Curious as to what you did in some detail. I use SXB basic which can run in sub microsecond loops or a max clock of 75 Mhz. But anything I would tend to do would not have the precision of what Poul suggests. He is using larger numbers and it makes sense to use a DSP chip set for the math suggested. Unfortunately I have just about 0 ability to do that. However Pouls final sentence does lead back for me at least to the real interest. Load everything into a spreadsheet and produce a number on the local reference as compared to GPS. But potentially at a lower resolution. I have been spoiled by the austrons loran timing receivers and GPS also. Reference in 1 X 10^ -12 out.... Regards Paul.
On Wed, Mar 30, 2011 at 2:59 AM, Don Latham <d...@montana.com> wrote: > I've had some success with control programs done in Robot Basic > www.robotbasic.org . > the price is right, and it's designed for i/o with simple tools built-in. > Check it out. > Don > > ----- Original Message ----- From: "paul swed" <paulsw...@gmail.com> > To: "Discussion of precise time and frequency measurement" < > time-nuts@febo.com> > Sent: Tuesday, March 29, 2011 7:57 AM > Subject: Re: [time-nuts] WWVB Measurements using DSP recovery > > > > Now you see I like these up to date solutions with cheap components. I >> recently home brewed "YAGPSDO" yet another GPSDO, just to see how its >> done. >> When I look at things like a frontend and maybe a mixer thats easy stuff. >> Even adding a nice A/D converter etc is easy if you can solder the darn >> things. >> What gets tricky is indeed the programming of the processor. I would have >> to >> say on the GPSDO its really not much more then a single loop pid with just >> a >> drop of smarts. >> So back to this. >> I have read the high level comments. But can we get deeper detail. Can it >> be >> done lets say in basic language etc. The comment I read that struck a cord >> was that all you did was sample and put the information in roughly 1000 >> bins. Then I assume look for the bin with the most counts and called that >> center frequency. Perhaps plotting that number out. >> Is that really it??? Sure various filtering could also be done. >> But if the above scenario were correct for me at least it gets interesting >> and do-able. >> By the way for definition my interest is indeed an alternate comparison >> method to GPS. Kind of a second reference since we lost loran. >> >> Having just wrapped up my project with VE2ZAZ for the HP3586 DSS its time >> to >> move on to the tracor 599 and wwvb. >> Regards >> Paul >> >> On Tue, Mar 29, 2011 at 2:54 AM, Poul-Henning Kamp <p...@phk.freebsd.dk >> >wrote: >> >> In message <4d9129d8.4060...@comcast.net>, Greg Broburg writes: >>> >>> >Can you show a circuit of what you have done? >>> >>> Basically I have a 20MSPS PCI card in a PC and do it all in >>> software. >>> >>> I did use similar principles to implement a LORAN-C receiver >>> in a aduc7216 (http://phk.freebsd.dk/AducLoran/) but that is >>> passe for US people now. >>> >>> >Would you recommend the 7200 again or something >>> >else that is better suited? >>> >>> The most user friendly way to do it, would be to have a small FPGA >>> which takes data from the ADC and averages it into a small piece >>> of multiplext or dual port RAM, and a microcontroller (ARM ?) on >>> the other port, doing all the high level stuff. >>> >>> That way there is no real-time component to deal with in the >>> programming, and anybody should be able to play with the code. >>> >>> The alternative is to use a DSP to read the ADC, do the >>> averaging and perform the high level functions. That would >>> be a lot harder to program for most people. >>> >>> The ADC could be 16 bits, and run directly from a house standard >>> of 5 or 10 MHz (looks like that would cost $4 from analog.com, isn't >>> this future amazing ?) >>> >>> Add a high resolution DAC for steering OCXO's and a serial port >>> or USB interface and we're done... >>> >>> -- >>> 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. >>> >>> _______________________________________________ >> 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.