[time-nuts] eLoran for GPS backup
The Brits are turning their Loran system back on to protect against GPS outages from jamming or space weather: http://www.gpsworld.com/uk-switches-on-eloran-for-backup-in-the-english-channel/ -- Chuck Forsberg WA7KGX c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] Silicon Chip 2.5GHz 12 Digit Frequency Counter
Hi, The January issue of the article is now available so it would be interesting to get further comments from members. Previous comments were generally very critical of this Jim Rowe designed unit and one in particular commented on the non availability of the source code for some of the projects. The .asm and hex files are available free from http://www.siliconchip.com.au/Shop/6 so it would be interesting to hear from those who are programmers what they think of it. I do not need to build the unit but down the track may do so just for the experience and to compare its performance against various HP counters I have - some people have no sense!! Merv VK6BMT ___ 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] eLoran for GPS backup
Actually it has been on all the time - this is just a more extensive implementation of the (formerly experimental) e-loran 'add-in' to target high usage areas. Paul Reeves G8GJA -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chuck Forsberg WA7KGX N2469R Sent: 09 January 2013 08:05 To: ExTek; time-nuts Subject: [time-nuts] eLoran for GPS backup The Brits are turning their Loran system back on to protect against GPS outages from jamming or space weather: http://www.gpsworld.com/uk-switches-on-eloran-for-backup-in-the-english-channel/ -- Chuck Forsberg WA7KGX c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] CPU clock jitter
Message: 1 I was thinking more along the lines of large jitter in the CPU clock. A clock shortened by 1/8th cycle could play havoc with CPU operation. Of course you could do the experiment to see what happens. Or you could divide by 10 and only worry about the rest of the problems. Simon Date: Tue, 08 Jan 2013 08:27:18 -0800 From: Ed Breya e...@telight.com To: time-nuts@febo.com Subject: Re: [time-nuts] (no subject) Message-ID: 50ec48e6.5020...@telight.com Content-Type: text/plain; charset=ISO-8859-1; format=flowed Yes, that's true, Simon, but remember the initial goals of simplicity and long term phase coherence, while jitter doesn't matter so much. The longer term average frequency ratio should be right on, while comparing at any particular cycles it would be awful. Ed -- Message: 2 Date: Tue, 08 Jan 2013 20:56:32 +0100 From: Magnus Danielson mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] (no subject) Message-ID: 50ec79f0.3020...@rubidium.dyndns.org Content-Type: text/plain; charset=ISO-8859-1; format=flowed On 01/08/2013 09:08 AM, M. Simon wrote: To reduce cycle to cycle jitter I think a divide by 10 is in order (/5, /2). And if you can arrange it the MCU should be a little slow. The cycle jitter doesn't change in time-amplitude by division, it's just the jitter relative to the period which changes with the division. Cheers, Magnus Engineering is the art of making what you want from what you can get at a profit. ___ 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] eLoran for GPS backup
Hi Chuck, It never went off!! The French are spear-heading this. An experimental eLoran station was run from Rugby (GBR site) before it finally closed then the gear was relocated to be run by VT Communications, now Babcock I believe, based on Anthorn (south bank of the Solway Firth). This uses the gear that was originally destinded for Loop Head in Ireland (but cancelled due to local protest) as the 3rd slave on the Lessay chain. Anthorn is not ideal but it was already a Mil VLF (19.6kHz) site. The original experiment was mounted from Trinity House, the Lights an Nav authority for the UK, at their base in Harwich just across the river from me. The French have attempted to resurect the Mediteranean chain but have had no interest. Most of the financers of the Baltic Sylt chain do not seem enthusiastic but it remains on (I believe subsidised by the French) Alan G3NYK - Original Message - From: Chuck Forsberg WA7KGX N2469R c...@omen.com To: ExTek gatesja-l...@eskimo.com; time-nuts time-nuts@febo.com Sent: Wednesday, January 09, 2013 8:04 AM Subject: [time-nuts] eLoran for GPS backup The Brits are turning their Loran system back on to protect against GPS outages from jamming or space weather: http://www.gpsworld.com/uk-switches-on-eloran-for-backup-in-the-english-channel/ -- Chuck Forsberg WA7KGX c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] Interval Timer Recommendation
