Re: [time-nuts] GPS jump
To me it doesn't look like a real jump but rather a result of aggregated systematics. I think it is related to satellite orbits and how they provide number of birds or lack of good symmetry, or both. Both september 28th and 29th have equivalently large jumps as october 9th. Cheers, Magnus On 10/11/2014 02:24 PM, Jim Palfreyman wrote: http://users.on.net/~cdadsl/ Is a web page with all our different sites on it. Hobart 26m seems to be the only exception but I did make an adjustment on that day. But the adjustment didn't appear. All sites are collected and analysed separately with their own GPS clock. Some are old TACs and most are CNS mark II. It could be a fluke, but it does seem weird. And as was pointed out - this happened last year at around the same time. Well spotted Mike Cook! On 11 October 2014 09:54, Tom Van Baak t...@leapsecond.com wrote: Hi Jim, Can you tell me more about your configuration? What GPS receiver / antenna system do you use; L1 or L1/L2? Is this live 1PPS data, or post-processed from RINEX, etc. Is the data analysis done separately in 5 locations or is the raw data collected and processed together. Through IGS and NASA and BIPM there's GPS and maser data from all over the world so it should be possible to track this down. I can ask people I know too. But can you clarify how much the downward turn is? Is that ps/day, or ns/day, or what. Thanks, /tvb - Original Message - From: Jim Palfreyman jim77...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, October 09, 2014 4:43 PM Subject: [time-nuts] GPS jump Folks, We look after 5 separate hydrogen masers spread all over Australia and we collect tic phases between the masers and the GPS. On around ~Oct 7 we have noticed that the normal steady straight line (with standard daily noise) took a noticeable downward turn - on all 5 masers. Did anyone else who tracks H-masers notice this as well? Is it JPL making corrections? Jim Palfreyman ___ 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] F*watch
On Sun, Oct 12, 2014 at 12:28 AM, Chris Albertson albertson.ch...@gmail.com wrote: On Sat, Oct 11, 2014 at 1:50 PM, Javier Serrano javier.serrano.par...@gmail.com wrote: It's as free-as-in-freedom as we could make it: schematics, layout, case and code, all using free tools. That is really the best part. But I wonder what it would cost to build a copy using your design files. Or what would it cost to build a run of say one dozen?Apple prices their watch at $350 which at first seemed really high but then I started thinking if that was a high price or not I haven't done the math myself, since our objective was never to save money, but I am pretty sure you can convince yourself by looking at the parts list and contacting your favourite distributors (and excluding your own time to learn about it and make it) that the f*watch can be made cheaper than Apple's watch. Having said that, I think you would be comparing apples and oranges ;) Our main objectives with this development were others, in order of decreasing priority: - to give our colleague a gift and a departure party he would remember forever. I think we succeeded on this one! :) - to give him something which would keep him coming back to us to do what he likes best (aside from hiking): hack low-level software. - to explore the limits of what a bunch of hackers can do meeting irregularly on Friday evenings and working intermittently at night and on weekends for a few months, using only free tools. - to start eating our own dog food. We have been contributing to KiCad for some time now [1], and we wanted to evaluate how far we still are from being able to use it at work without a big productivity penalty. So I don't look at the f*watch as a way to save money (and even less, time!) but as a great platform to experiment and have fun. Cheers, Javier [1] http://www.ohwr.org/projects/cern-kicad/wiki ___ 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] FE-5680 Linux command line tool
I use that chip in an old project with an 8051 microcontroller. They are becoming obsolete, I had to switch to the PSD913F if I recall correctly (or maybe the other way around?) I have a couple of the programmers too. They work from the printer port, you are talking about certifiable dinosaurs :) Didier KO4BB On October 11, 2014 3:19:52 PM CDT, Tom Wimmenhove tom.wimmenh...@gmail.com wrote: It's a chip (PSD813F) which has 1MBit flash, 16Kbit SRAM and 256Kbit EEPROM. It's old school with parallel data/address bus and all that :) It does have JTAG. Regards, Tom On Sat, Oct 11, 2014 at 7:45 AM, Didier Juges shali...@gmail.com wrote: Most EEPROMs have I2C or SPI interfaces. Some Flash chips have JTAG. Didier KO4BB On October 10, 2014 4:47:19 PM CDT, Tom Wimmenhove tom.wimmenh...@gmail.com wrote: Thanks Joe! I don't have the clip-ons but of course I could get them. I know the chip has a JTAG interface, but I've only used JTAG with chips that came with a programmer and software :) (except with OpenOCD over parport once, but that was in the stone age). Another question about the EEPROM dump Elio Corbolante. The chip has a 256Kbit (32KB) EEPROM and the dump is 160K: -rw-rw-r-- 1 tom tom 160K nov 8 2012 FE5680A_EEPROM.bin Which part in this dump is the actual data from the EEPROM? Thanks in advance. Regards, Tom On Fri, Oct 10, 2014 at 12:21 PM, Joseph Gray jg...