd using a schottky diode and a TL431 to provide about Vdd-0.2V. Orin. ___ 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] Vectron 217-9043 10MHz OCXO
While in Florida on business last week, fairly close to Cape Canaveral, I stopped in at the only surplus house I could find: AstroToo in Melbourne. Poking around there, I found several Vectron 217-9043 10MHz OCXO. I could not readily find any info on this model/series at the time of purchase, but bought one anyway. Cheap entertainment no matter what the outcome :) Thing is, I still cant find any directly relevant info. Digging through the time-nuts archives, I found info on other Vectron OCXO that have a similar 7 pin connector on the bottom, but this unit has no SMA connector - only the 7 pins. The standard for these seems to be: 1 - Output 2 - Case 3 - Power -/Case 4 - Power + 5 - EFC Supply (if present) 6 - EFC Input 7 - EFC -/Case That seems to pretty much match this model, and I've noted that at 12V, there is distortion in the output, but at 15 V it looks clean. It's not quite a sine wave, but it looks reasonable as does the output level. The current starts out around 400ma and drops to 70-80ma once warmed up. So I don't think the supply voltage is too far off. The thing is, pin 5 instead of being not connected, ground or some EFC supply voltage, also has 10MHz on it at about twice the output level as pin 1, but seems quite sensitive to load. Pins 6 and 7 are apparently not connected. The pin 5 signal doesnt match any 7 pin Vectron OCXO pinouts that I can find, so I'm not sure what the story is on this unit. I'm currently running it on the bench, letting it settle in. Would have been nice if it had EFC but that doesn't seem to be the case. If anyone has any info on this series OCXO, I would much appreciate seeing it. Thanks! Paul - K9MR ___ 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] Clocking a PIC16F628A from a Rubidium Standard
Hi, Microchip cerainly condone using input protection diodes of PIC devices as clamps. There are application notes for zero-crossing detection which connect the input to the 115V AC line via a resistor. Note that these are intentional protection diodes, not unavoidable parasitic junctions. Typical Absolute max clamp current (inc. 16F628) is +-20mA. As a side note, when using these diodes for ESD protection, Microchip recommend using 0.01uF supply decoupling capacitors close to the chip rather than 0.1uF. This reduces the peak current. Trace inductance limits the effect of more distant capacitive loading. Robert G8RPI. From: Attila Kinali att...@kinali.ch To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, 25 November 2011, 8:17 Subject: Re: [time-nuts] Clocking a PIC16F628A from a Rubidium Standard On Thu, 24 Nov 2011 12:05:13 -0700 Kevin Rosenberg ke...@rosenberg.net wrote: Since frequency reference sine wave can exceed Vdd, you want to current limit the external clock. For example, an unterminated TBolt puts out 0-7V Pk-Pk. Atmel, in an app note where they hook up the pins of an AVR to 220V mains, states the over/under voltage protection diodes should not carry more than 1 milliamp of current. But, you should both read the datasheet for the output voltage of the Efratom and measure Pk-Pk voltage output at the point of your PIC. Using the protection diodes as part of the circuit is bad design practice. Use instead explicit shottky diodes (like BAT54S) for clamping. Better would be to use a resisitive divider (probably with a capacitive divider in parallel), a coupling capacitor to connect it to the clock input. You can limit the swing of the signal to less than 1V as the clock input doesnt require a big signal (when using a crystal, the signal can be as low as a few mV, depending on the chip) Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] PC time app
Just redoing a PC in the shop. Don't know if I've suggested a program called NMEATime to the nuts. I've had this program running on everything from Win2k to Win7, no hitches. It will sync the PC clock to either a GPS or to a network signal, at a chooseable update period. Highly recommended and right now available for $15.00 through Paypal. A bargain IMHO. I have nothing to do with those that bring you the program. Don -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.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] Thunderbolt Monitoring for Pocket PC
Nuts, A while back, I scored an old Compaq iPaq Pocket PC for cheap at an auction. Recently, I wrote a program for it that reads the time and health information from a Thunderbolt and displays it in real-time. More info available here: http://www.fuzzythinking.com/projects/thunderhead/ I may be the only guy in the world who owns both of those pieces of hardware, but in case anyone else does, please enjoy this program. Thanks, -Justin ___ 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] PC time app
Good old nema time. Indeed I started using it on win98 or was it 95?? Way back is the right answer. In fact I have a very old laptop that essentially runs just that program. It also generates time codes. IRIG B as I recall and thats what really made it useful. Good top know they are still around and $15 is cheap. Thanks Paul WB8TSL On Fri, Nov 25, 2011 at 5:01 PM, Don Latham d...@montana.com wrote: Just redoing a PC in the shop. Don't know if I've suggested a program called NMEATime to the nuts. I've had this program running on everything from Win2k to Win7, no hitches. It will sync the PC clock to either a GPS or to a network signal, at a chooseable update period. Highly recommended and right now available for $15.00 through Paypal. A bargain IMHO. I have nothing to do with those that bring you the program. Don -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.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.