Hi There are a number of counters that are a lot better than what you have. There's also a limited amount of money in the universe. I'd suggest setting a rational budget and time frame. This is all used gear. You *might* get a perfect one that never ever breaks. More likely you will need to get a couple and swap things around. I'd plan on buying 3 or 4 with what ever the budget is. If you get lucky, you come in under budget. Less fancy: 5334 - couple of ns resolution, nice and small, B is *very* different than the A so get one or the other 5335 - faster bigger heavier, one ns resolution. both should be around $100 before shipping. Very cool: 53131 500 ps resolution 53132 150 ps resolution both have displays that can wear out. They are no longer supported by HP so you *might* find somebody dumping them. Hard to find for less than $800. Big and heavy: 5371, 5372 same resolution as the 53132 They don't show up much. I've seen them for $200. You probably should expect to pay $400. Expect shipping to be non-trivial. High end: SR620 5370 53230a All are in the 20 ps range. You do see 5370's for $200. More commonly you see them for quite a bit more. The 620's show up anywhere between $800 and $3000. The 53230a is brand new with a warranty from Agilent for about $3700. That's just one set of parts. There are others. There are more issues than just price to consider. The 5371 is a *big* piece of gear. The 53xxx boxes are all small enough to carry around. Lots of choices. Bob On Jan 8, 2013, at 9:50 PM, dlewis6767 dlewis6...@austin.rr.com wrote: Hi Magnus, good day. Thanks for the thoughts, ...that was pretty much where I was headed. I think I will hold out a while for a 5370, watch eBay, see if a reasonably priced unit pops up. If anyone has one for sale for a nice price, please let me know. -Don -- From: Magnus Danielson mag...@rubidium.dyndns.org Sent: Tuesday, January 08, 2013 7:42 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Interval Timer Recommendation Hi Don, On 01/09/2013 02:32 AM, dlewis6767 wrote: I am looking to upgrade my older HP 5245L counter/ timer to one with greater resolution. In my home lab, I have been collecting GPS timing modules (receivers) and just want to start measuring their 1PPS jitter, etc. over one period. The 5245L will only measure to 100ns with a 1 second pulse (.1us period at 1 period). I was looking at the HP5370/ 71/ 72 series counter/ timers. What is the best resolution they can provide for a one second pulse (over one period)? Do you have any recommendation as to which one of the three models is the better unit? (Their display technology, age and cost not withstanding.) All three models seem greatly overstated in price on eBay, seems, too. Not sure why, ...just supply and demand; I presume. Thank you for your advice; I appreciate your thoughts. Of the given set, the HP5370 will have much better single shot resolution compared to the HP5371/5372. The later is better at recording high rate events. I have both HP5370 and HP5372 as they fill different purposes. I also have counters of better performance than these. Trouble is, with PPS signals you experience jitter such that a 1 ns resolution of a HP5335 will suffice for most usages. 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. ___ 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] Interval Timer Recommendation
Thank you Bob, Ed, Magnus , ..and all. Excellent reviews, ...detailed and clear. I REALLY do appreciate it. HP has turned out so much equipment over the years, it is often good to see a comparison. This was excellent. I'll wait for a good deal, and don the road bid alongside many of you , I presume. :-) I may opt for one of the better units, ...as this disease progresses. -Don -- From: Bob Camp li...@rtty.us Sent: Wednesday, January 09, 2013 6:43 AM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Interval Timer Recommendation Hi There are a number of counters that are a lot better than what you have. There's also a limited amount of money in the universe. I'd suggest setting a rational budget and time frame. This is all used gear. You *might* get a perfect one that never ever breaks. More likely you will need to get a couple and swap things around. I'd plan on buying 3 or 4 with what ever the budget is. If you get lucky, you come in under budget. Less fancy: 5334 - couple of ns resolution, nice and small, B is *very* different than the A so get one or the other 5335 - faster bigger heavier, one ns resolution. both should be around $100 before shipping. Very cool: 53131 500 ps resolution 53132 150 ps resolution both have displays that can wear out. They are no longer supported by HP so you *might* find somebody dumping them. Hard to find for less than $800. Big and heavy: 5371, 5372 same resolution as the 53132 They don't show up much. I've seen them for $200. You probably should expect to pay $400. Expect shipping to be non-trivial. High end: SR620 5370 53230a All are in the 20 ps range. You do see 5370's for $200. More commonly you see them for quite a bit more. The 620's show up anywhere between $800 and $3000. The 53230a is brand new with a warranty from Agilent for about $3700. That's just one set of parts. There are others. There are more issues than just price to consider. The 5371 is a *big* piece of gear. The 53xxx boxes are all small enough to carry around. Lots of choices. Bob On Jan 8, 2013, at 9:50 PM, dlewis6767 dlewis6...