I believe Gray code was invented to support absolute mechanical position encoders, where the speed of the electronics is high compared to the speed of the hardware being monitored. It eliminates the potentially large error between two positions since only one bit changes at a time. This is done at the expense of complicated logic, which goes against speed.
I don't think Gray code has ever been used to implement fast electronic counters. That's what synchronous counters are for, and when synchronous counters are not fast enough, use a prescaler. It will just take more time to get the precision you need. Unless you need fractional Hz resolution at THz speed, a prescaler is the way to go. Didier ------------------------ Sent from my BlackBerry Wireless thingy while I do other things... -----Original Message----- From: Eugen Leitl <eu...@leitl.org> Date: Thu, 15 Apr 2010 13:42:00 To: <time-nuts@febo.com> Subject: Re: [time-nuts] lunatic fringe time standards On Thu, Apr 15, 2010 at 07:30:27AM -0400, Bob Camp wrote: > Hi > > I'm not 100% sure I understand exactly what you are thinking about setting up. This is completely theoretical at this point. Just the required geometry size would be prohibitive. > My guess is that the counter needs to run at the same THz speed as > the oscillator. That's pretty fast. I suspect that what ever you use, > speed / propagation delay in the counter it's self will be an issue. > That will get you back to either a ripple counter or a Johnson counter. Wouldn't you get large errors when you caught a ripple during readout? That wouldn't be a problem with a Gray code. -- Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE _______________________________________________ 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.