[time-nuts] PPS for NTP Server - How Close Is Good Enough?
Hi, this is my first post ever to a mailing list, so if I'm doing anything wrong please be gentle with your corrections :-) A short time ago I purchased a Nortel/Trimble NTGS50AA GPSTM, I'm sure many on this list are familiar with it. At the time of purchase, my only interest was the 10 MHz output, for use with my HP5328b frequency counter and perhaps in the future also my signal generator. No question here, it just works great as is. However, it certainly seems best to leave these devices powered up all the time. OK, now were getting close to my question. The unit pulls about 10-11 watts, which is really not very much. But it kinda bugs me to have it sit there using electric and basically doing nothing when I'm not using it. So, I bought a Raspberry Pi 2 with the intent of using it as an NTP server. I can't really say I'm enjoying my intro to Linux a whole lot, but I'll get there. It still needs some work, but it does function with the PPS output from an Adafruit ultimate GPS, which I bought for testing this and possibly building my own GPSDO in the future. The NTGS50AA is a very capable device, but unfortunately it does not have a PPS output. Instead it has an even second output, which goes low for approximately 50 ns. The falling edge of this pulse marks the beginning of the second. During my search for a solution to this, I came across a post from this mailing list which I believe was discussing repair of one of these units. Someone in that post mentioned that there was a PPS signal at test point 33 which went low for about 10 µs. Thank you, that saves me a lot of probing. The first thing I did was verify that this pulse did exist, then I decided to examine it a little closer. I kind of suspected that it may have been a rather raw pulse as received from the satellites. I found out that is not correct, once the unit successfully phase locks, this PPS signal is very accurately tied to the 10 MHz output, even when the unit goes into holdover mode. I was very happy about this :-) Next step was to see how accurately it was synced to the even second pulse. The bad news is that it does not occur at exactly the same time as the even second. The good news is that the offset is very consistent, 253 ns before the even second pulse, +/- 1 ns. My next step was to find out where the even second pulse entered the output circuitry. I then broke the trace taking the even second into the output circuitry, and ran a piece of 30gauge wire wrapping wire from the via at test point 33 to the via at the input to the output circuitry. The wire fit so perfectly it felt like the vias were made for just this purpose :-) Now I've got a very nice PPS signal available both at the front jack and at the backplane connector in the rear of the unit. OK, here is the actual question. Do you think it is OK to consider a pulse which arise 250 ns early to be close enough? And no, I am not forgetting about that 3 ns, there is about 3 ns of delay added by the output circuitry. Hope you didn't mind the long-winded post, and I thank you in advance for any advice you offer. Ed ___ time-nuts mailing 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] TymServe 2100 OCXO (MTI 240-0530-D)
Gerhard , Which firmware version are you running in the 2100? We never updated to the most recent due to the leap second thing. We do have the various firmware versions on disk. Andrew -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Gerhard Wittreich Sent: Saturday, June 06, 2015 4:57 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] TymServe 2100 OCXO (MTI 240-0530-D) I completed the TCXO to OCXO (MTI 240-0530-D) upgrade yesterday with no issues. TCXO is a bit troublesome to remove (Four through the hole mounts. Can made stiff and difficult to move any corner much. Slowly worked my way around the four mounts repeatedly until they came loose.) but a bit of patience goes a long way. You will need to de-solder the mounting holes for the OCXO but that went well. On restart I updated the two setting Jason Rabel indicated in his Mar 30 2011 post on [Time-Nuts]: OCXO (MTI 240-0530-D) - gain = -20 filter = 0.9995000 and then wrote that to eeprom using: eng eeprom gain -20 eng eeprom filter 0.9995 Make sure to short jumper JP4 on the board so the eeprom write will work. After restart the OCXO took about 3 hours to stabilize before Locked status was achieved. I did a cold restart (Power Off -- Power On did not wait for the OCXO to cool down) after 24 hours and got Locked status in less than 20 min. Now waiting on the new Trimble III clone from Heol to finish the upgrade. Gerhard R Wittreich, P.E. On Wed, Jun 3, 2015 at 3:49 PM, Andrew Cooper acoo...@keck.hawaii.edu wrote: Keep us updated on any progress (or pitfalls here). I just installed our new MicroSemi S350's a few minutes ago;) and pulled a couple TS2100's out of the rack. We would like to update these and have one of the Heol GPS units on order. Ours have OXCO's already, so it should just be the GPS. Andrew -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Gerhard Wittreich Sent: Wednesday, June 03, 2015 4:14 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] TymServe 2100 OCXO (MTI 240-0530-D) I'm giving the entire rebuild a try including the Ace Trimble III clone form Heol Design. I'm not sure it is practical but I like the idea of keeping an old unit running. I read the post you mentioned which does a nice job of discussing the firmware settings. I was hoping for some practical tips on removing and reinstalling the oscillators. Is it a straight forward desolder/resolder? Is there an insulating pad (thermal or electrical) under the OCXO? Any pitfalls? Gerhard R Wittreich, P.E. On Tue, Jun 2, 2015 at 10:41 PM, Robert Watzlavick roc...