@austin.rr.com wrote: Hi Magnus, good day. Thanks for the thoughts, ...that was pretty much where I was headed. I think I will hold out a while for a 5370, watch eBay, see if a reasonably priced unit pops up. If anyone has one for sale for a nice price, please let me know. -Don -- From: Magnus Danielson mag...@rubidium.dyndns.org Sent: Tuesday, January 08, 2013 7:42 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Interval Timer Recommendation Hi Don, On 01/09/2013 02:32 AM, dlewis6767 wrote: I am looking to upgrade my older HP 5245L counter/ timer to one with greater resolution. In my home lab, I have been collecting GPS timing modules (receivers) and just want to start measuring their 1PPS jitter, etc. over one period. The 5245L will only measure to 100ns with a 1 second pulse (.1us period at 1 period). I was looking at the HP5370/ 71/ 72 series counter/ timers. What is the best resolution they can provide for a one second pulse (over one period)? Do you have any recommendation as to which one of the three models is the better unit? (Their display technology, age and cost not withstanding.) All three models seem greatly overstated in price on eBay, seems, too. Not sure why, ...just supply and demand; I presume. Thank you for your advice; I appreciate your thoughts. Of the given set, the HP5370 will have much better single shot resolution compared to the HP5371/5372. The later is better at recording high rate events. I have both HP5370 and HP5372 as they fill different purposes. I also have counters of better performance than these. Trouble is, with PPS signals you experience jitter such that a 1 ns resolution of a HP5335 will suffice for most usages. 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. ___ 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] Interval Timer Recommendation
Hi Keep in mind that the good prices are generally for gear that is in the don't know if it works at all category. The prices go up quickly for stuff that has had even basic checks run on it. It's rare to find any of this stuff with a believable iron clad guarantee / certification that it runs 100% to original specs. I've seen a lot of gear with cal stickers on it that doesn't do this or that correctly... Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of dlewis6767 Sent: Wednesday, January 09, 2013 8:07 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Interval Timer Recommendation Thank you Bob, Ed, Magnus , ..and all. Excellent reviews, ...detailed and clear. I REALLY do appreciate it. HP has turned out so much equipment over the years, it is often good to see a comparison. This was excellent. I'll wait for a good deal, and don the road bid alongside many of you , I presume. :-) I may opt for one of the better units, ...as this disease progresses. -Don -- From: Bob Camp li...@rtty.us Sent: Wednesday, January 09, 2013 6:43 AM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Interval Timer Recommendation Hi There are a number of counters that are a lot better than what you have. There's also a limited amount of money in the universe. I'd suggest setting a rational budget and time frame. This is all used gear. You *might* get a perfect one that never ever breaks. More likely you will need to get a couple and swap things around. I'd plan on buying 3 or 4 with what ever the budget is. If you get lucky, you come in under budget. Less fancy: 5334 - couple of ns resolution, nice and small, B is *very* different than the A so get one or the other 5335 - faster bigger heavier, one ns resolution. both should be around $100 before shipping. Very cool: 53131 500 ps resolution 53132 150 ps resolution both have displays that can wear out. They are no longer supported by HP so you *might* find somebody dumping them. Hard to find for less than $800. Big and heavy: 5371, 5372 same resolution as the 53132 They don't show up much. I've seen them for $200. You probably should expect to pay $400. Expect shipping to be non-trivial. High end: SR620 5370 53230a All are in the 20 ps range. You do see 5370's for $200. More commonly you see them for quite a bit more. The 620's show up anywhere between $800 and $3000. The 53230a is brand new with a warranty from Agilent for about $3700. That's just one set of parts. There are others. There are more issues than just price to consider. The 5371 is a *big* piece of gear. The 53xxx boxes are all small enough to carry around. Lots of choices. Bob On Jan 8, 2013, at 9:50 PM, dlewis6767 dlewis6...