Re: [time-nuts] optically excite a quartz crystal?
I'll have to check (dig it out from under a pile of gear.) but if I remember correctly the HRO receiver (at least the early, pre-war, ones) had a 'non-contact' crystal holder for the IF notch filter. The crystal was a block about 1/2 square and a bit less thick (-ish) and fitted loosely between two support plates which incorporated the electrodes. It was certainly not a tight fit and the crystal could be easily removed. Paul ReevesG8GJA -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chuck Harris Sent: 21 April 2014 14:01 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] optically excite a quartz crystal? I'm puzzling over this statement. The FT-243's I have seen have a spring that squishes the quartz blank between the electrodes. They aren't plated onto the quartz, but they are still in intimate mechanical and electrical contact. -Chuck Harris Bob Camp wrote: Hi The WWII era FT-243 is one example of a crystal that has the active portion of the electrodes separated from the resonator by an air gap. There are lots of similar holders from that era that do pretty much the same thing. Non-contacting electrodes are not very new. Bob ___ 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] DCF77/PZF correlation after outage
Ben, sorry for the late reply due to the Easter holidays. Ben wrote: Hi Group, At the 14th of april 2014 between 17:00 and 18:00 hours UTC there was a DCF77 outage. I have a NTP server with DCF77/PZF receiver (lantime m200) which i monitor. I noticed that the PZF correlation is slowly comming back to nomal (90%) level, instead of after a few minutes just like the field strength level. Below are links to my graph and the Kiel VLF monitor graph. Field strength and PZF Correlation graph: http://imgur.com/gdosBhs Hm, the description embedded in the graph says the *yellow* line shows the *correlation* which is immediately coming back after the outage, as expected. The blue line sould be the field strength, which is indeed increasing very slowly. I'm not sure how you have extracted the field strength from the M200, but this is probably only some AGC control value which just needs to be sufficient to yield proper correlation. There is no parameter available in the LANTIME which reports the true DCF77 field strength. Kiel VLF monitor graph: http://imgur.com/DC9yDrQ Several devices running here at the factory (Meinberg) have also observed the short outage. Please keep in mind that unlike the British MSF the German DCF77 transmitter usually has no scheduled outages, and as far as I know is only put out of operation for a short time if there is a really heavy thunderstorm. I hope someone has an explanation or suggestion I can learn from :) Best regards, Martin -- Martin Burnicki Senior Software Engineer MEINBERG Funkuhren GmbH Co. KG Email: martin.burni...@meinberg.de Phone: +49 (0)5281 9309-14 Fax: +49 (0)5281 9309-30 Lange Wand 9, 31812 Bad Pyrmont, Germany Amtsgericht Hannover 17HRA 100322 Geschäftsführer/Managing Directors: Günter Meinberg, Werner Meinberg, Andre Hartmann, Heiko Gerstung Web: http://www.meinberg.de ___ 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] DCF77/PZF correlation after outage
Martin, Thanks for your reply. The correlation coefficient is almost back at the normal level. I will search some old logs to see if previous outages also shows the same behaviour. It could be perfectly normal. Hm, the description embedded in the graph says the *yellow* line shows the *correlation* which is immediately coming back after the outage, as expected. I am sorry, my mistake, I've created a new graph. http://i.imgur.com/hv9gSvu.png The blue line sould be the field strength, which is indeed increasing very slowly. I'm not sure how you have extracted the field strength from the M200, but this is probably only some AGC control value which just needs to be sufficient to yield proper correlation. There is no parameter available in the LANTIME which reports the true DCF77 field strength. The data is extracted via SNMP. According to the MIB: mbgLtNgRefclockStatusA - pzf : correlation mbgLtNgRefclockStatusB - all : field strength Version: LANTIME V6.14.021 Best regards, Ben ___ 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] hp 54600a and rs-232