@watzlavick.com wrote: See the thread titled Upgrading TS2100 from TCXO to OCXO around 3/30/2011. I used a different OCXO but one that had a compatible EFC range. It's funny, a few weeks ago before the TS2100s started acting up, I would have picked up one of those OCXOs in a heartbeat. I've had an eBay watch set up for years waiting for that part. But now I'm not so sure I want it anymore. -Bob On 06/02/2015 08:32 AM, Gerhard Wittreich wrote: I just discovered that a correct model MTI OCXO (MTI 240-0530-D) for the TS-2100 is currently available on eBay. In the past MTI 240's of different versions have been available but unsuitable for the TS-2100. Price is $45.99 + shipping. I have one on the way. NEW Symmertricom BC11736-1000 MRI 240-0530-D 010285-0530-D Crystal Oscillator http://www.ebay.com/itm/NEW-Symmertricom-BC11736-1000-MRI-240-0530- D- 010285-0530-D-Crystal-Oscillator-/131510917585?pt=LH_DefaultDomain_ 0 hash=item1e9ea959d1 Now, has anyone replaced a stock oscillator with the correct MTI 240 in a TS-2100? Glad to take this off-line of the topic is not of general interest. Gerhard R. Wittreich, P.E. ___ time-nuts mailing 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
Re: [time-nuts] HP5370 Error 04
Hi Matthias - It sounds like you may have a temperature sensitive component (or solder joint?). Perhaps cooling each component individually will help you find the problem. Regards, John K1AE -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Matthias Jelen Sent: Tuesday, June 09, 2015 2:31 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] HP5370 Error 04 Hello John, thanks for that information. Unfortunately, my fan is working. Opening the lid and putting an extra blower to cool the VCO helps to extend the time until he error occurs... Regards, Matthias Hello Matthias - I had this problem on my 5370B - it turned out that the fan wasn't running, which resulted in overheating. I hope this helps. Regards, John K1AE -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Matthias Jelen Sent: Monday, June 08, 2015 9:28 AM To: time-nuts@febo.com; dk...@gmx.de Subject: [time-nuts] HP5370 Error 04 Hello! I´ve got a question to the 5370 experts on the list. I just received my new (old...) HP5370a. It performed fine for abt. one hour, then it started to display error 04 which means PLL out of lock. A look in the service manual revealed that there are several reasons for this. I checked the VCO voltage on both interpolator cards, and indeed, one of them is out of the specified -6V..-3V, it runs to the rail (-12V). Even if the error is not there, the voltage is at abt. -7 V, so I guess it´s just on the edge. The other card is fine. Normally, I´d try the alignment procedure, but I´m missing the exotic HP pulse generator used for the alignment and I have no clue how I could easily substitute this one. Did anyone encounter this problem before? Is there a cure for this problem known to the experts? Any hints are highly appreciated... Thanks a lot, Matthias, DK4YJ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ___ time-nuts mailing 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. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ___ time-nuts mailing 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] PPS for NTP Server - How Close Is Good Enough?
Do you think it is OK to consider a pulse which arise 250 ns early to be close enough? For NTP usage that will be no problem whatsoever. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PPS for NTP Server - How Close Is Good Enough?
On Wed, Jun 10, 2015 at 6:30 AM, Ed Armstrong eds_equipm...@verizon.net wrote: Hi, this is my first post ever to a mailing list, so if I'm doing anything wrong please be gentle with your corrections :-) Welcome! [snip] My next step was to find out where the even second pulse entered the output circuitry. I then broke the trace taking the even second into the output circuitry, and ran a piece of 30gauge wire wrapping wire from the via at test point 33 to the via at the input to the output circuitry. The wire fit so perfectly it felt like the vias were made for just this purpose :-) Now I've got a very nice PPS signal available both at the front jack and at the backplane connector in the rear of the unit. Very clever. OK, here is the actual question. Do you think it is OK to consider a pulse which arise 250 ns early to be close enough? And no, I am not forgetting about that 3 ns, there is about 3 ns of delay added by the output circuitry. Depends on your needs, of course. For NTP, 250ns will be essentially unnoticeable. For other purposes, it might be an issue, but not for NTP. NTP typically works on the micro- and millisecond level. Any offset or jitter on the nanosecond level will be lost in the noise, so to speak: the interrupt latency of the Pi will far exceed any nanosecond-level offset. Cheers! -Pete -- Pete Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PPS for NTP Server - How Close Is Good Enough?
From: Ed Armstrong [] OK, here is the actual question. Do you think it is OK to consider a pulse which arise 250 ns early to be close enough? And no, I am not forgetting about that 3 ns, there is about 3 ns of delay added by the output circuitry. Hope you didn't mind the long-winded post, and I thank you in advance for any advice you offer. Ed ___ Yes, Ed, if you are within a microsecond for the PPS input to your Raspberry Pi that's fine. Don't forget it's a 3.3 V level. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PPS for NTP Server - How Close Is Good Enough?