@austin.rr.com wrote: Hi Magnus, good day. Thanks for the thoughts, ...that was pretty much where I was headed. I think I will hold out a while for a 5370, watch eBay, see if a reasonably priced unit pops up. If anyone has one for sale for a nice price, please let me know. -Don -- From: Magnus Danielson mag...@rubidium.dyndns.org Sent: Tuesday, January 08, 2013 7:42 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Interval Timer Recommendation Hi Don, On 01/09/2013 02:32 AM, dlewis6767 wrote: I am looking to upgrade my older HP 5245L counter/ timer to one with greater resolution. In my home lab, I have been collecting GPS timing modules (receivers) and just want to start measuring their 1PPS jitter, etc. over one period. The 5245L will only measure to 100ns with a 1 second pulse (.1us period at 1 period). I was looking at the HP5370/ 71/ 72 series counter/ timers. What is the best resolution they can provide for a one second pulse (over one period)? Do you have any recommendation as to which one of the three models is the better unit? (Their display technology, age and cost not withstanding.) All three models seem greatly overstated in price on eBay, seems, too. Not sure why, ...just supply and demand; I presume. Thank you for your advice; I appreciate your thoughts. Of the given set, the HP5370 will have much better single shot resolution compared to the HP5371/5372. The later is better at recording high rate events. I have both HP5370 and HP5372 as they fill different purposes. I also have counters of better performance than these. Trouble is, with PPS signals you experience jitter such that a 1 ns resolution of a HP5335 will suffice for most usages. 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] eLoran for GPS backup
In message 3B5BC99D4C814337985A6DE70F6AAC60@gnat, Alan Melia writes: Most of the financers of the Baltic Sylt chain do not seem enthusiastic but it remains on (I believe subsidised by the French) I belive UK and France carries the entire cost of the NELS chains now. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Interval Timer Recommendation
On 01/09/2013 05:39 AM, Ed Palmer wrote: In the past there has been much discussion on this list regarding the relative strengths and weaknesses of the 5370 (20ps resolution) and the 5371/5372 (150ps resolution) units. There are other units that have even better resolution, but they tend to be pricey and/or more specialized. The 5371/5372 has a 200 ps resolution. They where designed to allow extension to 100 ps resolution. The FLASH-interpolators have 200 ps steps, sufficiently good trigger such that you get 150 ps resolution performance on the white-noise limit. 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.
[time-nuts] Ault SW-305 wiring colours
I bought a Thunderbolt via TAPR some time ago which came complete with an Ault SW-305 PSU. For some reason I can't find the documentation that came with it and don't have the wiring colour codes. A diligent search of the internet hasn't thrown up anything -- can any kind soul please assist? There are six wires emerging from the supply: red, brown, green, black, white and blue. I seem to recall that red is +12V and black is -12V but that leaves four wires for one rail and ground... 73 John GW4FRX ___ 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] Ault SW-305 wiring colours
Hi John The information below was posted to the list by another member back in 2008. I never used the SW305 power supply with mine and haven't confirmed these connections, so the Check before use is still very good advice:-) Regards Nigel GM8PZR --- CHECK BEFORE USE SW305 PSU wiring... Case Ground --- Brown +5 Volts --- Green +12 Volts --- Red -12 Volts --- Black Common --- White --- In a message dated 09/01/2013 19:22:46 GMT Standard Time, honey...@outlook.com writes: I bought a Thunderbolt via TAPR some time ago which came complete with an Ault SW-305 PSU. For some reason I can't find the documentation that came with it and don't have the wiring colour codes. A diligent search of the internet hasn't thrown up anything -- can any kind soul please assist? There are six wires emerging from the supply: red, brown, green, black, white and blue. I seem to recall that red is +12V and black is -12V but that leaves four wires for one rail and ground... 73 John GW4FRX ___ 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] Ault SW-305 wiring colours