@zianet.com wrote: I don't know how crowded the board is, but I would use an SMD DIP clip instead of unsoldering the chip. Joe Gray W5JG On Oct 10, 2014 8:30 AM, Tom Wimmenhove tom.wimmenh...@gmail.com wrote: I recently came across a thread on this list about undocumented FE5680 commands. I have been using a little linux command line tool I wrote years ago for tuning the unit and decided to add these commands to it. Since this mailing list was the place I found the unit (someone linked to an ebay seller) I figured I' d join the list and throw it on here :) http://www.tomwimmenhove.com/otherstuff/fe5680-0.2.tgz Now, the bad news. I had my unit running overnight while logging the serial command output that reads the ADC, and in the morning it was no longer locked. The 10MHz signal disappears about 5 seconds after power-on, and programmed offset was somehow reset to zero (it had been set to -645). So it appears as if the internal EEPROM has been corrupted. I read a post from Elio Corbolante where he posted EEPROM and firmware dumps. Anyone have any idea on how to re-write this firmware back into the EEPROM by hand (would this be possible through JTAG, or do I actually have to solder the chip out of there? :) ) Or maybe there's someone willing to sell their broken unit I could take the chip out of? Regards, Tom ___ 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. -- Sent from my Motorola Droid Razr HD 4G LTE wireless tracker while I do other things. ___ 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. -- Sent from my Motorola Droid Razr HD 4G LTE wireless tracker while I do other things. ___ 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] Advice on sighting a roof mounted gps area please
Hi All, I am building a house extension and part of the works involves adding a new hip roof made of corrugated iron. I was thinking I would pass a 50mm pvc pipe through the roof with a tee and then mount two conical gps timing antennas on top of it. I am in a low point and don't have visibility of the horizons ( I'm not in the out-back). My question is should I mount on the peak of the roof? How close can I mount two antennas from each other? Can they interfere with each other? I am also in the midst of some tall trees - although my new roof will be pretty high it will still be below the tallest trees. Of course the main reason for this is I want to do some accurate timing ASCII art of proposed set-up A A | | | | ^ / \ /\ / roof \ Thanks for your advice Tim ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Bruce, Thanks, I recall the thread from reading the digests. The CERN code is wonderfully compact but not immediately obvious to a novice to VHDL. Perhaps one day the light will come on. Bob On 10/12/2014 12:27 AM, Bruce Griffiths wrote: Original thread on DDMTD in 2008: https://www.febo.com/pipermail/time-nuts/2008-December/034955.html Later comment on using a shift register to minimise metastability issues: https://www.febo.com/pipermail/time-nuts/2011-August/058648.html Bruce On Sunday, October 12, 2014 12:14:27 AM Robert Darby wrote: Bob Camp, Bob, Simon is talking about the sampler versus a true mixer. This is the idea I asked you about some months ago when I asked about how the digital filter functions. You were kind to explain the filter method in terms of buckets. You are of course correct that the resolution is low, 100 ns for a 10 MHz DUT with a 10 Hz frequency offset but the hetrodyne factor takes the theoretical resolution to 100 fs. That's not shabby for a very low cost DDMTD. And of course, the actual noise floor will not be close to this but potentially it's better than a 5370 and a lot easier to maintain. :o) Simon, I have a 4 channel 1 ns tagger working but I can't successfully link the FTDI library to a c program so doing this in hardware looks far more attractive to me. Here's how I see it at this point: -- Objective: --A four channel DDMTD with 44 bit time tags delivered over the USB port --At least 100 Hz beat frquency on each channel --The hardware is capable of much higher rates but increasing the beat frequency offset --degrades resolution and realistically the device will probably be used at 5 or 10 Hz -- -- Additional Hardware Required: --A wing with three or five LTC6957-1 low phase noise buffers to convert sine inputs into --high speed low-jitter square waves using LVPECL differential outputs --Either an oscillator offset by the beat frequency or a DDS frequency generator --A USB equipped computer -- --Architecture --Differential inputs are fed to the master clock, thence to the D flip-flops clocks --Differential inputs for each channel are fed to the data inputs for each flip-flop --The master clock drives a 44 bit counter which is common to all four channels --Each channel has two independent counters, provisionally 14 bit, designated high and low --The low counter first establishes a low state without transitions i.e. it times out --After the low counter times out, the flip-flop is armed --The first high output at q resets and starts both high and low counters - whichever counts depends on whether q is high or low --Every time the high and low counters match we store the 44 bit count; each new match replaces the previous one --At some point (2^14 highs) the high counter will roll over - hopefully low will have stopped counting much earlier --The highest stored match should meet the equal count