For driving NTP.. 1) NTP works in microseconds and your networked clients will see accuracy in the range of a few milliseconds. 2) There is a way to fix this in NTP's configuration file, you can specify what the delay is. On Tue, Jun 9, 2015 at 9:30 PM, Ed Armstrong eds_equipm...@verizon.net wrote: Hi, this is my first post ever to a mailing list, so if I'm doing anything wrong please be gentle with your corrections :-) A short time ago I purchased a Nortel/Trimble NTGS50AA GPSTM, I'm sure many on this list are familiar with it. At the time of purchase, my only interest was the 10 MHz output, for use with my HP5328b frequency counter and perhaps in the future also my signal generator. No question here, it just works great as is. However, it certainly seems best to leave these devices powered up all the time. OK, now were getting close to my question. The unit pulls about 10-11 watts, which is really not very much. But it kinda bugs me to have it sit there using electric and basically doing nothing when I'm not using it. So, I bought a Raspberry Pi 2 with the intent of using it as an NTP server. I can't really say I'm enjoying my intro to Linux a whole lot, but I'll get there. It still needs some work, but it does function with the PPS output from an Adafruit ultimate GPS, which I bought for testing this and possibly building my own GPSDO in the future. The NTGS50AA is a very capable device, but unfortunately it does not have a PPS output. Instead it has an even second output, which goes low for approximately 50 ns. The falling edge of this pulse marks the beginning of the second. During my search for a solution to this, I came across a post from this mailing list which I believe was discussing repair of one of these units. Someone in that post mentioned that there was a PPS signal at test point 33 which went low for about 10 µs. Thank you, that saves me a lot of probing. The first thing I did was verify that this pulse did exist, then I decided to examine it a little closer. I kind of suspected that it may have been a rather raw pulse as received from the satellites. I found out that is not correct, once the unit successfully phase locks, this PPS signal is very accurately tied to the 10 MHz output, even when the unit goes into holdover mode. I was very happy about this :-) Next step was to see how accurately it was synced to the even second pulse. The bad news is that it does not occur at exactly the same time as the even second. The good news is that the offset is very consistent, 253 ns before the even second pulse, +/- 1 ns. My next step was to find out where the even second pulse entered the output circuitry. I then broke the trace taking the even second into the output circuitry, and ran a piece of 30gauge wire wrapping wire from the via at test point 33 to the via at the input to the output circuitry. The wire fit so perfectly it felt like the vias were made for just this purpose :-) Now I've got a very nice PPS signal available both at the front jack and at the backplane connector in the rear of the unit. OK, here is the actual question. Do you think it is OK to consider a pulse which arise 250 ns early to be close enough? And no, I am not forgetting about that 3 ns, there is about 3 ns of delay added by the output circuitry. Hope you didn't mind the long-winded post, and I thank you in advance for any advice you offer. Ed ___ time-nuts mailing 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] Performance of 74LVC series ICs
Thanks for all of the replies, very useful. Also for the recommendations on the 74LVC1G74 and 1G80. I don't know why I didn't check for a 7474 in this technology, of course they would have that available. But it looks like the 1G80 will do just exactly what I need in a smaller package, so I think I'll go with that. Dan On Tue, Jun 9, 2015 at 8:52 AM, Dan Kemppainen d...@irtelemetrics.com wrote: Hi Dan, 74LVC1G80. See: http://www.ti.com/lit/ds/symlink/sn74lvc1g80.pdf Might be worth looking at. Dan On 6/9/2015 4:24 AM, time-nuts-requ...@febo.com wrote: Let's say I have a 20MHz TCXO. I want to square up the output signal and divide by two. Easy, just a buffer or inverter and a flip flop. But looking at the pinout of the 74LVC1G175 (D flip flop) it doesn't have a Q not output. So now I need a second inverter to make it toggle. The 74LVC2G14 includes two schmitt inverters in the package, but will isolation inside the device be good enough to use it for two separate functions at 20 and 10 MHz? ___ time-nuts mailing 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] z3801a - serial help and for sale.
I'm throwing my hands up in the air - I don't have the time to wrestle my silly mac into trying to talk to the box, unless someone has quick advice on something I might be doing wrong. z3801a, jumpered to RS232, modified with an internal switching power supply (see photos below). Power light comes on, unit is outputting stable 10MHz. Doesn't GPS lock, but that makes sense, since I haven't been able to issue a SURVEY command and I don't live where I used to. The internal green status light is blinking (as normal), suggesting that it's probably happy and I'm an idiot for not being able to make it work, but I don't vouch for anything about it past the 10mhz being there. The double-oven oscillator is clearly happy given the 10mhz (compared against a working Thunderbolt). Hooked up a serial cable at 19200, 7, O, 1, but only got a garbled little prompt back - no response to standard z3801a commands. I *think* I have the cable configured properly. I opened it up and checked the RS232 jumpers and they're correct. I'm open to advice on getting the serial working under my Mac or Linux, or anyone who wants to relieve me of the burden of z3801a ownership and take a risk that it's a fixer-upper. :-) I suspect that in some previous life, I switched it over into a binary mode of some sort while using it to sync something, but I can't for the life of me remember what I might have done. Some reasonable price plus shipping and it's all yours... I'm trying to de-clutter in preparation for a sabbatical on the other side of the country. Pictures: https://www.dropbox.com/s/ursszjgie8m1xj8/2015-06-09%2011.57.16.jpg?dl=0 https://www.dropbox.com/s/it8d2f65ztn4rkq/2015-06-09%2011.57.24.jpg?dl=0 https://www.dropbox.com/s/1p1g6xrapzdmvzh/2015-06-09%2011.59.56.jpg?dl=0 Thanks! -Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PPS for NTP Server - How Close Is Good Enough?