I bought a Thunderbolt via TAPR some time ago which came complete with an Ault SW-305 PSU. For some reason I can't find the documentation that came with it and don't have the wiring colour codes. A diligent search of the internet hasn't thrown up anything -- can any kind soul please assist? There are six wires emerging from the supply: red, brown, green, black, white and blue. I seem to recall that red is +12V and black is -12V but that leaves four wires for one rail and ground... Hi John, The Ault SW-305 had inconsistent colors, batch to batch. I could send you the colors for two versions I have here, but it would be best for you to ignore color and trust your ohm/voltmeter. The TBolt only needs 4 wires (+12,gnd,+5,-12). See also: http://www.leapsecond.com/pages/tapr-tbolt/ http://www.leapsecond.com/pages/tbolt/power.htm http://www.leapsecond.com/pages/tbolt/conn.htm http://www.leapsecond.com/pages/tbolt/noise.htm If you have more questions let me know, off-line (I was the one who created all the TAPR TBolt kits). /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Interval Timer Recommendation
and don't forget the PM6681 (50pS) On Wed, Jan 9, 2013 at 7:29 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 01/09/2013 05:39 AM, Ed Palmer wrote: In the past there has been much discussion on this list regarding the relative strengths and weaknesses of the 5370 (20ps resolution) and the 5371/5372 (150ps resolution) units. There are other units that have even better resolution, but they tend to be pricey and/or more specialized. The 5371/5372 has a 200 ps resolution. They where designed to allow extension to 100 ps resolution. The FLASH-interpolators have 200 ps steps, sufficiently good trigger such that you get 150 ps resolution performance on the white-noise limit. Cheers, Magnus __**_ 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] Interval Timer Recommendation
On 1/9/2013 12:48 PM, Azelio Boriani wrote: and don't forget the PM6681 (50pS) The PM6681 was sold by Fluke/Philips. The same counter is also occasionally seen as the Pendulum CNT-81. Additional good features: small, light, and quiet. On Wed, Jan 9, 2013 at 7:29 PM, Magnus Danielsonmag...@rubidium.dyndns.org wrote: On 01/09/2013 05:39 AM, Ed Palmer wrote: In the past there has been much discussion on this list regarding the relative strengths and weaknesses of the 5370 (20ps resolution) and the 5371/5372 (150ps resolution) units. There are other units that have even better resolution, but they tend to be pricey and/or more specialized. The 5371/5372 has a 200 ps resolution. They where designed to allow extension to 100 ps resolution. The FLASH-interpolators have 200 ps steps, sufficiently good trigger such that you get 150 ps resolution performance on the white-noise limit. 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.
[time-nuts] Simple method for comparing 10 MHz signals
I kept putting off buying a nice counter and finally decided to try a phase detector circuit to compare 10 MHz standards. It’s not novel, but I like the results so far. It lets me see things I couldn’t see before. I thought the idea might be useful to some of us who are equipment-limited. The graph shows an LPRO-101 as the white trace and an FE-5680 as the red trace, both compared to a simple GPS standard. The graph is just an example of a data collection run and doesn’t represent any particular level of performance. It does show a lot of common mode change, indicating the GPS is changing during the run. Maybe I should say probably changing. The whole breadboard circuit has 4 IC’s. The blue trace is a measurement of the case temperature of the GPS standard. The circuit uses 1/2 of a 74HC4015 4 bit shift register for each channel. The D input of each 74HC4015 gets the Q-D output inverted by a gate from a 74HC04, forming a divide by 8 “Johnson counter”. At the beginning of a run all 74HC4015’s are simultaneously reset. 74HC86 XOR gates are used as phase detectors. One input of each XOR connects to the Q-A output of the GPS 74HC4015 and the other input connects to the Q-C output of the LPRO-101 or FE5680 74HC4015. Using different taps gets the initial state of the XOR output close to 1/2 scale and known slope. The average value of the XOR goes from 0 to full scale for a phase change of 180 degrees. 180 degrees of the divide by 8 corresponds to 400 nsec, +/- 2 cycles of 10 MHz. I already had a LabJack U6 data acquisition unit, which has several analog inputs and digital I/O. Other similar products are available and inexpensive. LabJack has free data-collection software so you can get a file usable by Excel or whatever without writing any code. For me it was easy and cheaper to convert the phase signal to a voltage and read it. This approach isn’t useful for comparing PPS signals and isn’t as accurate as using a good TIC. I’m looking forward to the TIC design in progress, but this project seems useful for now.attachment: Phase-8-4015.GIF___ 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] Simple method for comparing 10 MHz signals