Re: [time-nuts] PC time app
I have a copy and I like it, however you can just set your system scheduler to update your clock more often. Win 7 is 1x a week out of the box but it's easy enough to set to once every 15 minutes if you want. It's also free. http://answers.microsoft.com/en-us/windows/forum/windows_7-windows_programs/windows-7-time-sync-runs-update-weekly-how-do-i/3ad0278b-370d-416d-867a-534729ca7d32 -Bob On Fri, Nov 25, 2011 at 3:01 PM, Don Latham d...@montana.com wrote: Just redoing a PC in the shop. Don't know if I've suggested a program called NMEATime to the nuts. I've had this program running on everything from Win2k to Win7, no hitches. It will sync the PC clock to either a GPS or to a network signal, at a chooseable update period. Highly recommended and right now available for $15.00 through Paypal. A bargain IMHO. I have nothing to do with those that bring you the program. Don -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.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.
Re: [time-nuts] PC time app
Yeah. I just found out that my XP and 7 systems can do this update. Red face! Just goes to show ya. Don Robert Darlington I have a copy and I like it, however you can just set your system scheduler to update your clock more often. Win 7 is 1x a week out of the box but it's easy enough to set to once every 15 minutes if you want. It's also free. http://answers.microsoft.com/en-us/windows/forum/windows_7-windows_programs/windows-7-time-sync-runs-update-weekly-how-do-i/3ad0278b-370d-416d-867a-534729ca7d32 -Bob On Fri, Nov 25, 2011 at 3:01 PM, Don Latham d...@montana.com wrote: Just redoing a PC in the shop. Don't know if I've suggested a program called NMEATime to the nuts. I've had this program running on everything from Win2k to Win7, no hitches. It will sync the PC clock to either a GPS or to a network signal, at a chooseable update period. Highly recommended and right now available for $15.00 through Paypal. A bargain IMHO. I have nothing to do with those that bring you the program. Don -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.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. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.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] PC time app
If you have a Thunderbolt, Lady Heather will sync your time for free... It can sync the time via a keyboard command (TS) or via command line options on a regular basis, or whenever the system clock and GPS clock differ by a given amount. You can specify the inherent delay between the Tbolt time messages and actual time (default 45 milliseconds).It's not a fancy pants NTP, but can typically keep your system clock within a few (20?) milliseconds. --- Good top know they are still around and $15 is cheap. ___ 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] Surplus Sources
In the Bay Area, Excess Solutions. Milpitas, Ca. ___ 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] PC time app
Dunno. Does the NMEA driver work on the Meinberg NTP for Windows? Yes, although from some GPS devices the jitter may be worse than from Internet servers (depending on your connection). Given that NTP is free, works extremely well, is well documented, and can be monitored and managed remotely, I don't see why you would want to pay for program which doesn't work as well. I've written some basic notes on installing on Windows here: http://www.satsignal.eu/ntp/setup.html Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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] PC time app
On Fri, Nov 25, 2011 at 9:24 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: Dunno. Does the NMEA driver work on the Meinberg NTP for Windows? Yes, although from some GPS devices the jitter may be worse than from Internet servers (depending on your connection). Given that NTP is free, works extremely well, is well documented, and can be monitored and managed remotely, I don't see why you would want to pay for program which doesn't work as well. That is what every Linux user says about Windows. But it's worse than just not working as well jumping the clock is a defective design. Any software that periodically sets the clock will break a lot of other software that tries to measure time intervals. It is simple: The way to meaue a time interval is to sample the clock, do something, then sample the clock gain. then subtract the first time from the last and then you know how long it took to do that something.Setting the clock periodically breaks this. The only thing that can work is to adjust the clock RATE by tiny amounts Now if you only need enough accuracy so that you are not late to appointments then just do whatever. But we assume on a time nuts list that we care about milli and micro seconds at least 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] PC time app