Hi Ed -- For standard PC hardware, 250ns is way under the interrupt granularity of the computer, and will never be noticed. Some specialized configurations (https://www.febo.com/pages/soekris/) have timer resolution to a few hundred nanoseconds, but that takes hacking. I know there have been discussions about the RPi as an ntp server, and I don't recall anyone talking about what a wizard device is was as a pure timekeeper. It ultimately comes down to the interrupt resolution, and the short-term stability of the computer clock source. So, (a) I don't think you don't need to worry, and (b) even if you do, you can insert a fudge factor into the ntp configuration to neutralize fixed offsets like this. John On 6/10/2015 12:30 AM, Ed Armstrong wrote: Hi, this is my first post ever to a mailing list, so if I'm doing anything wrong please be gentle with your corrections :-) A short time ago I purchased a Nortel/Trimble NTGS50AA GPSTM, I'm sure many on this list are familiar with it. At the time of purchase, my only interest was the 10 MHz output, for use with my HP5328b frequency counter and perhaps in the future also my signal generator. No question here, it just works great as is. However, it certainly seems best to leave these devices powered up all the time. OK, now were getting close to my question. The unit pulls about 10-11 watts, which is really not very much. But it kinda bugs me to have it sit there using electric and basically doing nothing when I'm not using it. So, I bought a Raspberry Pi 2 with the intent of using it as an NTP server. I can't really say I'm enjoying my intro to Linux a whole lot, but I'll get there. It still needs some work, but it does function with the PPS output from an Adafruit ultimate GPS, which I bought for testing this and possibly building my own GPSDO in the future. The NTGS50AA is a very capable device, but unfortunately it does not have a PPS output. Instead it has an even second output, which goes low for approximately 50 ns. The falling edge of this pulse marks the beginning of the second. During my search for a solution to this, I came across a post from this mailing list which I believe was discussing repair of one of these units. Someone in that post mentioned that there was a PPS signal at test point 33 which went low for about 10 µs. Thank you, that saves me a lot of probing. The first thing I did was verify that this pulse did exist, then I decided to examine it a little closer. I kind of suspected that it may have been a rather raw pulse as received from the satellites. I found out that is not correct, once the unit successfully phase locks, this PPS signal is very accurately tied to the 10 MHz output, even when the unit goes into holdover mode. I was very happy about this :-) Next step was to see how accurately it was synced to the even second pulse. The bad news is that it does not occur at exactly the same time as the even second. The good news is that the offset is very consistent, 253 ns before the even second pulse, +/- 1 ns. My next step was to find out where the even second pulse entered the output circuitry. I then broke the trace taking the even second into the output circuitry, and ran a piece of 30gauge wire wrapping wire from the via at test point 33 to the via at the input to the output circuitry. The wire fit so perfectly it felt like the vias were made for just this purpose :-) Now I've got a very nice PPS signal available both at the front jack and at the backplane connector in the rear of the unit. OK, here is the actual question. Do you think it is OK to consider a pulse which arise 250 ns early to be close enough? And no, I am not forgetting about that 3 ns, there is about 3 ns of delay added by the output circuitry. Hope you didn't mind the long-winded post, and I thank you in advance for any advice you offer. Ed ___ time-nuts mailing 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] NTG550AA 1 PPS mod
Hi Ed, I am the one who discovered the 1PPS pulse while troubleshooting a NTG550AA. Instead of reuse the 1/2 PPS output and missing this signal, my plan is to recycle the 9.8304 MHz output circuitry and connector, the circuits are almost identical. So I will cut the trace that goes from TP14 to U405 pin 6 and also use a wire wrapping wire to joint TP14 to TP33 so the 1PPS will be at J5. I think that I will do the modification this weekend. I don't imagine any future use of the X8 Chip signal but having the even second output could be useful, at least to see the difference with the 1 PPS. I had not measured the time difference yet, but I made a partial schematic of the board for my troubleshooting and there I see that the 1/2 PPS signal is synchronized with the 19.6608 signal that is the source for the 8X Chip ( 9.8304 MHz), this is done in U405B . The period of this signal is about 50 ns and this is the origin of the 1/2 PPS width. The 19.6608 MHz oscillator is phase locked somewhere to the 10 MHz oscillator thus it is as stable as this one. I think that using the other half of U405, which actually is used to divide by 2 the 19.6608 MHz signal, could render the 1 PPS synchronized with the 1/2 PPS and also with the same width. Probably the easier way to correct this is to use the command which sets the antenna cable delay and compensate for the difference. I don't have a full schematic, even I am not sure that the partial one is 100% correct but I can send it to anyone who wants it. Regards, Ignacio El 10/06/2015 a las 6:30, Ed Armstrong wrote: Hi, this is my first post ever to a mailing list, so if I'm doing anything wrong please be gentle with your corrections :-) A short time ago I purchased a Nortel/Trimble NTGS50AA GPSTM, I'm sure many on this list are familiar with it. At the time of purchase, my only interest was the 10 MHz output, for use with my HP5328b frequency counter and perhaps in the future also my signal generator. No question here, it just works great as is. However, it certainly seems best to leave these devices powered up all the time. OK, now were getting close to my question. The unit pulls about 10-11 watts, which is really not very much. But it kinda bugs me to have it sit there using electric and basically doing nothing when I'm not using it. So, I bought a Raspberry Pi 2 with the intent of using it as an NTP server. I can't really say I'm enjoying my intro to Linux a whole lot, but I'll get there. It still needs some work, but it does function with the PPS output from an Adafruit ultimate GPS, which I bought for testing this and possibly building my own GPSDO in the future. The NTGS50AA is a very capable device, but unfortunately it does not have a PPS output. Instead it has an even second output, which goes low for approximately 50 ns. The falling edge of this pulse marks the beginning of the second. During my search for a solution to this, I came across a post from this mailing list which I believe was discussing repair of one of these units. Someone in that post mentioned that there was a PPS signal at test point 33 which went low for about 10 µs. Thank you, that saves me a lot of probing. The first thing I did was verify that this pulse did exist, then I decided to examine it a little closer. I kind of suspected that it may have been a rather raw pulse as received from the satellites. I found out that is not correct, once the unit successfully phase locks, this PPS signal is very accurately tied to the 10 MHz output, even when the unit goes into holdover mode. I was very happy about this :-) Next step was to see how accurately it was synced to the even second pulse. The bad news is that it does not occur at exactly the same time as the even second. The good news is that the offset is very consistent, 253 ns before the even second pulse, +/- 1 ns. My next step was to find out where the even second pulse entered the output circuitry. I then broke the trace taking the even second into the output circuitry, and ran a piece of 30gauge wire wrapping wire from the via at test point 33 to the via at the input to the output circuitry. The wire fit so perfectly it felt like the vias were made for just this purpose :-) Now I've got a very nice PPS signal available both at the front jack and at the backplane connector in the rear of the unit. OK, here is the actual question. Do you think it is OK to consider a pulse which arise 250 ns early to be close enough? And no, I am not forgetting about that 3 ns, there is about 3 ns of delay added by the output circuitry. Hope you didn't mind the long-winded post, and I thank you in advance for any advice you offer. Ed ___ time-nuts mailing 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] PPS for NTP Server - How Close Is Good Enough?