Hi Bob, Thanks for sharing that. Many of the atomic clock phase comparators from the 70's and 80's were based on this time-honored technique. The use of different taps/scales is clever. Note that once you have an ascii data file from LabJack you can feed that into John's TimeLab program for batch or real-time updates of phase, frequency, and stability (e.g., ADEV). If you need something more automated let me know; I wrote hands-free acquisition code for the LabJack once (bypassing their GUI). /tvb - Original Message - From: Bob Quenelle bobqh...@live.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, January 09, 2013 4:29 PM Subject: [time-nuts] Simple method for comparing 10 MHz signals I kept putting off buying a nice counter and finally decided to try a phase detector circuit to compare 10 MHz standards. It’s not novel, but I like the results so far. It lets me see things I couldn’t see before. I thought the idea might be useful to some of us who are equipment-limited. The graph shows an LPRO-101 as the white trace and an FE-5680 as the red trace, both compared to a simple GPS standard. The graph is just an example of a data collection run and doesn’t represent any particular level of performance. It does show a lot of common mode change, indicating the GPS is changing during the run. Maybe I should say probably changing. The whole breadboard circuit has 4 IC’s. The blue trace is a measurement of the case temperature of the GPS standard. The circuit uses 1/2 of a 74HC4015 4 bit shift register for each channel. The D input of each 74HC4015 gets the Q-D output inverted by a gate from a 74HC04, forming a divide by 8 “Johnson counter”. At the beginning of a run all 74HC4015’s are simultaneously reset. 74HC86 XOR gates are used as phase detectors. One input of each XOR connects to the Q-A output of the GPS 74HC4015 and the other input connects to the Q-C output of the LPRO-101 or FE5680 74HC4015. Using different taps gets the initial state of the XOR output close to 1/2 scale and known slope. The average value of the XOR goes from 0 to full scale for a phase change of 180 degrees. 180 degrees of the divide by 8 corresponds to 400 nsec, +/- 2 cycles of 10 MHz. I already had a LabJack U6 data acquisition unit, which has several analog inputs and digital I/O. Other similar products are available and inexpensive. LabJack has free data-collection software so you can get a file usable by Excel or whatever without writing any code. For me it was easy and cheaper to convert the phase signal to a voltage and read it. This approach isn’t useful for comparing PPS signals and isn’t as accurate as using a good TIC. I’m looking forward to the TIC design in progress, but this project seems useful for now. ___ 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] Simple method for comparing 10 MHz signals
Bob Quenelle wrote: I kept putting off buying a nice counter and finally decided to try a phase detector circuit to compare 10 MHz standards. Itâs not novel, but You might want to try this phase detector instead of reinventing the wheel: http://www.analog.com/static/imported-files/data_sheets/AD9901.pdf Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Interval Timer Recommendation
On 01/10/2013 12:02 AM, Rex wrote: On 1/9/2013 12:48 PM, Azelio Boriani wrote: and don't forget the PM6681 (50pS) The PM6681 was sold by Fluke/Philips. The same counter is also occasionally seen as the Pendulum CNT-81. Additional good features: small, light, and quiet. A bit more history then. Philips had a sub-sidary called Philips Industrier Järfälla, located just outside Stockholm. They made amongst other things OCXOs and counters, but a numerous of other measuring gadgets. As Philips merged with Fluke for instruments, the Philips Industrier measurments gear also re-occured in their Fluke variant for the US market. They kept their PM model numbers. As Philips was retracting from the market, they sold of the TF reminder of Philips Industrier and that was named Pendulum, which kept the connection with Fluke. This meant that the new counters coming out also came out in their Fluke variants. However, pendulum decided to strike out the PM66 prefix (for counters) for their Pendulum branded gear and had different prefixes such as CNT-80/81/85/90/90XL/91, GPS-12/88/89 and WM-10/11. Pendulum was sold off to SpectraCom, and it was run as a separate business for some time, but eventually the old company was dismantled and Pendulum remains as a brand within SpectraCom. The product range exists, except for the CNT-8x series which died off then the last of the custom counter chips ran out, besides what was kept for service of course. The CNT-9x series uses a FPGA as counter core. Today only a few of the original staff remains with SpectraCom. The CNT-90 has also appeared in Tektronix format. I had some exchange with them as they where local to me. 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.
