Re: [time-nuts] TEC party: hardware suggestion
In thinking about how to implement a scheme to make the phase and frequency comparison using what I have on hand, I considered the following as a possibility: An ARB with a GPS derived 10 MHz reference set to 60 Hz. The one I have has a very low jitter spec. It actually is a dual ARB so I could use the 2nd independent channel to calibrate the phase detector A phase comparator, which I would have to construct or buy. The phase difference output would be a DC voltage that could be calibrated. This is the only piece that I know little about so suggestions on how to create this would be appreciated. A 2-channel digital scope? A simple IC comparator? Hey, it's only 60 Hz, how tough could it be? A 6-1/2 digit DMM that could either be polled at intervals of a few mSec, or could be set to capture a number of readings for transfer to the PC. In either case the data could be time-stamped. Sounds like fun! Tom Holmes, N8ZM Tipp City, OH EM79 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Thursday, June 30, 2011 12:28 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] TEC party: hardware suggestion On Thu, Jun 30, 2011 at 1:38 AM, Achim Vollhardt avoll...@physik.uzh.ch wrote: Time-Nutties, how about using a small uC (PIC/AVR) clocked with 100ns instruction speed. Start = 1PPS from GPS, Stop = 60 Hz Edge? Use internal capture hardware to count processor cycles in between. Recently posted plots show that all you need is an AC wall wart transformer and two resistors. a uC is total overkill The xformer and resistor voltage divider works because by dumb luck the pin in the rs232 port was designed to accept a signal that looks a lot like low voltage AC and even better, already has edge detection built in. Also by dumb luck someone already wrote the software to monitor the pin's status and time stamp transitions. This really is a case of pure luck. -- 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. ___ 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] TEC party: hardware suggestion
Posted to this list just minutes before is a live on-line measurement demo. The hardware used is pretty simple. Just four inexpensive parts (and a computer) http://websdr.ewi.utwente.nl:8901/lichtnet/ On Fri, Jul 1, 2011 at 10:08 AM, Tom Holmes thol...@woh.rr.com wrote: In thinking about how to implement a scheme to make the phase and frequency comparison using what I have on hand, I considered the following as a possibility: An ARB with a GPS derived 10 MHz reference set to 60 Hz. The one I have has a very low jitter spec. It actually is a dual ARB so I could use the 2nd independent channel to calibrate the phase detector A phase comparator, which I would have to construct or buy. The phase difference output would be a DC voltage that could be calibrated. This is the only piece that I know little about so suggestions on how to create this would be appreciated. A 2-channel digital scope? A simple IC comparator? Hey, it's only 60 Hz, how tough could it be? A 6-1/2 digit DMM that could either be polled at intervals of a few mSec, or could be set to capture a number of readings for transfer to the PC. In either case the data could be time-stamped. Sounds like fun! Tom Holmes, N8ZM Tipp City, OH EM79 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Thursday, June 30, 2011 12:28 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] TEC party: hardware suggestion On Thu, Jun 30, 2011 at 1:38 AM, Achim Vollhardt avoll...@physik.uzh.ch wrote: Time-Nutties, how about using a small uC (PIC/AVR) clocked with 100ns instruction speed. Start = 1PPS from GPS, Stop = 60 Hz Edge? Use internal capture hardware to count processor cycles in between. Recently posted plots show that all you need is an AC wall wart transformer and two resistors. a uC is total overkill The xformer and resistor voltage divider works because by dumb luck the pin in the rs232 port was designed to accept a signal that looks a lot like low voltage AC and even better, already has edge detection built in. Also by dumb luck someone already wrote the software to monitor the pin's status and time stamp transitions. This really is a case of pure luck. -- 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. ___ 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.
[time-nuts] TEC party: hardware suggestion
Time-Nutties, how about using a small uC (PIC/AVR) clocked with 100ns instruction speed. Start = 1PPS from GPS, Stop = 60 Hz Edge? Use internal capture hardware to count processor cycles in between. Send output once per second via FT232(USB) to host PC.. alternatively store locally on SD card.. This could be a tiny add-on card in main-powered GPS setups.. Sorry for not jumping on the soundcard-software approach.. I'm a hardware guy and my programming skills suck.. :) Regards, Achim ___ 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] TEC party: hardware suggestion
In message 4e0c35ff.8050...@physik.uzh.ch, Achim Vollhardt writes: Time-Nutties, how about using a small uC (PIC/AVR) clocked with 100ns instruction speed. Start = 1PPS from GPS, Stop = 60 Hz Edge? Use internal capture hardware to count processor cycles in between. If you really want to do this: Sample the mains signal with an ADC at around 1000kHz. Mix it down to baseband, calculate I/Q magnitudes and use ATAN2 to find phase. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TEC party: hardware suggestion
Hi Poul, I would guess the 100ns granularity should be already overkill, giving an error in the order of 1e-7. To be compared with mains instability of 1e-5: http://www.leapsecond.com/pages/mains/ I would try to keep it as simple as possible... maybe even only one IC, there exist USB-capable PIC controllers (don't know about AVR, but likely as well). Regards, Achim ___ 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] TEC party: hardware suggestion
On Thu, Jun 30, 2011 at 1:38 AM, Achim Vollhardt avoll...@physik.uzh.ch wrote: Time-Nutties, how about using a small uC (PIC/AVR) clocked with 100ns instruction speed. Start = 1PPS from GPS, Stop = 60 Hz Edge? Use internal capture hardware to count processor cycles in between. Recently posted plots show that all you need is an AC wall wart transformer and two resistors. a uC is total overkill The xformer and resistor voltage divider works because by dumb luck the pin in the rs232 port was designed to accept a signal that looks a lot like low voltage AC and even better, already has edge detection built in. Also by dumb luck someone already wrote the software to monitor the pin's status and time stamp transitions. This really is a case of pure luck. -- 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.