Ed, first of all, welcome to the mail list! I have been lurking here for some time now and wanted to try an apply what I have learned about NTP to your question. I, too, haven't posted on here before, so please forgive me if I have quoted his question wrong, and replied incorrectly. I believe that as long as the pulse is consistent , the fact that it is 'early' should make little to no difference. To give an example from my experimentation with using GPS receivers and independent rubidium oscillators for the PPS input into NTP, I found the following to be true: 1) that a PPS signal alone (without any NMEA strings from the GPS receiver) requires a 'prefer' peer configured in the ntp.conf file (as is stated in the refclock driver docs) to number the seconds - or in other words - to give NTP an idea exactly what second that it is seeing from the PPS source. I have taken to calling these epoch seconds or numbered seconds. 2) that a PPS signal from an oscillator (one which ticks seconds, but not necessarily the second, or epoch seconds) is going to be pretty accurate and give a good timing source but its second is going to be offset from the true or epoch second based upon when you powered it on. Since it's not locked to any true source, and is simply going to give you a very accurate pulse every second on its own schedule, I have taken to calling these orphan seconds. 3) when NTP sees a PPS source from GPS (again, no NMEA strings, just the PPS signal), it checks with its 'prefer' peer and sees the numbered second, the true second, and is pretty happy with the GPS PPS source. (that is, assuming, it's 'prefer' peer is using GPS or the like to number ITS seconds) When NTP sees a PPS source from an oscillator, since the same driver is being used, it also checks with its 'prefer' peer, sees the numbered second, and is NOT at all happy with the PPS source (and will de-select it and mark it as a falseticker) since it is offset by some random amount from the true second. It may be giving a PPS, but they are orphan seconds. 4) I have found that the solution to orphan seconds using the PPS Clock Discipline driver listed here: http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver22.html is to adjust the time1 fudge factor to an offset that matches how far off the oscillator orphan seconds are from - say - a GPS sourced epoch second. This offset should be entered in SECONDS on the fudge line for that driver. 5) to be very clear, let me draw a picture here. Below, J is a PPS from a GPS source (epoch seconds) and K is a PPS from an oscillator (orphan seconds). They are 242ms apart in the diagram: ...K...242ms...J...758ms...K...242ms...J...758ms...K...242ms... I would then set the time1 fudge factor for this driver to -0.242 (or, I guess 0.758) 6) I was told that (with a similar driver, the NMEA driver here: http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html ) as long as the PPS is within 500ms that NTP can correlate the two. I haven't found that to be true with the PPS Clock Discipline driver. 7) this fudge factor is going to drift over time, since that independent oscillator isn't being disciplined from a source of epoch seconds. How much it will drift and when depend on the oscillator. 8) I would say that close enough really depends upon your application. These orphan seconds could also come from - say - a 10MHz source that has been divided down to 1Hz (or a PPS). That, too, is going to give you very accurate seconds, but not necessarily THE second since it is going to change depending when you turned it on. I think that with the correct fudge factor and your source, that you will find a very nice, accurate, fudged clock for inputting the PPS into your Raspberry Pi. (something I, too am experimenting with and have several Pi set up and running NTP). Cheers! -Randal r3 -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Ed Armstrong Sent: Tuesday, 09 June, 2015 22:30 To: Discussion of precise time and frequency measurement Subject: [time-nuts] PPS for NTP Server - How Close Is Good Enough? Hi, this is my first post ever to a mailing list, so if I'm doing anything wrong please be gentle with your corrections :-) A short time ago I purchased a Nortel/Trimble NTGS50AA GPSTM, I'm sure many on this list are familiar with it. At the time of purchase, my only interest was the 10 MHz output, for use with my HP5328b frequency counter and perhaps in the future also my signal generator. No question here, it just works great as is. However, it certainly seems best to leave these devices powered up all the time. OK, now were getting close to my question. The unit pulls about 10-11 watts, which is really not very much. But it kinda bugs me to have it sit there using electric and basically doing nothing when I'm not using it. So, I bought a Raspberry Pi 2 with the intent of using it as
Re: [time-nuts] PPS for NTP Server - How Close Is Good Enough?
On Wed, Jun 10, 2015 at 12:30 PM, Ed Armstrong eds_equipm...@verizon.net wrote: OK, here is the actual question. Do you think it is OK to consider a pulse which arise 250 ns early to be close enough? And no, I am not forgetting about that 3 ns, there is about 3 ns of delay added by the output circuitry. If you know what the offset is, and it is stable, (and you have shown you understand PCB traces, etc), I do not see how this is not OK. For someone like me, who cannot solder, and wants something off-the-shelf, it would be a problem. I would not know how to correct for the offset. If you are feeding this to NTP, the driver has a fuge factor, which you can use to consistently compensate for the 240ns (although I doubt the Pi is stable to that level). -- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane ___ time-nuts mailing 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] PPS for NTP Server - How Close Is Good Enough?
