Re: [time-nuts] Divider circuit for Rubidium Standard
Hi On May 20, 2015, at 11:27 PM, Alex Pummer a...@pcscons.com wrote: once upon the time at Gigatronics we compared logic devices noise and found that TTL were the quietest 73 KJ6UHN Alex Before the 74AC stuff came along, some flavor of TTL was the best bet. With TTL you needed to be a bit carefull about just what family (and in some cases manufacturer) you used. All that picky stuff has pretty much gone away with fast silicon CMOS, at least among the major outfits. Bob On 5/20/2015 3:15 PM, Richard (Rick) Karlquist wrote: On 5/20/2015 11:22 AM, Magnus Danielson wrote: The older HP counter manuals explained it very nicely too, as they illustrated the slew-rate amplitude noise to time-noise conversion. What do amazes me is the fact that I've yet to see a counter input channel which takes care to square up the signal properly, they rather provide the comparator after the obvious damping and AC-blocking conditioning. I can't even recall that there where much such shaping as a side-product. The counter front ends seem to be modeled after scope front ends and scope triggering circuits, where you can adjust the triggering level. Any jitter in the triggering would normally only affect the interpolator. The interpolators in general were no great shakes, so the triggering wasn't the limiting factor. Now, remind me why ECL is lousy, I can't recall there being very high gain in them, but fairly high bandwidth and they stay in the linear operation region. Magnus ___ ECL is bad because the voltage swing is low; because as you say, a lot of the circuitry is in the active region all the time, and because the current source in the emitters generates a lot of noise. In the early 1990's, I thought I had proved that the high ECL noise was mostly common mode and that you could reduce it 20 dB by using a transformer to couple the output. Alternately, a good differential amplifier with high CMRR would do the trick. I had actual measurements to back up this theory. Subsequently, other people tried to reproduce this and could not. By that time, I had moved on and didn't have the bandwidth to continue to own the problem. It would make a nice project for some time-nut to prove or disprove my hypothesis regarding ECL. ECL line receivers as squarers are not as bad as comparators, but are much noisier than 74AC. Rick Karlquist N6RK 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. ___ time-nuts mailing 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] Lucent/Symmetricom Z3810AS, KS24361 - They're Back
Looks like another shipment for those that might have missed them before. Item 221777430088 No connection to seller except satisfied customer. Joe ___ time-nuts mailing 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] Lucent/Symmetricom Z3810AS, KS24361 - They're Back
Is there a discussion somewhere on these units and how to get them working ? 73, Dick, W1KSZ On 5/20/2015 5:47 AM, J. L. Trantham wrote: Looks like another shipment for those that might have missed them before. Item 221777430088 No connection to seller except satisfied customer. Joe ___ time-nuts mailing 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] Divider circuit for Rubidium Standard
On 05/21/2015 12:15 AM, Richard (Rick) Karlquist wrote: On 5/20/2015 11:22 AM, Magnus Danielson wrote: The older HP counter manuals explained it very nicely too, as they illustrated the slew-rate amplitude noise to time-noise conversion. What do amazes me is the fact that I've yet to see a counter input channel which takes care to square up the signal properly, they rather provide the comparator after the obvious damping and AC-blocking conditioning. I can't even recall that there where much such shaping as a side-product. The counter front ends seem to be modeled after scope front ends and scope triggering circuits, where you can adjust the triggering level. Any jitter in the triggering would normally only affect the interpolator. The interpolators in general were no great shakes, so the triggering wasn't the limiting factor. Depends on the signal. Now, remind me why ECL is lousy, I can't recall there being very high gain in them, but fairly high bandwidth and they stay in the linear operation region. Magnus ___ ECL is bad because the voltage swing is low; because as you say, a lot of the circuitry is in the active region all the time, and because the current source in the emitters generates a lot of noise. Yes, it is bound to have 1/f noise with it's 50 Ohm current load. I was thinking about the continuous current, as I do know of the gating effect. Today there is other interface standards having lower swings than ECL. In the early 1990's, I thought I had proved that the high ECL noise was mostly common mode and that you could reduce it 20 dB by using a transformer to couple the output. Alternately, a good differential amplifier with high CMRR would do the trick. I had actual measurements to back up this theory. Subsequently, other people tried to reproduce this and could not. By that time, I had moved on and didn't have the bandwidth to continue to own the problem. It would make a nice project for some time-nut to prove or disprove my hypothesis regarding ECL. ECL line receivers as squarers are not as bad as comparators, but are much noisier than 74AC. Interesting. Don't have a lot of ECL lying around, but some toys that might measure things. 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] Lucent/Symmetricom Z3810AS, KS24361 - They're Back
Hi Yes indeed. If you go back into the archives around last January, you should find everything you would need to get a pair running. Bob On May 21, 2015, at 4:36 PM, Richard Solomon w1...@earthlink.net wrote: Is there a discussion somewhere on these units and how to get them working ? 73, Dick, W1KSZ On 5/20/2015 5:47 AM, J. L. Trantham wrote: Looks like another shipment for those that might have missed them before. Item 221777430088 No connection to seller except satisfied customer. Joe ___ time-nuts mailing 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] [Bulk] Re: Lucent/Symmetricom Z3810AS, KS24361 - They're Back
Dick, Getting them working is easy. Connect the supplied interface cable between the 'J5' connectors on each unit, supply an antenna connection to the TNC connector on the REF 1 unit, supply +24 VDC to pin 1 of P1 of both units, connect the 'return' to pin 2 of P1 of both units and stand back. As Bob says, there is a long list of posts about these units including how to communicate with them. The link on the listing is to a 'time-nuts' posting by Stewart Cobb and is very informative. Good luck. Joe -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard Solomon Sent: Thursday, May 21, 2015 3:36 PM To: Discussion of precise time and frequency measurement Subject: [Bulk] Re: [time-nuts] Lucent/Symmetricom Z3810AS, KS24361 - They're Back Is there a discussion somewhere on these units and how to get them working ? 73, Dick, W1KSZ On 5/20/2015 5:47 AM, J. L. Trantham wrote: Looks like another shipment for those that might have missed them before. Item 221777430088 No connection to seller except satisfied customer. Joe ___ time-nuts mailing 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] IRIG-B audio decoder circuits and ICs sought
Multiple answers interspersed below. Joe On Wed, 20 May 2015 10:04:19 -0400, time-nuts-requ...@febo.com wrote: Send time-nuts mailing list submissions to Message: 5 Date: Tue, 19 May 2015 22:08:47 +0200 From: Magnus Danielson mag...@rubidium.dyndns.org To: time-nuts@febo.com Cc: mag...@rubidium.se Subject: Re: [time-nuts] IRIG-B audio decoder circuits and ICs sought -- Joe, On 05/19/2015 03:51 PM, Joseph Gwinn wrote: I'm studying up on how IRIG-B decoder circuits work. What are the good approaches, the bad approaches, especially in the presence of noise? (I asked on the NTP group, with little result beyond the C/C++ decoder software written for the audio channel of a 1990s Sun workstation, which it ate alive: 50% cpu load.) Are there decoder ICs available? The closest to a decoder IC I've found is some FPGA code from a partner of Microsemi (nee Symmetricom): ..http://www.microsemi.com/products/fpga-soc/design-resources/partners/semquest All marketing and little technical information. I'll have to find out the details. I find very little, though I did find one intriguing idea using a Costas Loop to lock to the 1 KHz carrier, and a posting suggesting squaring the input signal and phase-locking to the 2 KHz