While only related to time nuttery in the sense of the hp 54600a being an instrument (oscilloscope) which we nuts might use make some meaningful measurements, I am hoping that members of this list vast knowledge of many such instruments may be able to help or at least point me in the right direction. I recently obtained a hp 54600a digital oscilloscope in very good condition and while not a modern whiz bang high bandwidth and high speed instrument it is quite capable and compliments my old Tektronix 5440 scope quite nicely. My 54600a has the basic RS-232 interface module which seems to work OK. I am able to select print screen and send data from the scope to an HP plotter or printer - computer actually which collects the data stream and converts the hgl data into a png file using a simple script. However, my attempts at getting the scope to respond to commands via the RS-232 serial interface are for naught. I am using a USB to RS-232 converter and an appropriate null modem cable. I don't have a proper serial port to try however. When I send commands to the scope it will display framing error or overrun or rs-232 error (113) or rs-232 error (118) (I can't find either error code listed in the hp documents). Being able to capture a screen dump is my primary concern and I am able to do so, controlling the scope via rs-232 as I might using a gpib/hpib interface is only secondary but still, it would be nice to know why my limited attempts have so far not worked. Ideas? Comments? Suggestions? Cheers, Graham ve3gtc ___ 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] First success with very simple, very low cost GPSDO, under $8
Hi! If it is all the same for you, I prefer this thread continue in the open as I am interested both in using an Arduino-like for my first GPSDO and STM32 for event capture and timming. Regards, Edésio On Mon, Apr 21, 2014 at 04:29:35PM -0400, paul swed wrote: Good afternoon very interested in the work you are doing with the STM board. As I mentioned far earlier in this thread I am attempting to use it to correct the BPSK WWVB signal here. Initial thoughts were using FORTH to program the STM board. Very curious what you are using as examples. My experience in FORTH is from many years ago and have done very poorly at C. But this may be the case to have something of interest to actually do. In either language. Regards Paul WB8TSL On Mon, Apr 14, 2014 at 12:27 PM, d0ct0r t...@patoka.org wrote: I was experimenting with the same setup for STM32 MCU. This microprocessor has accept the sine wave from external OCXO or GPSDO. No problem with this. The only thing: I was need to start MCU from slow watch crystal first. And then switch it to work to external one. In another case I got incorrect timing settings for MCU. Later, I decide to implement LTC6957-3 chip to share REFCLOCK source, since that chip has two equal CMOS-level outputs. Unfortunately I have no tool to measure the phase noise and jitters on each setup. It turns out all of this is built into the AVR chip. There is a counter and logic to copy the current counter value to a register on a PPS pulse raising edge.The counter keeps running and every second its value is trapped. I can connect the OCXO and the PPS directly to the AVR pin. The AVR has hardware (a fast comparator) to square a low amplitude sine wave and trap the counter on a zero crossing. So it looks like I can get rid of ALL of the external chips. The built in DAC is working well also but it needs some external resisters and caps. No need for '74 FFs or '373' or counter chips.I do get precision timing with no time critical software, no 74xxx chips. -- WBW, V.P. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ 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] hp 54600a and rs-232
This may help: http://cp.literature.agilent.com/litweb/pdf/54652-97004.pdf Thomas Knox From: coll...@navcanada.ca To: time-nuts@febo.com Date: Tue, 22 Apr 2014 07:21:22 -0400 Subject: [time-nuts] hp 54600a and rs-232 While only related to time nuttery in the sense of the hp 54600a being an instrument (oscilloscope) which we nuts might use make some meaningful measurements, I am hoping that members of this list vast knowledge of many such instruments may be able to help or at least point me in the right direction. I recently obtained a hp 54600a digital oscilloscope in very good condition and while not a modern whiz bang high bandwidth and high speed instrument it is quite capable and compliments my old Tektronix 5440 scope quite nicely. My 54600a has the basic RS-232 interface module which seems to work OK. I am able to select print screen and send data from the scope to an HP plotter or printer - computer actually which collects the data stream and converts the hgl data into a png file using a simple script. However, my attempts at getting the scope to respond to commands via the RS-232 serial interface are for naught. I am using a USB to RS-232 converter and an appropriate null modem cable. I don't have a proper serial port to try however. When I send commands to the scope it will display framing error or overrun or rs-232 error (113) or rs-232 error (118) (I can't find either error code listed in the hp documents). Being able to capture a screen dump is my primary concern and I am able to do so, controlling the scope via rs-232 as I might using a gpib/hpib interface is only secondary but still, it would be nice to know why my limited attempts have so far not worked. Ideas? Comments? Suggestions? Cheers, Graham ve3gtc ___ 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] hp 54600a and rs-232