I'm curious as to what folks are doing with PC's that require micro second accuracy for days or weeks or what have you. Any examples? Curious, Steve On Sat, Nov 26, 2011 at 12:50 AM, Chris Albertson albertson.ch...@gmail.com wrote: On Fri, Nov 25, 2011 at 9:24 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: Dunno. Does the NMEA driver work on the Meinberg NTP for Windows? Yes, although from some GPS devices the jitter may be worse than from Internet servers (depending on your connection). Given that NTP is free, works extremely well, is well documented, and can be monitored and managed remotely, I don't see why you would want to pay for program which doesn't work as well. That is what every Linux user says about Windows. But it's worse than just not working as well jumping the clock is a defective design. Any software that periodically sets the clock will break a lot of other software that tries to measure time intervals. It is simple: The way to meaue a time interval is to sample the clock, do something, then sample the clock gain. then subtract the first time from the last and then you know how long it took to do that something.Setting the clock periodically breaks this. The only thing that can work is to adjust the clock RATE by tiny amounts Now if you only need enough accuracy so that you are not late to appointments then just do whatever. But we assume on a time nuts list that we care about milli and micro seconds at least 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] Low noise power supplies - dont' use Electrolytics
Electrolytic caps have an extremely poor lifetime (MTBF). Sanyo on their website state 50K Hrs at 50C. This means only 6250 MTBF hours at 80C for one single cap. MTBF gets worse the more caps are being used of course. I have seen some Panasonic electrolytics state only 2000 hours MTBF at temperature in their datasheets. That's not even one year before a mean failure occurs making these useless in high-reliability applications. Note also that caps in high AC current situations (Buck DC-DC switcher input cap for example) will self heat due to internal resistance, making things even worse. This is probably one of the main failure reasons for PC motherboards. And that's with name brand parts, it's even worse if one ends up buying counter-fit or non-name-brand Electrolytics. Some of our competitors use Electrolytics all over the place (we don't use any electrolytics) - that's been good for our business. bye, Said In a message dated 11/24/2011 17:08:42 Pacific Standard Time, li...@lazygranch.com writes: I'm not familiar with rubycon caps. The low ESR large value caps are organic semiconductor. OSCON is a common brand from Sanyo. Finding the ultimate cap is nearly as much fun as finding the ultimate LDO. Check out Nichicon. Or you can stick with the Rubycon. Glancing at their website, they seem to copy the Nichicon product line. ___ 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] PC time app
On Fri, Nov 25, 2011 at 9:24 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: Dunno. Does the NMEA driver work on the Meinberg NTP for Windows? Yes, although from some GPS devices the jitter may be worse than from Internet servers (depending on your connection). Given that NTP is free, works extremely well, is well documented, and can be monitored and managed remotely, I don't see why you would want to pay for program which doesn't work as well. That is what every Linux user says about Windows. G - but if Linux doesn't run the software you need to run . But it's worse than just not working as well jumping the clock is a defective design. Any software that periodically sets the clock will break a lot of other software that tries to measure time intervals. It is simple: The way to meaue a time interval is to sample the clock, do something, then sample the clock gain. then subtract the first time from the last and then you know how long it took to do that something.Setting the clock periodically breaks this. The only thing that can work is to adjust the clock RATE by tiny amounts Now if you only need enough accuracy so that you are not late to appointments then just do whatever. But we assume on a time nuts list that we care about milli and micro seconds at least Chris Albertson Redondo Beach, California .. and just to be clear, NTP does its best to use RATE adjustments, and avoid stepping the clock (except when the system is first booted). It's other software which may step rather than rate adjust. Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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] Clocking a PIC16F628A from a Rubidium Standard
