[time-nuts] WWVB Measurements using DSP recovery

[paul swed]

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 <djl at 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" <paulswedb at gmail.com>
> To: "Discussion of precise time and frequency measurement" <
> time-nuts at 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 <phk at phk.freebsd.dk
>> >wrote:
>>
>>  In message <4D9129D8.4060609 at 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
>>> phk at 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 at 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 at 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 at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>