Thank you Thomas, I have that document but it wasn't of much help. I spent much time over the weekend reading through the various hp documents for this scope and interfaces but it did not shed any light on the subject. Cheers, Graham -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Knox Sent: April-22-14 10:28 AM To: Time-Nuts Subject: Re: [time-nuts] hp 54600a and rs-232 This may help: http://cp.literature.agilent.com/litweb/pdf/54652-97004.pdf Thomas Knox From: coll...@navcanada.ca To: time-nuts@febo.com Date: Tue, 22 Apr 2014 07:21:22 -0400 Subject: [time-nuts] hp 54600a and rs-232 While only related to time nuttery in the sense of the hp 54600a being an instrument (oscilloscope) which we nuts might use make some meaningful measurements, I am hoping that members of this list vast knowledge of many such instruments may be able to help or at least point me in the right direction. I recently obtained a hp 54600a digital oscilloscope in very good condition and while not a modern whiz bang high bandwidth and high speed instrument it is quite capable and compliments my old Tektronix 5440 scope quite nicely. My 54600a has the basic RS-232 interface module which seems to work OK. I am able to select print screen and send data from the scope to an HP plotter or printer - computer actually which collects the data stream and converts the hgl data into a png file using a simple script. However, my attempts at getting the scope to respond to commands via the RS-232 serial interface are for naught. I am using a USB to RS-232 converter and an appropriate null modem cable. I don't have a proper serial port to try however. When I send commands to the scope it will display framing error or overrun or rs-232 error (113) or rs-232 error (118) (I can't find either error code listed in the hp documents). Being able to capture a screen dump is my primary concern and I am able to do so, controlling the scope via rs-232 as I might using a gpib/hpib interface is only secondary but still, it would be nice to know why my limited attempts have so far not worked. Ideas? Comments? Suggestions? Cheers, Graham ve3gtc ___ 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] hp 54600a and rs-232
Framing error or override sounds like a parity or stop bit issues. Have you changed those at all? 7E2 often works when 8N1 is specified. On Apr 22, 2014, at 10:34, Collins, Graham coll...@navcanada.ca wrote: Thank you Thomas, I have that document but it wasn't of much help. I spent much time over the weekend reading through the various hp documents for this scope and interfaces but it did not shed any light on the subject. Cheers, Graham -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Knox Sent: April-22-14 10:28 AM To: Time-Nuts Subject: Re: [time-nuts] hp 54600a and rs-232 This may help: http://cp.literature.agilent.com/litweb/pdf/54652-97004.pdf Thomas Knox From: coll...@navcanada.ca To: time-nuts@febo.com Date: Tue, 22 Apr 2014 07:21:22 -0400 Subject: [time-nuts] hp 54600a and rs-232 While only related to time nuttery in the sense of the hp 54600a being an instrument (oscilloscope) which we nuts might use make some meaningful measurements, I am hoping that members of this list vast knowledge of many such instruments may be able to help or at least point me in the right direction. I recently obtained a hp 54600a digital oscilloscope in very good condition and while not a modern whiz bang high bandwidth and high speed instrument it is quite capable and compliments my old Tektronix 5440 scope quite nicely. My 54600a has the basic RS-232 interface module which seems to work OK. I am able to select print screen and send data from the scope to an HP plotter or printer - computer actually which collects the data stream and converts the hgl data into a png file using a simple script. However, my attempts at getting the scope to respond to commands via the RS-232 serial interface are for naught. I am using a USB to RS-232 converter and an appropriate null modem cable. I don't have a proper serial port to try however. When I send commands to the scope it will display framing error or overrun or rs-232 error (113) or rs-232 error (118) (I can't find either error code listed in the hp documents). Being able to capture a screen dump is my primary concern and I am able to do so, controlling the scope via rs-232 as I might using a gpib/hpib interface is only secondary but still, it would be nice to know why my limited attempts have so far not worked. Ideas? Comments? Suggestions? Cheers, Graham ve3gtc ___ 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] hp 54600a and rs-232