As far as the atmel (avr): Almost all my projects use AVR microcontrollers, Due to the RD nature of my work I've /always/ pushed the envelope. I use data sheets as a guideline and nothing else. Years ago I poked around publically at the avr forum about the idea of exploiting undocumented instructions. People in general were not interested in anything out documentation parlance. *Burn in * is second nature to me. Both profiling and application. As far as powering down a MCU while keeping a clock running, The easiest solutions i've found are to use a field effect, i prefer jfet but signal fets would work just as well. This way you don't need to be concerned about back feeding power from IO or in this case the clock/oscillator input. Steve On Fri, Nov 25, 2011 at 4:21 PM, Robert Atkinson robert8...@yahoo.co.ukwrote: Hi, Microchip cerainly condone using input protection diodes of PIC devices as clamps. There are application notes for zero-crossing detection which connect the input to the 115V AC line via a resistor. Note that these are intentional protection diodes, not unavoidable parasitic junctions. Typical Absolute max clamp current (inc. 16F628) is +-20mA. As a side note, when using these diodes for ESD protection, Microchip recommend using 0.01uF supply decoupling capacitors close to the chip rather than 0.1uF. This reduces the peak current. Trace inductance limits the effect of more distant capacitive loading. Robert G8RPI. From: Attila Kinali att...@kinali.ch To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, 25 November 2011, 8:17 Subject: Re: [time-nuts] Clocking a PIC16F628A from a Rubidium Standard On Thu, 24 Nov 2011 12:05:13 -0700 Kevin Rosenberg ke...@rosenberg.net wrote: Since frequency reference sine wave can exceed Vdd, you want to current limit the external clock. For example, an unterminated TBolt puts out 0-7V Pk-Pk. Atmel, in an app note where they hook up the pins of an AVR to 220V mains, states the over/under voltage protection diodes should not carry more than 1 milliamp of current. But, you should both read the datasheet for the output voltage of the Efratom and measure Pk-Pk voltage output at the point of your PIC. Using the protection diodes as part of the circuit is bad design practice. Use instead explicit shottky diodes (like BAT54S) for clamping. Better would be to use a resisitive divider (probably with a capacitive divider in parallel), a coupling capacitor to connect it to the clock input. You can limit the swing of the signal to less than 1V as the clock input doesnt require a big signal (when using a crystal, the signal can be as low as a few mV, depending on the chip) Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] PC time app
I'm curious as to what folks are doing with PC's that require micro second accuracy for days or weeks or what have you. Any examples? Curious, Steve I hear of folks measuring time delay of off-air radio signals, where millisecond accuracy is required. Data from multiple receivers in multiple locations is compared. You need good accuracy for geolocating weather satellite data - one second timing error can result in a 7 km location error, so orbit prediction accuracy comes into that as well. It's a similar requirement when pointing a narrow beamwidth antenna at a distant satellite - note that they had to add a wider beamwidth antenna to one of the ESA dishes trying to talk to the Phobos-Grunt probe recently. Milliseconds suits me, though. Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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] Low noise power supplies - dont' use Electrolytics
