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: [email protected] [mailto:[email protected]] 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 <[email protected]> > 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 -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