Hi Welcome! At best your NTP setup will be good to a few microseconds. By the time you get the time delivered (even over a LAN) it will be good to a few hundred microseconds at best. The ~ 250 ns error should not be a big deal. This being Time Nuts, you might take a look at the options on NTP and the drivers. I believe you will find an “offset” capability buried down in there. It’s most commonly used for radio (WWVB etc) based clocks. (They need to be corrected for propagation). Based on observing it’s use on public servers - it’s pretty easy to get the setting backwards. Of course it does beg the question of “which pulse is correct?”. Without further research, (and more timing gear :) there’s no real way to be sure that the even pps is right …. Bob On Jun 10, 2015, at 12:30 AM, Ed Armstrong eds_equipm...@verizon.net wrote: Hi, this is my first post ever to a mailing list, so if I'm doing anything wrong please be gentle with your corrections :-) A short time ago I purchased a Nortel/Trimble NTGS50AA GPSTM, I'm sure many on this list are familiar with it. At the time of purchase, my only interest was the 10 MHz output, for use with my HP5328b frequency counter and perhaps in the future also my signal generator. No question here, it just works great as is. However, it certainly seems best to leave these devices powered up all the time. OK, now were getting close to my question. The unit pulls about 10-11 watts, which is really not very much. But it kinda bugs me to have it sit there using electric and basically doing nothing when I'm not using it. So, I bought a Raspberry Pi 2 with the intent of using it as an NTP server. I can't really say I'm enjoying my intro to Linux a whole lot, but I'll get there. It still needs some work, but it does function with the PPS output from an Adafruit ultimate GPS, which I bought for testing this and possibly building my own GPSDO in the future. The NTGS50AA is a very capable device, but unfortunately it does not have a PPS output. Instead it has an even second output, which goes low for approximately 50 ns. The falling edge of this pulse marks the beginning of the second. During my search for a solution to this, I came across a post from this mailing list which I believe was discussing repair of one of these units. Someone in that post mentioned that there was a PPS signal at test point 33 which went low for about 10 µs. Thank you, that saves me a lot of probing. The first thing I did was verify that this pulse did exist, then I decided to examine it a little closer. I kind of suspected that it may have been a rather raw pulse as received from the satellites. I found out that is not correct, once the unit successfully phase locks, this PPS signal is very accurately tied to the 10 MHz output, even when the unit goes into holdover mode. I was very happy about this :-) Next step was to see how accurately it was synced to the even second pulse. The bad news is that it does not occur at exactly the same time as the even second. The good news is that the offset is very consistent, 253 ns before the even second pulse, +/- 1 ns. My next step was to find out where the even second pulse entered the output circuitry. I then broke the trace taking the even second into the output circuitry, and ran a piece of 30gauge wire wrapping wire from the via at test point 33 to the via at the input to the output circuitry. The wire fit so perfectly it felt like the vias were made for just this purpose :-) Now I've got a very nice PPS signal available both at the front jack and at the backplane connector in the rear of the unit. OK, here is the actual question. Do you think it is OK to consider a pulse which arise 250 ns early to be close enough? And no, I am not forgetting about that 3 ns, there is about 3 ns of delay added by the output circuitry. Hope you didn't mind the long-winded post, and I thank you in advance for any advice you offer. Ed ___ time-nuts mailing 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] Using CPLD/FPGA or similar for frequency
alan.ambr...@anagram.net said: How about a 1pS resolution TIC? :) An alternative way to describe that sort of problem is How accurately can you locate an edge? I haven't looked carefully at the Spartan 3E. You might be able to run a signal along a column through a slow path and clock the whole column at the same time. Then sort out how far it got. That slow path is basically a delay line with many taps. It would take some experimentation, and maybe some duplicate logic for run time calibration. Or a 12 digit frequency counter? :) :) 12 digits is easy. Just wait long enough. So that turns into 2 games: How fast can you count? How many digits can you get in 1 second? Here is a toy that would be useful: assume you have a 10 MHz reference clock. make a design that captures something like a PPS and spits out the time-stamp on a serial port. I think Tom has a PIC that does that. The idea here is to use a faster clock so you get better resolution. How much resolution can you get with pure digital logic? (no delay lines) I'd like something like that watching the power line. You might need some sort of compression scheme or the serial port would get overloaded. 9600 baud is 1K characters per second. 60 Hz is 16 ms per cycle so you get 15 characters per cycle (plus a separator) unless there is noise on the line. 9 digits gives you ns. within the second. Every second or so you could send the high-order digits. -- 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] MTI-240-0530-D
Sorry, this sheet has the last page with pin-outs. http://www.ko4bb.com/manuals/50.158.136.69/MTI-240-0530-D.pdf greg On Jun 10, 2015, at 11:55 AM, Gregory Beat w...@icloud.com wrote: Did someone ask about the MTI-240-0530-D Oscillator Specification? AT crystal cut, found on this spec sheet on Internet http://www.prostudioconnection.net/1312/MTI-240-0530-D.pdf greg w9gb Sent from iPad Air ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PPS for NTP Server - How Close Is Good Enough?
