You have not answered my question. Yes or no, do you have it working on the new WWVB format?
-John ================= > Hi > > The issue is dithering the input to the ADC. If you filter "to much" you > get > to the point that you are not dithering very much. That actually reduces > the > linearity of many ADC's (ie spurs go up). It very much impacts your > ability > to pull out low level signals. > > Done that? yes lots of times. Got it working? yup. It's a very standard > text > book approach that's been around for many decades. > > Can you carry dithering too far? Indeed you can. You do not want to > overload > the ADC. Once it's clipping, you aren't getting anything useful out of it. > > Things like broadcast AM and switching power supplies are both threats to > your receiver. If your loop antenna has a Q of 100 or so, it's going to > have > a bandwidth of about 600 Hz. That eliminates the AM band pretty well. > Switchers can be anywhere, yes you might have one at exactly 60.0001 KHz. > Call up Javad for a brick wall filter in that case. > > Your 600 Hz wide antenna has taken out a lot of noise. More than likely, > your ADC isn't getting much into it. A 6KHz wide antenna would still kill > the AM band. The lower Q antenna also may give you less trouble over > temperature. Where between Q=10 and Q=100 you get reasonable dithering > *and* > nuke your local crud *and* get a reasonably stable system.... TBD. > > Bob > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of J. Forster > Sent: Wednesday, September 26, 2012 9:18 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] WWVB PM Receiver > > Have you actually tried it and gotten it working, except possibly in a > very strong signal area? > > -John > > ================ > > > >> Hi, >> >> From: "Bob Camp" <[email protected]> >> >>> A tuned antenna probably is going to provide all the selectivity you'd >>> need. >> Another possibility is to modify your old circuit like that: >> http://www.maxmcarter.com/rubidium/2012_mod/index.html >> >> Bye, >> Jean-Louis >> >> _______________________________________________ >> 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. > > > _______________________________________________ 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.