criteria as described in the P. Moreira and I. Darwazeh paper --Since there are four channels it will be necessary to multiplex the time tags into the fifo --The multiplexer will add 1 bit per channel for one-hot channel id coding --The 48 bits will clock into a 48 bit to 8 bit fifo thence to an 8 bit USB port I believe you can have multiple points where the two counts match but I don't have any data to confirm that. I played with this in excel and when you feed it ones and zeros in a distribution that looks like the typical output out of a digital sampler it is possible to get multiple matches. My intention is to go with the last crossing and the scheme mentioned above does this rather trivially. Unless, of course, I'm missing something and I usually do. I've got a Pipistrello board and it has the option of an asynchronous fifo USB interface; since I've already paid my dues on that I'll just use that code again. The data rate is so low that snail mail would work. The computer gets a series of time tags and your program has to pair up the channels to get the deltas. Getting time tags lets you compare three or four devices simultaneously and facilitates three-cornered hat calculations. I suspect that's a lot easier to say than do but we'll cross that bridge if we ever get there. Also time tags permit continuous sampling; there's no counter dead-time which I think can be an issue when it causes variable data sampling rates. Bob Camp mention Collins low jitter hard limiters but I suspect that's much more of an issue on the very shallow slopes you see on 5 or 10 Hz mixer outputs. The LTC6957 is probably overkill on 10 MHz inputs but I believe they're a tad better than a 74AC gate, but then again maybe not all that much better. Lot more expensive. Bob C discussed sine to square conversion in a recent post (IIRC) perhaps in connection with 5V to 3.3V conversion, and for a low cost
Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop
Hi With *all* of these “drop to a lower frequency” approaches, the theoretical resolution is very good compared to the useful resolution. A straight mix to 1 Hz into a 5370 is a great example. The filter / limiter is the thing that sets the useful resolution rather than the theoretical 1x10^-17 the setup provides. Bob On Oct 12, 2014, at 12:14 AM, Robert Darby bobda...@triad.rr.com wrote: Bob Camp, Bob, Simon is talking about the sampler versus a true mixer. This is the idea I asked you about some months ago when I asked about how the digital filter functions. You were kind to explain the filter method in terms of buckets. You are of course correct that the resolution is low, 100 ns for a 10 MHz DUT with a 10 Hz frequency offset but the hetrodyne factor takes the theoretical resolution to 100 fs. That's not shabby for a very low cost DDMTD. And of course, the actual noise floor will not be close to this but potentially it's better than a 5370 and a lot easier to maintain. :o) Simon, I have a 4 channel 1 ns tagger working but I can't successfully link the FTDI library to a c program so doing this in hardware looks far more attractive to me. Here's how I see it at this point: -- Objective: --A four channel DDMTD with 44 bit time tags delivered over the USB port --At least 100 Hz beat frquency on each channel --The hardware is capable of much higher rates but increasing the beat frequency offset --degrades resolution and realistically the device will probably be used at 5 or 10 Hz -- -- Additional Hardware Required: --A wing with three or five LTC6957-1 low phase noise buffers to convert sine inputs into --high speed low-jitter square waves using LVPECL differential outputs --Either an oscillator offset by the beat frequency or a DDS frequency generator --A USB equipped computer -- --Architecture --Differential inputs are fed to the master clock, thence to the D flip-flops clocks --Differential inputs for each channel are fed to the data inputs for each flip-flop --The master clock drives a 44 bit counter which is common to all four channels --Each channel has two independent counters, provisionally 14 bit, designated high and low --The low counter first establishes a low state without transitions i.e. it times out --After the low counter times out, the flip-flop is armed --The first high output at q resets and starts both high and low counters - whichever counts depends on whether q is high or low --Every time the high and low counters match we store the 44 bit count; each new match replaces the previous one --At some point (2^14 highs) the high counter will roll over - hopefully low will have stopped counting much earlier --The highest stored match should meet the equal count criteria as described in the P. Moreira and I. Darwazeh paper --Since there are four channels it will be necessary to multiplex the time tags into the fifo --The multiplexer will add 1 bit per channel for one-hot channel id coding --The 48 bits will clock into a 48 bit to 8 bit fifo thence to an 8 bit USB port I believe you can have multiple points where the two counts match but I don't have any data to confirm that. I played with this in excel and when you feed it ones and zeros in a distribution that looks like the typical output out of a digital sampler it is possible to get multiple matches. My intention is to go with the last crossing and the scheme mentioned above does this rather trivially. Unless, of