On Tue, June 9, 2015 11:30 pm, Ed Armstrong wrote: OK, here is the actual question. Do you think it is OK to consider a pulse which arise 250 ns early to be close enough? It is only 250ns early relative to the even second output. What is the even second output referenced to? What most people care about is relation to established UTC, and that you don't know for either pulse. You did not mention measuring the length of the antenna cable and adjusting for that. That will probably be a few tens of nanoseconds. There could be other processing delays or propagation delays in the signal path. Without accounting for all of those, and knowing whether the firmware in the GPSDO takes those into account, you don't really know whether the PPS is early, or the PP2S is late relative to UTC (and assuming you have accounted for antenna delay). -- Chris Caudle ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] z3801a - serial help and for sale.
Try going through all the speeds starting at 300. Sounds like a baud rate mismatch to me from the symptoms Also try 8 bits 1 stop no parity Content by Scott Typos by Siri On Jun 10, 2015, at 10:28 AM, David Andersen d...@pobox.com wrote: I'm throwing my hands up in the air - I don't have the time to wrestle my silly mac into trying to talk to the box, unless someone has quick advice on something I might be doing wrong. z3801a, jumpered to RS232, modified with an internal switching power supply (see photos below). Power light comes on, unit is outputting stable 10MHz. Doesn't GPS lock, but that makes sense, since I haven't been able to issue a SURVEY command and I don't live where I used to. The internal green status light is blinking (as normal), suggesting that it's probably happy and I'm an idiot for not being able to make it work, but I don't vouch for anything about it past the 10mhz being there. The double-oven oscillator is clearly happy given the 10mhz (compared against a working Thunderbolt). Hooked up a serial cable at 19200, 7, O, 1, but only got a garbled little prompt back - no response to standard z3801a commands. I *think* I have the cable configured properly. I opened it up and checked the RS232 jumpers and they're correct. I'm open to advice on getting the serial working under my Mac or Linux, or anyone who wants to relieve me of the burden of z3801a ownership and take a risk that it's a fixer-upper. :-) I suspect that in some previous life, I switched it over into a binary mode of some sort while using it to sync something, but I can't for the life of me remember what I might have done. Some reasonable price plus shipping and it's all yours... I'm trying to de-clutter in preparation for a sabbatical on the other side of the country. Pictures: https://www.dropbox.com/s/ursszjgie8m1xj8/2015-06-09%2011.57.16.jpg?dl=0 https://www.dropbox.com/s/it8d2f65ztn4rkq/2015-06-09%2011.57.24.jpg?dl=0 https://www.dropbox.com/s/1p1g6xrapzdmvzh/2015-06-09%2011.59.56.jpg?dl=0 Thanks! -Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] z3801a - serial help and for sale.
Hi Normal drill for this sort of thing: 1) First connect the serial dongle back to back (output to input) and make sure it gives you back what you type in. If not, find another dongle. 2) Check the output levels from the Z3801 with a scope. It should be swinging at least +/- 5V and more like +/-12. The key thing here is that the swing is the same in both directions. Then, in combination, try each of the following: 3) Try the usual suspects in terms of parity: 8N1, 7E1, 7O1 4) Try the usual speeds: 4800, 9600, 19200 A quick power cycle between each of the 9 possibilities should get it feeding out something that you can recognize. Yes this is a generic approach, but sometimes the generic one is quicker than doing a bunch of research, looking for notes on how you switched the thing around back months ago …. Bob On Jun 10, 2015, at 10:28 AM, David Andersen d...@pobox.com wrote: I'm throwing my hands up in the air - I don't have the time to wrestle my silly mac into trying to talk to the box, unless someone has quick advice on something I might be doing wrong. z3801a, jumpered to RS232, modified with an internal switching power supply (see photos below). Power light comes on, unit is outputting stable 10MHz. Doesn't GPS lock, but that makes sense, since I haven't been able to issue a SURVEY command and I don't live where I used to. The internal green status light is blinking (as normal), suggesting that it's probably happy and I'm an idiot for not being able to make it work, but I don't vouch for anything about it past the 10mhz being there. The double-oven oscillator is clearly happy given the 10mhz (compared against a working Thunderbolt). Hooked up a serial cable at 19200, 7, O, 1, but only got a garbled little prompt back - no response to standard z3801a commands. I *think* I have the cable configured properly. I opened it up and checked the RS232 jumpers and they're correct. I'm open to advice on getting the serial working under my Mac or Linux, or anyone who wants to relieve me of the burden of z3801a ownership and take a risk that it's a fixer-upper. :-) I suspect that in some previous life, I switched it over into a binary mode of some sort while using it to sync something, but I can't for the life of me remember what I might have done. Some reasonable price plus shipping and it's all yours... I'm trying to de-clutter in preparation for a sabbatical on the other side of the country. Pictures: https://www.dropbox.com/s/ursszjgie8m1xj8/2015-06-09%2011.57.16.jpg?dl=0 https://www.dropbox.com/s/it8d2f65ztn4rkq/2015-06-09%2011.57.24.jpg?dl=0 https://www.dropbox.com/s/1p1g6xrapzdmvzh/2015-06-09%2011.59.56.jpg?dl=0 Thanks! -Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] z3801a - serial help and for sale.