[time-nuts] Phase Detector was -- Simple method for comparing 10 MHz signals
There is another way. Take your reference signal and divide it by convenient steps. Apply the ref and the divided ref to the input pins of a very fast 574. Use a high output current 245 (24 or 32 ma drive) with resistor inputs (to decouple from the 574) to drive an LED bar (or RC integrator). The 574 will run faster if the loading is light and resistive. Clock the 574 with the signal whose phase you are trying to measure. Or a divided down version of the same. The two signals should be integral multiples of each other. That includes the divided down versions. You can now tell if your test signal is skipping phases of your ref. Example: 10 MHz 1 MHz 100KHz into the 574. Clock it with 32Hz from your 32,768 Hz clock osc. Adjust your 32768 until the 10MHz LED rarely blinks. Your 32768 is now better than 1E-7 if your 10MHz is on the button. At 20 ppm (the typical limit of 32768 oscillators) the 100KHz LED blinks twice a second. Using an XOR requires you to have square waves. The above only requires edge alignment (it is in effect a type 2 phase detector). And you are not limited to signals whose frequencies are nearly equal. They need only be roughly phase coherent. Simon Message: 6 Date: Wed, 9 Jan 2013 16:29:32 -0800 From: Bob Quenelle bobqh...@live.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Simple method for comparing 10 MHz signals Message-ID: snt125-ds15824f3cf1b6c9f0b40b93b2...@phx.gbl Content-Type: text/plain; charset=utf-8 I kept putting off buying a nice counter and finally decided to try a phase detector circuit to compare 10 MHz standards. It?s not novel, but I like the results so far. It lets me see things I couldn?t see before. I thought the idea might be useful to some of us who are equipment-limited. The graph shows an LPRO-101 as the white trace and an FE-5680 as the red trace, both compared to a simple GPS standard. The graph is just an example of a data collection run and doesn?t represent any particular level of performance. It does show a lot of common mode change, indicating the GPS is changing during the run. Maybe I should say probably changing. The whole breadboard circuit has 4 IC?s. The blue trace is a measurement of the case temperature of the GPS standard. The circuit uses 1/2 of a 74HC4015 4 bit shift register for each channel. The D input of each 74HC4015 gets the Q-D output inverted by a gate from a 74HC04, forming a divide by 8 ?Johnson counter?. At the beginning of a run all 74HC4015?s are simultaneously reset. 74HC86 XOR gates are used as phase detectors. One input of each XOR connects to the Q-A output of the GPS 74HC4015 and the other input connects to the Q-C output of the LPRO-101 or FE5680 74HC4015. Using different taps gets the initial state of the XOR output close to 1/2 scale and known slope. The average value of the XOR goes from 0 to full scale for a phase change of 180 degrees. 180 degrees of the divide by 8 corresponds to 400 nsec, +/- 2 cycles of 10 MHz. I already had a LabJack U6 data acquisition unit, which has several analog inputs and digital I/O. Other similar products are available and inexpensive. LabJack has free data-collection software so you can get a file usable by Excel or whatever without writing any code. For me it was easy and cheaper to convert the phase signal to a voltage and read it. This approach isn?t useful for comparing PPS signals and isn?t as accurate as using a good TIC. I?m looking forward to the TIC design in progress, but this project seems useful for now. -- next part -- A non-text attachment was scrubbed... Name: Phase-8-4015.GIF Type: image/gif Size: 18956 bytes Desc: not available URL: http://www.febo.com/pipermail/time-nuts/attachments/20130109/181e7fca/attachment.gif Engineering is the art of making what you want from what you can get at a profit. ___ 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.