course, I'm missing something and I usually do. I've got a Pipistrello board and it has the option of an asynchronous fifo USB interface; since I've already paid my dues on that I'll just use that code again. The data rate is so low that snail mail would work. The computer gets a series of time tags and your program has to pair up the channels to get the deltas. Getting time tags lets you compare three or four devices simultaneously and facilitates three-cornered hat calculations. I suspect that's a lot easier to say than do but we'll cross that bridge if we ever get there. Also time tags permit continuous sampling; there's no counter dead-time which I think can be an issue when it causes variable data sampling rates. Bob Camp mention Collins low jitter hard limiters but I suspect that's much more of an issue on the very shallow slopes you see on 5 or 10 Hz mixer outputs. The LTC6957 is probably overkill on 10 MHz inputs but I believe they're a tad better than a 74AC gate, but then again maybe not all that much better. Lot more expensive. Bob C discussed sine to square conversion in a recent post (IIRC) perhaps in connection with 5V to 3.3V conversion, and for a low cost solution the 74AC gate
Re: [time-nuts] Advice on sighting a roof mounted gps area please
Tim The antennas should not interfere with each other due to rf leakage because of the way the systems are designed. I will believe you are using 2 rf feeds. The more you can clear the trees the better. My very simple solution is a 90' tower. A bit of humor it does have other uses. Regards Paul WB8TSL On Sun, Oct 12, 2014 at 7:34 AM, swingbyte swingb...@exemail.com.au wrote: Hi All, I am building a house extension and part of the works involves adding a new hip roof made of corrugated iron. I was thinking I would pass a 50mm pvc pipe through the roof with a tee and then mount two conical gps timing antennas on top of it. I am in a low point and don't have visibility of the horizons ( I'm not in the out-back). My question is should I mount on the peak of the roof? How close can I mount two antennas from each other? Can they interfere with each other? I am also in the midst of some tall trees - although my new roof will be pretty high it will still be below the tallest trees. Of course the main reason for this is I want to do some accurate timing ASCII art of proposed set-up A A | | | | ^ / \ /\ / roof \ Thanks for your advice Tim ___ 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] Advice on sighting a roof mounted gps area please
First off, why only 50mm and why plastic? The PVC will degrade in the sunlight over the years. Use galvanized iron pipe. Make the mast as tall as you can. It can extend sever feet below the roof and attach to house structure using u-bolts. (Hight limited only by appearance from the street.) Using iron pipe strength will not be an issue. Run the cable inside the iron pipe to the attic space. I would use two masts, one for each antenna. It will look better and be easier to build and it will handle high winds better. If you are worried about how this all looks use some spray paint to make it either sky blue or light grey. Do you need two antenna? You can feed multiple GPS receivers using a splitter and amplifier from one antenna. Be sure to follow the local rules for grounding antenna. In most places you will need a heavy coper wire leading directly to a grounding rod. You want to give lightening an easy path to ground that is not routed through the interior of the house. On Sun, Oct 12, 2014 at 4:34 AM, swingbyte swingb...@exemail.com.au wrote: Hi All, I am building a house extension and part of the works involves adding a new hip roof made of corrugated iron. I was thinking I would pass a 50mm pvc pipe through the roof with a tee and then mount two conical gps timing antennas on top of it. I am in a low point and don't have visibility of the horizons ( I'm not in the out-back). My question is should I mount on the peak of the roof? How close can I mount two antennas from each other? Can they interfere with each other? I am also in the midst of some tall trees - although my new roof will be pretty high it will still be below the tallest trees. Of course the main reason for this is I want to do some accurate timing ASCII art of proposed set-up A A | | | | ^ / \ /\ / roof \ Thanks for your advice Tim ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Interesting 2008 discussion on using a sound-card ADC for a DMTD system! Did anyone build a DMTD-system and measure the performance using a 24-bit soundcard? Does it matter that the ADC in the sound-card is probably clocked by a crystal clock that is 50ppm off and has bad ADEV? Anders On Sun, Oct 12, 2014 at 7:27 AM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: Original thread on DDMTD in 2008: https://www.febo.com/pipermail/time-nuts/2008-December/034955.html Later comment on using a shift register to minimise metastability issues: https://www.febo.com/pipermail/time-nuts/2011-August/058648.html Bruce ___ 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] TM500/TM5000/HP-5370 Extender cables and cards