The scope has four choices for baud rate and otherwise is 8 databits, 1 stop bit, and no parity. I am not sure I understand what you are suggesting with the 7E2 - set my program to use 7 data bits EVEN parity and 2 stop bits? Cheers, Graham -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of bownes Sent: April-22-14 10:48 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] hp 54600a and rs-232 Framing error or override sounds like a parity or stop bit issues. Have you changed those at all? 7E2 often works when 8N1 is specified. On Apr 22, 2014, at 10:34, Collins, Graham coll...@navcanada.ca wrote: Thank you Thomas, I have that document but it wasn't of much help. I spent much time over the weekend reading through the various hp documents for this scope and interfaces but it did not shed any light on the subject. Cheers, Graham -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Knox Sent: April-22-14 10:28 AM To: Time-Nuts Subject: Re: [time-nuts] hp 54600a and rs-232 This may help: http://cp.literature.agilent.com/litweb/pdf/54652-97004.pdf Thomas Knox From: coll...@navcanada.ca To: time-nuts@febo.com Date: Tue, 22 Apr 2014 07:21:22 -0400 Subject: [time-nuts] hp 54600a and rs-232 While only related to time nuttery in the sense of the hp 54600a being an instrument (oscilloscope) which we nuts might use make some meaningful measurements, I am hoping that members of this list vast knowledge of many such instruments may be able to help or at least point me in the right direction. I recently obtained a hp 54600a digital oscilloscope in very good condition and while not a modern whiz bang high bandwidth and high speed instrument it is quite capable and compliments my old Tektronix 5440 scope quite nicely. My 54600a has the basic RS-232 interface module which seems to work OK. I am able to select print screen and send data from the scope to an HP plotter or printer - computer actually which collects the data stream and converts the hgl data into a png file using a simple script. However, my attempts at getting the scope to respond to commands via the RS-232 serial interface are for naught. I am using a USB to RS-232 converter and an appropriate null modem cable. I don't have a proper serial port to try however. When I send commands to the scope it will display framing error or overrun or rs-232 error (113) or rs-232 error (118) (I can't find either error code listed in the hp documents). Being able to capture a screen dump is my primary concern and I am able to do so, controlling the scope via rs-232 as I might using a gpib/hpib interface is only secondary but still, it would be nice to know why my limited attempts have so far not worked. Ideas? Comments? Suggestions? Cheers, Graham ve3gtc ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Very slow freq. counter / event counter
On Fri, Apr 18, 2014 at 02:48:09PM -0700, Chris Albertson wrote: This chip does what you want: http://leapsecond.com/pic/picpet.htm Input frequency is 0.01 Hz to 100 Hz. Output is microsecond time-stamp and event-count over RS232. PCs can do that without the chip. Connect the pulse to the DCD line of an RS232 port and it will get logged with a uSec timestamp. It works for any frequency from maybe 1kHz to 0Hz. The port tolerates volts from -12 to +12.I don't think you need any add chip to log pulses. Hello all, and thank you for the ideas. I have read here many times about the linux PPS interface, but I never managed to try it. I use linux as my main OS since 1994 so it's interesting to note I ought to have tried it before :) However, and the same could be told about the very interesting picpet, I would have liked more a self contained solution: you stick two alligator clips and read numbers, like a DMM. The HP 5334/5335 Javier and Magnus suggested are a step in the right direction, but unfortunately, they cannot be found cheaply here in Italy and they are big for the needs like my Racal Dana 1992. What are using high school labs to time motion physics experiments? I remember we had an electromechanical stopwatch with contacts for start and stop, but it was obsolete already then so they must have something electronic, or everyone use a PC now? Maybe the educational field has his own very specific devices. Best regards, Andrea Baldoni ___ 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] hp 54600a and rs-232