David, Using a USB dongle with an Apple Mac Laptop works fine for me. The chip is a FTDI FT232BL. Drivers from the FTDI site. In terminal or console use one of the following commands: [generic $5 dongle with no serial number] cd /dev screen tty.usbserial [xs880 with a serial number, http://www.usconverters.com/usb-serial-adapter-xs880] cd /dev screen tty.usbserial-A101OFXZ Having one (or more) with a serial number(s) allows several to work at the same time... I use the same USB-serial converters on windows PCs too. Jim - Original Message - From: David Andersen d...@pobox.com To: time-nuts@febo.com Sent: Wednesday, June 10, 2015 10:28:30 AM Subject: [time-nuts] z3801a - serial help and for sale. I'm throwing my hands up in the air - I don't have the time to wrestle my silly mac into trying to talk to the box, unless someone has quick advice on something I might be doing wrong. z3801a, jumpered to RS232, modified with an internal switching power supply (see photos below). Power light comes on, unit is outputting stable 10MHz. Doesn't GPS lock, but that makes sense, since I haven't been able to issue a SURVEY command and I don't live where I used to. The internal green status light is blinking (as normal), suggesting that it's probably happy and I'm an idiot for not being able to make it work, but I don't vouch for anything about it past the 10mhz being there. The double-oven oscillator is clearly happy given the 10mhz (compared against a working Thunderbolt). Hooked up a serial cable at 19200, 7, O, 1, but only got a garbled little prompt back - no response to standard z3801a commands. I *think* I have the cable configured properly. I opened it up and checked the RS232 jumpers and they're correct. I'm open to advice on getting the serial working under my Mac or Linux, or anyone who wants to relieve me of the burden of z3801a ownership and take a risk that it's a fixer-upper. :-) I suspect that in some previous life, I switched it over into a binary mode of some sort while using it to sync something, but I can't for the life of me remember what I might have done. Some reasonable price plus shipping and it's all yours... I'm trying to de-clutter in preparation for a sabbatical on the other side of the country. Pictures: https://www.dropbox.com/s/ursszjgie8m1xj8/2015-06-09%2011.57.16.jpg?dl=0 https://www.dropbox.com/s/it8d2f65ztn4rkq/2015-06-09%2011.57.24.jpg?dl=0 https://www.dropbox.com/s/1p1g6xrapzdmvzh/2015-06-09%2011.59.56.jpg?dl=0 Thanks! -Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Symmetricom SGC1500 Smart Grid Clock- Not Booting
Hello! Does anyone have firmware for one of these? I have one that is stuck on the loading OS screen. Perhaps I need clones of either the CF card or Micro SD card socketed inside the unit. Perhaps any experience with this symptom? They made one with a Rb, but I don't see where it would fit in here- or what model it could have been. Any info would be nice. Thanks- David ___ time-nuts mailing 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] PPS for NTP Server - How Close Is Good Enough?
eds_equipm...@verizon.net said: OK, here is the actual question. Do you think it is OK to consider a pulse which arise 250 ns early to be close enough? And no, I am not forgetting about that 3 ns, there is about 3 ns of delay added by the output circuitry. If you want to earn your time-nut merit badge, you have to measure it. The Ethernet on the Raspberry Pi is on the USB bus. That adds about a 1/2 ms of jitter. If you are using ntpd, there is a fudge factor that lets you correct for any offset. (and another one that lets you use the other edge, but I think the Pi doesn't capture it) -- 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] Using CPLD/FPGA or similar for frequency
HI On Jun 10, 2015, at 3:28 AM, Hal Murray hmur...@megapathdsl.net wrote: alan.ambr...@anagram.net said: How about a 1pS resolution TIC? :) An alternative way to describe that sort of problem is How accurately can you locate an edge? I haven't looked carefully at the Spartan 3E. You might be able to run a signal along a column through a slow path and clock the whole column at the same time. Then sort out how far it got. That slow path is basically a delay line with many taps. The delay line in an FPGA approach might get you to 20 ps. There is a lot of hand waving in the calibration process to get there. ( = figuring out that state A came before state B is based on things that are difficult to prove). If you do get it calibrated, you then find that it’s sensitive to both supply voltage and to temperature. The supply thing you can take care of with a good regulator. The “shifts all over the place when you put your thumb on it” T/C is not quite as easy to deal with. A TDC using an R/C and an ADC is a *much* easier way to go. It would take some experimentation, and maybe some duplicate logic for run time calibration. Or a 12 digit frequency counter? :) :) 12 digits is easy. Just wait long enough. So that turns into 2 games: How fast can you count? How many digits can you get in 1 second? Here is a toy that would be useful: assume you have a 10 MHz reference clock. make a design that captures something like a PPS and spits out the time-stamp on a serial port. I think Tom has a PIC that does that. The idea here is to use a faster clock so you get better resolution. How much resolution can you get with pure digital logic? (no delay lines) It depends on how much money you want to pay for your FPGA :) If you get one that will do both edges of a 600 MHz clock and run two phases, you can get to around 1/2 ns. Can you *believe* that 1/2 ns? well ….. Do you want to spend more money on a chip than a 500 ps counter would cost at auction …. Bob I'd like something like that watching the power line. You might need some sort of compression scheme or the serial port would get overloaded. 9600 baud is 1K characters per second. 60 Hz is 16 ms per cycle so you get 15 characters per cycle (plus a separator) unless there is noise on the line. 9 digits gives you ns. within the second. Every second or so you could send the high-order digits. -- 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] z3801a - serial help and for sale.
kb...@n1k.org said: 2) Check the output levels from the Z3801 with a scope. ... A quick power cycle between each of the 9 possibilities should get it feeding out something that you can recognize. Yes this is a generic approach, but sometimes the generic one is quicker than doing a bunch of research, looking for notes on how you switched the thing around back months ago â¦. If you have the scope out, you can easily check the baud rate and with a bit more work you can probably get the parity. -- 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] More Wenzel Oscillators
Both Wenzel 500-07078 oscillators have been paid for and shipped. Thank you time-nuts members. Ivan Cousins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