Hi Mark - do you recommend one 5370 Extender set or two? I definitely want one. Regards, John -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims Sent: Saturday, October 11, 2014 11:46 PM To: time-nuts@febo.com; volt-n...@febo.com Subject: [time-nuts] TM500/TM5000/HP-5370 Extender cables and cards The TM500/5000 and HP5370 extender kits are now available (actually they were ready a few weeks ago, but I was going to be out of town and did not want to leave people hanging).Prices are:HP5370 extender card kit - has 2 x 36 pin extenders and 1 x 44 pin extender. $30 setTektronix TM500/TM5000 module extender cable kit - $20Tektronix TM5000 GPIB extender cable (assembled) $20US shipping is $6 for any number of kits. International shipping is $15 for any number of kits. If you need international tracking they must go registered mail which adds another $15 (and slows down the mail) or express mail which is stupid expensive. All kits include everything you need to get going except solder and basic tools.Email me for my Paypal address.The HP5370 extenders are 5 inches long.The TM500 kits include a pair of 17 40 pin IDE ribbon cables. You may want to use your own, longer cables. The TM5000 GPIB cable is around 28 long.Remember that some TM500/5000 modules require 2 or 3 extender cables... I even have one that needs 4, but it is a one-off custom design. ___ 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] F*watch
If you want to add wi-fi to a project, take a look at the ESP8266 wifi system-on-a chip. It has a wifi transceiver and a 32 bit processor on a single chip. People have been getting 300 meter range with a PCB antenna. There is now a GCC compiler for it... lots of work going on here: esp8266.com It loads the firmware from a serial EEPROM. There are small PCBs available for around $5 on Ebay. Standard firmware implements serial to wi-fi. ___ 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] Advice on sighting a roof mounted gps area please
Hi If you are going to get any benefit from multiple antennas, you want to space them as far apart as possible. You are better off with one antenna and a splitter than with two close spaced antennas. The cost of mucking around on the roof is non-trivial. The world is headed to L1/L2 operation on GPS and similar systems. Invest the money in one good antenna and mount rather than multiples. Bob On Oct 12, 2014, at 10:19 AM, paul swed paulsw...@gmail.com wrote: Tim The antennas should not interfere with each other due to rf leakage because of the way the systems are designed. I will believe you are using 2 rf feeds. The more you can clear the trees the better. My very simple solution is a 90' tower. A bit of humor it does have other uses. Regards Paul WB8TSL On Sun, Oct 12, 2014 at 7:34 AM, swingbyte swingb...@exemail.com.au wrote: Hi All, I am building a house extension and part of the works involves adding a new hip roof made of corrugated iron. I was thinking I would pass a 50mm pvc pipe through the roof with a tee and then mount two conical gps timing antennas on top of it. I am in a low point and don't have visibility of the horizons ( I'm not in the out-back). My question is should I mount on the peak of the roof? How close can I mount two antennas from each other? Can they interfere with each other? I am also in the midst of some tall trees - although my new roof will be pretty high it will still be below the tallest trees. Of course the main reason for this is I want to do some accurate timing ASCII art of proposed set-up A A | | | | ^ / \ /\ / roof \ Thanks for your advice Tim ___ 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] TM500/TM5000/HP-5370 Extender cables and cards
We certainly allow, maybe even encourage, occasional sales of time frequency related stuff on the list. But please send inquiries, orders, and replies directly to the OP, rather than the entire list. In this case your emails should go to: Mark Sims hol...@hotmail.com Thanks, /tvb Hi Mark - do you recommend one 5370 Extender set or two? I definitely want one. Regards, John ___ 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] TM500/TM5000/HP-5370 Extender cables and cards
I suspect that 90% of the work could be done with a single kit. That will get one card out of the chassis. But, there are always those annoying problems where getting two cards out can make life a little easier. With two kits you could also hack up the extra 44-pin board to make a smaller board (or boards) for getting the odd-ball cards out (if you can find the required edge connectors). So far, I've only needed to do a single card... I suspect most TM500 people will want two cables, but that depends upon what modules you have. Most modules just have one connector. Some of the fancier ones use two. And a very few use three. I even have a custom module that has 4... At first, I didn't think that the TM5000 GPIB extender cable would be all that important, but I have wound up using it several times. -- Hi Mark - do you recommend one 5370 Extender set or two? ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
anders.e.e.wal...@gmail.com said: Does it matter that the ADC in the sound-card is probably clocked by a crystal clock that is 50ppm off and has bad ADEV? You can calibrate the clock on the ADC. One way is to feed a known reference frequency in on the other channel. (That's assuming you have a stereo setup and don't need the second channel for something else.) Another way is to compare the sample rate with the PC clock. That will correct for any long term drift but may not track shorter transients. -- 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.
Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop
Hi If you are mixing down to 10 Hz, and are looking for 1x10^-7 on the 10 Hz, that equates to a stability / accuracy spec of 0.1 ppm on the ADC clock. A 20 to 100 ppm offset on the clock is not all that unusual. Calibrating out initial offset to 1 ppm is pretty simple. If you can poke a counter onto the clock output, you can get a lot closer than that. The clock probably drifts in the 0.1 to 1.0 ppm / C range. If your room cycles 2 C every hour, correcting that to 0.1 ppm is quite do-able via a “spare” channel. You can record on an input or monitor a signal generated on an output. If your room is stable enough / your stability is good enough you may get away without doing real time correction. Unless your clock has really bad specs, it’s ADEV should be below 1x10^-9 at 0.1 to 10 seconds. That’s 100X better than what you are after. If the clock is a lot worse than these numbers, the audio properties of the ADC will begin to degrade. That more than anything else is what makes this all work. Bob On Oct 12, 2014, at 2:37 PM, Hal Murray hmur...@megapathdsl.net wrote: anders.e.e.wal...@gmail.com said: Does it matter that the ADC in the sound-card is probably clocked by a crystal clock that is 50ppm off and has bad ADEV? You can calibrate the clock on the ADC. One way is to feed a known reference frequency in on the other channel. (That's assuming you have a stereo setup and don't need the second channel for something else.) Another way is to compare the sample rate with the PC clock. That will correct for any long term drift but may not track shorter transients. -- 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] Digital Mixing with a BeagleBone Black and D Flip Flop
HI A little more information: If you are doing the ADC thing, you still need to estimate zero crossings. In all likelihood you would be doing bandpass filtering first (say 8 Hz to 12 Hz) on your 10 Hz note. Next you would do some sort of estimator to get the zero cross. A curve fit is one sort of estimator, there are others. A simple straight line fit over 4 or so points might do it. A higher order fit over a few more points is possible. Why does that matter? The fit improves your accuracy quite a bit. It also reduces your vulnerability to odd single sample issues like popcorn noise. Since you are running at a very low frequency 1/f noise can be an issue. Bob On Oct 12, 2014, at 2:37 PM, Hal Murray hmur...@megapathdsl.net wrote: anders.e.e.wal...@gmail.com said: Does it matter that the ADC in the sound-card is probably clocked by a crystal clock that is 50ppm off and has bad ADEV? You can calibrate the clock on the ADC. One way is to feed a known reference frequency in on the other channel. (That's assuming you have a stereo setup and don't need the second channel for something else.) Another way is to compare the sample rate with the PC clock. That will correct for any long term drift but may not track shorter transients. -- 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] Advice on sighting a roof mounted gps area please
kb...@n1k.org said: If you are going to get any benefit from multiple antennas, you want to space them as far apart as possible. You are better off with one antenna and a splitter than with two close spaced antennas. Does anybody have data? How would I measure it? Where is the knee? I assume the distance is measured in wavelengths. Is it 1, 10, ...? In a related area, does anybody have data that correlates with rain? (or fog/mist) -- 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.
Re: [time-nuts] Advice on sighting a roof mounted gps area please
HI Many years ago, we got dinged on customer visit when they spotted our GPS antenna array on the roof. The claim made at the time was that anything under 20’ spacing was counterproductive. I’ve seen numbers like 5, 8, 10,15 and 25 feet mentioned by different people at different times. The problems seem to be: 1) You have an amp in the antenna, like it or not, the antenna (and it’s coax) are not 100% shielded. They re-radiate. 2) The antenna structure (mast etc) is a reflector and you get multi-path. 3) The GPS solution does not vary enough over a short distance for a “second opinion” to be useful 4) Gear on the other end of the antenna could re-radiate. (number 4 on the list for an obvious reason … = I don’t believe it) The first one on the list is what they dinged us on. Since it was their antenna, we sort of figured they knew something about what it did or did not do. The other three get mentioned here and there. Bob On Oct 12, 2014, at 5:07 PM, Hal Murray hmur...@megapathdsl.net wrote: kb...@n1k.org said: If you are going to get any benefit from multiple antennas, you want to space them as far apart as possible. You are better off with one antenna and a splitter than with two close spaced antennas. Does anybody have data? How would I measure it? Where is the knee? I assume the distance is measured in wavelengths. Is it 1, 10, ...? In a related area, does anybody have data that correlates with rain? (or fog/mist) -- 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Robert, Bob Camp mention Collins low jitter hard limiters but I suspect that's much more of an issue on the very shallow slopes you see on 5 or 10 Hz mixer outputs. The LTC6957 is probably overkill on 10 MHz inputs but I believe they're a tad better than a 74AC gate, but then again maybe not all that much better. Lot more expensive. Bob C discussed sine to square conversion in a recent post (IIRC) perhaps in connection with 5V to 3.3V conversion, and for a low cost solution the 74AC gate looks pretty good and they're easy to dead bug. Sine-to-square conversion and Collins low jitter hard limiters is related to slew-rate limited resolution. If you have 1E-12 resolution, and see about 20 steps, then over a period of 20 ps the sampler is unable to make a stable sampling. For a 74AC that is not very surprising. You might benefit from some slew-rate improvement on the input. Maybe look at the TADD-2 input for inspiration. The slew-rate adaptation aims to reduce the slew-rate as being the major impact on noise, but the inputs inherent noise then needs to be handled. This is both the samplers/DFF jitter and the other signals jitter. Cheers, Magnus ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Hi, Some attempts have been made. Never got around to write the needed code. On 10/12/2014 08:37 PM, Hal Murray wrote: anders.e.e.wal...