Yup, set your program to 7E2 and test it. I would fire up a terminal program like hyperterm and see if you can talk to it manually before anything else. With only four baud rates to check, it isn't too many combinations. Not many things support split baud rates (different rate for rx and tx), but if it does, make sure they are the same. You can also try looping back the tx/rx pins on the rs232 port from the computer to check that out standalone first. That should work at any baud rate and parity setting. Bob On Tue, Apr 22, 2014 at 11:07 AM, Collins, Graham coll...@navcanada.cawrote: The scope has four choices for baud rate and otherwise is 8 databits, 1 stop bit, and no parity. I am not sure I understand what you are suggesting with the 7E2 - set my program to use 7 data bits EVEN parity and 2 stop bits? Cheers, Graham -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of bownes Sent: April-22-14 10:48 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] hp 54600a and rs-232 Framing error or override sounds like a parity or stop bit issues. Have you changed those at all? 7E2 often works when 8N1 is specified. On Apr 22, 2014, at 10:34, Collins, Graham coll...@navcanada.ca wrote: Thank you Thomas, I have that document but it wasn't of much help. I spent much time over the weekend reading through the various hp documents for this scope and interfaces but it did not shed any light on the subject. Cheers, Graham -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Knox Sent: April-22-14 10:28 AM To: Time-Nuts Subject: Re: [time-nuts] hp 54600a and rs-232 This may help: http://cp.literature.agilent.com/litweb/pdf/54652-97004.pdf Thomas Knox From: coll...@navcanada.ca To: time-nuts@febo.com Date: Tue, 22 Apr 2014 07:21:22 -0400 Subject: [time-nuts] hp 54600a and rs-232 While only related to time nuttery in the sense of the hp 54600a being an instrument (oscilloscope) which we nuts might use make some meaningful measurements, I am hoping that members of this list vast knowledge of many such instruments may be able to help or at least point me in the right direction. I recently obtained a hp 54600a digital oscilloscope in very good condition and while not a modern whiz bang high bandwidth and high speed instrument it is quite capable and compliments my old Tektronix 5440 scope quite nicely. My 54600a has the basic RS-232 interface module which seems to work OK. I am able to select print screen and send data from the scope to an HP plotter or printer - computer actually which collects the data stream and converts the hgl data into a png file using a simple script. However, my attempts at getting the scope to respond to commands via the RS-232 serial interface are for naught. I am using a USB to RS-232 converter and an appropriate null modem cable. I don't have a proper serial port to try however. When I send commands to the scope it will display framing error or overrun or rs-232 error (113) or rs-232 error (118) (I can't find either error code listed in the hp documents). Being able to capture a screen dump is my primary concern and I am able to do so, controlling the scope via rs-232 as I might using a gpib/hpib interface is only secondary but still, it would be nice to know why my limited attempts have so far not worked. Ideas? Comments? Suggestions? Cheers, Graham ve3gtc ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Very slow freq. counter / event counter
What are using high school labs to time motion physics experiments? Video cameras. There are LED gadgets that blink fast enough to work well for that sort of thing. www.exploratorium.edu/baseball/ScienceOfBaseballTour.pdf -- 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] GPSDO and holdover
Hi Bob S, I have noticed skipped 1PPS on the Adafruit GPS also. Some days are clean, other days miss a few samples. I have not explained it yet. I plan to run two GPS boards and two counters to narrow down the cause. In any event, IMHO, a GPSDO should not go crazy if glitches like this occur. I don't think it should go into holdover for one missed sample, or even a few missed samples. But then you need to define what holdover is. I mean, by some definition a GPSDO is in holdover between every second. I do not think there is any standard. Just conventions: some documented, some not. It's attention to a dozen little details like this that separate a quick hack GPSDO from a quality one. You'll also face a number of design issues at startup, and coming out of holdover. Lastly, you get to choose between it being an ideal time standard vs. an ideal frequency standard. /tvb p.s. Please fix your address book. The correct email for the list is time-nuts@febo.com - Original Message - From: Bob Stewart To: time-nuts-ow...@febo.com Sent: Tuesday, April 22, 2014 6:03 PM Subject: GPSDO and holdover I hope I haven't asked this before, but is there a standard way of deciding to go into holdover mode? I'm still wrapping up code for this Adafruit, and as I've posted before: every now and then it skips a PPS. I'm trying to decide whether to allow a free pass (if not followed by another skip within some timeframe) or to immediately stop processing any further PPS pulses until I decide based on some criteria that they're reliable. Bob - AE6RV ___ 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] GPSDO and holdover