result. Most recent articles on IRIG decoders come from Chinese sources, mostly in the AC power industry. There is a few different approaches for recovering the 1 kHz carrier. The AM modulation is naturally a bit of a challenge as it will modulate the slew-rate. Once the 100 Hz message is recovered, the break-down is relatively straight-forward. The question is really, what is the requirement you have and what type of processing do you think about. A corner of a FPGA will do it. The definition of good here is tenth-microsecond alignment between the 1PPS output of the decoder and the incoming IRIG-B12x signal. I prefer the DC level shifted variant of IRIG-B. I like and use IRIG-B00x too, but it only reaches a few meters, versus the required tens of meters. -- Message: 7 Date: Tue, 19 May 2015 16:37:58 -0400 From: Tim Shoppa tsho...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] IRIG-B audio decoder circuits and ICs sought See for example the Truetime 820 decoder. Discriminators, One-shots, and Flip-Flops with pots to tweak the levels. Hmm. Interesting. URL? Tim N3QE On Tuesday, May 19, 2015, Joseph Gwinn joegw...@comcast.net wrote: [snip] -- Message: 11 Date: Tue, 19 May 2015 23:59:13 +0300 From: Esa Heikkinen tn1...@nic.fi To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] IRIG-B audio decoder circuits and ICs sought Joseph Gwinn kirjoitti: I'm studying up on how IRIG-B decoder circuits work. What are the good approaches, the bad approaches, especially in the presence of noise? (I asked on the NTP group, with little result beyond the C/C++ decoder software written for the audio channel of a 1990s Sun workstation, which it ate alive: 50% cpu load.) I was also searching chips for IRIG-B decoding lately, but didn't find any. Then I decided to create my own, mostly just for fun but there's also some uses for it. So I ended up to use 8-bit PIC16F873 and do IRIG-B DCLS decoding with it. DCLS means logic level IRIG-B signal from Symmetricom TS2100. So it's not 1 kHz modulated. Yes, but I must have IRIG-B12x (Amplitude modulated 1 KHz sine wave), and the analog processing complicates things. I think that one best implements the IRIG decoder in a DSP chip. At a start it was only a time code decoder... Then, maybe because very rainy weather in the Finland, new features was added daily. For now, it calculates local time (calendar date and weekday) for IRIG-B day number and year and supports european daylight saving time. Leap second is also supported, if it's encoded in the IEEE1344 control bits (Tymserve TS2100 encodes this, leap seconds are flagged one minute before the actual leap second). IRIG-B timecode is also verified by checking its continuity. If there's momentary errors or total loss of timecode, timing continues in freerun mode. PPS is also generated from IRIG-B with about +-100 ns. maximum jitter (it's one instruction cycle of 'F873, so it cannot be done better with this MCU). If the whole system is rebooted due to long blackout with UPS batteries runout, TS2100 will jump back to January first of current year. And because TS2100 GPS functionality is now dead, it means that it will also continue with wrong time until it's manually set. Because of that, support for TS2100 resets was also added. Now it keeps record of passed dates on the EEPROM... :) TS2100s are generating a lot of replacement business for GPS vendors. Now I
Re: [time-nuts] IRIG-B audio decoder circuits and ICs sought
On Wed, 20 May 2015 12:00:01 -0400, time-nuts-requ...@febo.com wrote: Message: 1 Date: Wed, 20 May 2015 09:19:47 -0500 From: Graham / KE9H ke9h.gra...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] IRIG-B audio decoder circuits and ICs sought Message-ID: capyj-yu3fxv6i68gwqw1m1do3_tvry+oirv6r+uhhth3m48...@mail.gmail.com Content-Type: text/plain; charset=UTF-8 Be aware that there are about 100 variations on IRIG B, that is, B000 through B257. Yes. I wasn't being specific, but the signal is IRIG-B12x, most likely B124. You should obtain a copy of IRIG STANDARD 200-04, the 2004 version, which I believe is the most current. It is available on line, if you Google for it. Thanks, but already got it. Joe Gwinn End of time-nuts Digest, Vol 130, Issue 30 ** ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