Many of us have seen electronic equipment last longer then one year. Some of use even have still working antiques with old eletro caps. Those short lifetimes assume a worse case, usually with a very high ripple current. IOf you can reduce the ripple the MTBF goes up. One question: How does one avoid using electrolytic caps if you need (say) 1,000uF or even 100uF. Those would be some mighty big film caps. On Fri, Nov 25, 2011 at 10:06 PM, saidj...@aol.com wrote: Electrolytic caps have an extremely poor lifetime (MTBF). Sanyo on their website state 50K Hrs at 50C. This means only 6250 MTBF hours at 80C for one single cap. MTBF gets worse the more caps are being used of course. I have seen some Panasonic electrolytics state only 2000 hours MTBF at temperature in their datasheets. That's not even one year before a mean failure occurs making these useless in high-reliability applications. Note also that caps in high AC current situations (Buck DC-DC switcher input cap for example) will self heat due to internal resistance, making things even worse. This is probably one of the main failure reasons for PC motherboards. And that's with name brand parts, it's even worse if one ends up buying counter-fit or non-name-brand Electrolytics. Some of our competitors use Electrolytics all over the place (we don't use any electrolytics) - that's been good for our business. bye, Said In a message dated 11/24/2011 17:08:42 Pacific Standard Time, li...@lazygranch.com writes: I'm not familiar with rubycon caps. The low ESR large value caps are organic semiconductor. OSCON is a common brand from Sanyo. Finding the ultimate cap is nearly as much fun as finding the ultimate LDO. Check out Nichicon. Or you can stick with the Rubycon. Glancing at their website, they seem to copy the Nichicon product line. ___ 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] Low noise power supplies - dont' use Electrolytics
How about this way: Amplifying capacitance.. (Base/Ground cap * Beta) http://sound.westhost.com/project15.htm One question: How does one avoid using electrolytic caps if you need (say) 1,000uF or even 100uF. Those would be some mighty big film caps. ___ 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] Low noise power supplies - dont' use Electrolytics
To second the older electronics: I maintain nearly 100 analytical instruments. The old designs(1970-late 80's) are almost all electrolytic caps and none of the caps have ever failed. When I do find a bad cap it's always in a modern design. A high frequency switcher with under rated caps. When i say under rated i mean take the peak figure and multiple it by two, that's the real part value. My opinion, bad designs. Steve On Sat, Nov 26, 2011 at 1:25 AM, Chris Albertson albertson.ch...@gmail.comwrote: Many of us have seen electronic equipment last longer then one year. Some of use even have still working antiques with old eletro caps. Those short lifetimes assume a worse case, usually with a very high ripple current. IOf you can reduce the ripple the MTBF goes up. One question: How does one avoid using electrolytic caps if you need (say) 1,000uF or even 100uF. Those would be some mighty big film caps. On Fri, Nov 25, 2011 at 10:06 PM, saidj...@aol.com wrote: Electrolytic caps have an extremely poor lifetime (MTBF). Sanyo on their website state 50K Hrs at 50C. This means only 6250 MTBF hours at 80C for one single cap. MTBF gets worse the more caps are being used of course. I have seen some Panasonic electrolytics state only 2000 hours MTBF at temperature in their datasheets. That's not even one year before a mean failure occurs making these useless in high-reliability applications. Note also that caps in high AC current situations (Buck DC-DC switcher input cap for example) will self heat due to internal resistance, making things even worse. This is probably one of the main failure reasons for PC motherboards. And that's with name brand parts, it's even worse if one ends up buying counter-fit or non-name-brand Electrolytics. Some of our competitors use Electrolytics all over the place (we don't use any electrolytics) - that's been good for our business. bye, Said In a message dated 11/24/2011 17:08:42 Pacific Standard Time, li...@lazygranch.com writes: I'm not familiar with rubycon caps. The low ESR large value caps are organic semiconductor. OSCON is a common brand from Sanyo. Finding the ultimate cap is nearly as much fun as finding the ultimate LDO. Check out Nichicon. Or you can stick with the Rubycon. Glancing at their website, they seem to copy the Nichicon product line. ___ 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.