Hi Tom, Thanks for confirming that these lost PPS pulses are happening to someone else! I've looked through my interrupt code several times to see if I'm missing something. Please let me know if you find anything for sure. I've been thinking of saving the values for the satellites at each tick to see if it's related to AOS/LOS, but there's been too much else to do. I've already faced most of the points you make, and yeah, the decision on whether to have ideal time or ideal frequency has been a difficult one. But, there's only so much I can do with a nav receiver. I'll address it when a timing receiver goes in. I think I'll go ahead and loosen up my definition of what holdover is, as a strict interpretation seems to cause more damage than it prevents. Bob From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, April 22, 2014 8:57 PM Subject: Re: [time-nuts] GPSDO and holdover Hi Bob S, I have noticed skipped 1PPS on the Adafruit GPS also. Some days are clean, other days miss a few samples. I have not explained it yet. I plan to run two GPS boards and two counters to narrow down the cause. In any event, IMHO, a GPSDO should not go crazy if glitches like this occur. I don't think it should go into holdover for one missed sample, or even a few missed samples. But then you need to define what holdover is. I mean, by some definition a GPSDO is in holdover between every second. I do not think there is any standard. Just conventions: some documented, some not. It's attention to a dozen little details like this that separate a quick hack GPSDO from a quality one. You'll also face a number of design issues at startup, and coming out of holdover. Lastly, you get to choose between it being an ideal time standard vs. an ideal frequency standard. /tvb p.s. Please fix your address book. The correct email for the list is time-nuts@febo.com - Original Message - From: Bob Stewart To: time-nuts-ow...@febo.com Sent: Tuesday, April 22, 2014 6:03 PM Subject: GPSDO and holdover I hope I haven't asked this before, but is there a standard way of deciding to go into holdover mode? I'm still wrapping up code for this Adafruit, and as I've posted before: every now and then it skips a PPS. I'm trying to decide whether to allow a free pass (if not followed by another skip within some timeframe) or to immediately stop processing any further PPS pulses until I decide based on some criteria that they're reliable. Bob - AE6RV ___ 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] HP Z3805A GPSDO Oven Heater Voltages
I have a HP Z3805A / 58503A with a cold outer oven. I have installed another HP 10811-60165 DOXO, and then another power board. Still, the outer oven is not heating. Heater resistance is ok at 19 ohm, but voltage on red wires to heater are both at 5.0 VDC. On another (good warm) HP Z3805A, the red wire voltage on P3-3 is at 15.27 V, so there is current flow through the heater and the DOXO is nice and warm. I found two other voltage differences on the power board terminals: P2-8 Violet = 0.00 V vs. 4.5 on the good unit P2-9 Green = 8.14 V vs. 1.95 V on the good unit So, can someone tell me what the green and violet wires do that connect to the main circuit board? Any suggestions on how / what to troubleshoot next? John Stuart, KM6QX Lafayette, CA ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO and holdover
On Tue, Apr 22, 2014 at 6:57 PM, Tom Van Baak t...@leapsecond.com wrote: I do not think there is any standard. Just conventions: some documented, some not. It's attention to a dozen little details like this that separate a quick hack GPSDO from a quality one. You'll also face a number of design issues at startup, and coming out of holdover. Lastly, you get to choose between it being an ideal time standard vs. an ideal frequency standard. The simplest thing, I think is to use the GPS' serial data stream to decide if you are in holdover or not. There will be a status message that says if the GPS is producing valid output. The details depend on the GPS but most have something to describe the number of GPS satellites in view and something about each of them. -- 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.