@gmail.com said: Does it matter that the ADC in the sound-card is probably clocked by a crystal clock that is 50ppm off and has bad ADEV? You can calibrate the clock on the ADC. One way is to feed a known reference frequency in on the other channel. (That's assuming you have a stereo setup and don't need the second channel for something else.) Another way is to compare the sample rate with the PC clock. That will correct for any long term drift but may not track shorter transients. Many more professional audio interfaces allows you to supply a word-clock, so synthesizing that from suitable source would provide good means of adjustment. 48 kHz or multiples is often used. Cheers, Magnus ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Increasing the beat frequency to find a balance between 1/f noise and f/delta-f amplification may be worth doing and have been seen done to find optimum performance. If you use hard limiters or audio channels to achieve it is however a little detail. The benefit of audio channels is that the A/B channels does not disperse out in time, such that you loose cross-correlation of transfer oscillator noise. Some AD inputs may need to be modified to remove DC-blocking cap. Not all ADCs is happy with this. Some boards already have that and do DC-removal in digital filters. Cheers, Magnus On 10/12/2014 11:09 PM, Bob Camp wrote: HI A little more information: If you are doing the ADC thing, you still need to estimate zero crossings. In all likelihood you would be doing bandpass filtering first (say 8 Hz to 12 Hz) on your 10 Hz note. Next you would do some sort of estimator to get the zero cross. A curve fit is one sort of estimator, there are others. A simple straight line fit over 4 or so points might do it. A higher order fit over a few more points is possible. Why does that matter? The fit improves your accuracy quite a bit. It also reduces your vulnerability to odd single sample issues like popcorn noise. Since you are running at a very low frequency 1/f noise can be an issue. Bob On Oct 12, 2014, at 2:37 PM, Hal Murray hmur...@megapathdsl.net wrote: anders.e.e.wal...@gmail.com said: Does it matter that the ADC in the sound-card is probably clocked by a crystal clock that is 50ppm off and has bad ADEV? You can calibrate the clock on the ADC. One way is to feed a known reference frequency in on the other channel. (That's assuming you have a stereo setup and don't need the second channel for something else.) Another way is to compare the sample rate with the PC clock. That will correct for any long term drift but may not track shorter transients. -- 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. ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Hi The 1/F noise vs beat note “amplification” tradeoff is what pushes me up to 10 Hz rather than staying down around 1 Hz with most setups. It’s also a rational offset to achieve at 10 MHz with common OCXO’s. Once you get past about 20 Hz, your OCXO choices diminish. Bob On Oct 12, 2014, at 7:57 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Increasing the beat frequency to find a balance between 1/f noise and f/delta-f amplification may be worth doing and have been seen done to find optimum performance. If you use hard limiters or audio channels to achieve it is however a little detail. The benefit of audio channels is that the A/B channels does not disperse out in time, such that you loose cross-correlation of transfer oscillator noise. Some AD inputs may need to be modified to remove DC-blocking cap. Not all ADCs is happy with this. Some boards already have that and do DC-removal in digital filters. Cheers, Magnus On 10/12/2014 11:09 PM, Bob Camp wrote: HI A little more information: If you are doing the ADC thing, you still need to estimate zero crossings. In all likelihood you would be doing bandpass filtering first (say 8 Hz to 12 Hz) on your 10 Hz note. Next you would do some sort of estimator to get the zero cross. A curve fit is one sort of estimator, there are others. A simple straight line fit over 4 or so points might do it. A higher order fit over a few more points is possible. Why does that matter? The fit improves your accuracy quite a bit. It also reduces your vulnerability to odd single sample issues like popcorn noise. Since you are running at a very low frequency 1/f noise can be an issue. Bob On Oct 12, 2014, at 2:37 PM, Hal Murray hmur...@megapathdsl.net wrote: anders.e.e.wal...@gmail.com said: Does it matter that the ADC in the sound-card is probably clocked by a crystal clock that is 50ppm off and has bad ADEV? You can calibrate the clock on the ADC. One way is to feed a known reference frequency in on the other channel. (That's assuming you have a stereo setup and don't need the second channel for something else.) Another way is to compare the sample rate with the PC clock. That will correct for any long term drift but may not track shorter transients. -- 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. ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Bob, I know, and I know you know. Just let others see how things connect up. Still have some 10.000110 MHz OCXOs lying around. Cheers, Magnus On 10/13/2014 02:15 AM, Bob Camp wrote: Hi The 1/F noise vs beat note “amplification” tradeoff is what pushes me up to 10 Hz rather than staying down around 1 Hz with most setups. It’s also a rational offset to achieve at 10 MHz with common OCXO’s. Once you get past about 20 Hz, your OCXO choices diminish. Bob On Oct 12, 2014, at 7:57 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Increasing the beat frequency to find a balance between 1/f noise and f/delta-f amplification may be worth doing and have been seen done to find optimum performance. If you use hard limiters or audio channels to achieve it is however a little detail. The benefit of audio channels is that the A/B channels does not disperse out in time, such that you loose cross-correlation of transfer oscillator noise. Some AD inputs may need to be modified to remove DC-blocking cap. Not all ADCs is happy with this. Some boards already have that and do DC-removal in digital filters. Cheers, Magnus On 10/12/2014 11:09 PM, Bob Camp wrote: HI A little more information: If you are doing the ADC thing, you still need to estimate zero crossings. In all likelihood you would be doing bandpass filtering first (say 8 Hz to 12 Hz) on your 10 Hz note. Next you would do some sort of estimator to get the zero cross. A curve fit is one sort of estimator, there are others. A simple straight line fit over 4 or so points might do it. A higher order fit over a few more points is possible. Why does that matter? The fit improves your accuracy quite a bit. It also reduces your vulnerability to odd single sample issues like popcorn noise. Since you are running at a very low frequency 1/f noise can be an issue. Bob On Oct 12, 2014, at 2:37 PM, Hal Murray hmur...@megapathdsl.net wrote: anders.e.e.wal...@gmail.com said: Does it matter that the ADC in the sound-card is probably clocked by a crystal clock that is 50ppm off and has bad ADEV? You can calibrate the clock on the ADC. One way is to feed a known reference frequency in on the other channel. (That's assuming you have a stereo setup and don't need the second channel for something else.) Another way is to compare the sample rate with the PC clock. That will correct for any long term drift but may not track shorter transients. -- 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. ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Hi If odd “almost 10 MHz OCXO’s were more common, you could indeed have a bit more freedom on the offset. DDS is sometimes used. DDS spurs (which can be *very* close in) can be both hard to predict and hard to spot in the data. An OCXO is a much better bet unless you have a lot of time on your hands or a really good spectrum analyzer. Much easier to get a $20 Trimble OCXO at auction and ground the EFC pin…. Bob On Oct 12, 2014, at 8:25 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob, I know, and I know you know. Just let others see how things connect up. Still have some 10.000110 MHz OCXOs lying around. Cheers, Magnus On 10/13/2014 02:15 AM, Bob Camp wrote: Hi The 1/F noise vs beat note “amplification” tradeoff is what pushes me up to 10 Hz rather than staying down around 1 Hz with most setups. It’s also a rational offset to achieve at 10 MHz with common OCXO’s. Once you get past about 20 Hz, your OCXO choices diminish. Bob On Oct 12, 2014, at 7:57 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Increasing the beat frequency to find a balance between 1/f noise and f/delta-f amplification may be worth doing and have been seen done to find optimum performance. If you use hard limiters or audio channels to achieve it is however a little detail. The benefit of audio channels is that the A/B channels does not disperse out in time, such that you loose cross-correlation of transfer oscillator noise. Some AD inputs may need to be modified to remove DC-blocking cap. Not all ADCs is happy with this. Some boards already have that and do DC-removal in digital filters. Cheers, Magnus On 10/12/2014 11:09 PM, Bob Camp wrote: HI A little more information: If you are doing the ADC thing, you still need to estimate zero crossings. In all likelihood you would be doing bandpass filtering first (say 8 Hz to 12 Hz) on your 10 Hz note. Next you would do some sort of estimator to get the zero cross. A curve fit is one sort of estimator, there are others. A simple straight line fit over 4 or so points might do it. A higher order fit over a few more points is possible. Why does that matter? The fit improves your accuracy quite a bit. It also reduces your vulnerability to odd single sample issues like popcorn noise. Since you are running at a very low frequency 1/f noise can be an issue. Bob On Oct 12, 2014, at 2:37 PM, Hal Murray hmur...@megapathdsl.net wrote: anders.e.e.wal...@gmail.com said: Does it matter that the ADC in the sound-card is probably clocked by a crystal clock that is 50ppm off and has bad ADEV? You can calibrate the clock on the ADC. One way is to feed a known reference frequency in on the other channel. (That's assuming you have a stereo setup and don't need the second channel for something else.) Another way is to compare the sample rate with the PC clock. That will correct for any long term drift but may not track shorter transients. -- 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. ___ 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 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.