Re: [time-nuts] PC time app
david-tay...@blueyonder.co.uk said: Yes, although from some GPS devices the jitter may be worse than from Internet servers (depending on your connection). I've been looking for good, low cost GPS gizmos, preferably with no soldering required. If anybody finds one, please let me/us know. The best I've found is the Garmin GPS-18x. It is only good if you can use the PPS signal and it requires some soldering. All the low cost GPS unit's I've tested have horrible jitter. They are crappy without PPS support. In particular, the USB units don't have anything like PPS. I'd call them good-enough if they worked as well as I hope. The USB jitter is not a problem, at least for some/many people. It's small relative to network delays. I'd consider a USB device good enough to be interesting if it worked as expected. The problem isn't just jitter, it's wander. By that I mean very low frequency that's hard to filter out. Ballpark number is 25 ms of jitter and 100 ms of wander. These are from SiRF chips on USB: http://www.megapathdsl.net/~hmurray/bb/gps/Holux-2.png http://www.megapathdsl.net/~hmurray/bb/gps/BU-353-gpgga.png The older Garmin GPS-18 (non x) was good enough. (but, unfortunately, not as sensitive and no longer available) http://www.megapathdsl.net/~hmurray/ntp/GPS18USB-off.gif On the network I have a 384K DSL line. It's mostly idle. ntpd has no trouble filtering out the occasional poor samples when it happens to collect data while I'm loading a big web page. On the other hand, I occasionally download CDs or such. That takes hours. That ties up the line for long enough so that the queuing delays can confuse ntpd. I've seen delays of 3.5 seconds. There is a bufferbloat project working on that area, but it's going to be a lot of work. http://www.bufferbloat.net/ It's screwing things like VoIP. If/when it gets fixed (or even improved) timkeeping will get better for free. -- These are my opinions, not necessarily my employer's. 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.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
At sane temperatures, OSCONs are very good. Who runs their gear hot enough to boil water? http://edc.sanyo.com/pdf/e_oscon.pdf ___ 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] PC time app
I'm curious as to what folks are doing with PC's that require micro second accuracy for days or weeks or what have you. Any examples? The obvious one is you can be a real time nut. :) With a good clock, you can measure network delays. The normal way that ntp works is to exchange packets with a server. That gives you 4 time stamps: the time the request left the client the time the request arrived the server the time the response left the server the time the response arrived the client ntp assumes the network delays in each direction are the same and adjusts the local clock to get that answer. (that's after lots of filtering and such) If instead, you assume that both clocks are good, you can directly calculate the transit time in each direction. If you are going 1000 miles, 1 ms accuracy is probably good enough. If you are interested in LAN distances you probably need better than that. -- These are my opinions, not necessarily my employer's. 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.
Re: [time-nuts] PC time app
From: Hal Murray Sent: Saturday, November 26, 2011 6:58 AM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] PC time app david-taylor said: Yes, although from some GPS devices the jitter may be worse than from Internet servers (depending on your connection). I've been looking for good, low cost GPS gizmos, preferably with no soldering required. If anybody finds one, please let me/us know. The best I've found is the Garmin GPS-18x. It is only good if you can use the PPS signal and it requires some soldering. All the low cost GPS unit's I've tested have horrible jitter. They are crappy without PPS support. [] I do agree with Hal's comments. The one other unit I've found is this one, which I know I've mentioned here before: http://www.satsignal.eu/ntp/Sure-GPS.htm but again some assembly is required, including soldering. It can take its power from a spare USB port. I did test the GPS 18(x) with a USB to serial adapter, and the PPS/DCD line was passed through, allowing NTP to work rather better than pure LAN sync, but not as good as a direct connection to the serial port DCD line. Not all USB/serial adapters and their drivers work as well. Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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.
