[time-nuts] WWVB BPSK Receiver Project? (fwd)

[Marek Peca]

Dear Poul-Henning,

>> My only argument against your versatile and well-performing solution is
>> that it is a little bit overkill.
>
> As if running a handfull precision oscillators just for fun isn't
> "overkill" also ? :-)

I don't know -- are there any limits for the fun in a time-nut sense? :-)
I hope not. The point is, with which kind of toy we would like to play.

>> In other words, it would be certainly better to buy USRP N210,
>
> Actually that would be a very idea, because you cannot get rid of
> the down-sampler in the USRP and that would make Loran-C reception
> very tricky to implement.

Are you sure there are such a limitations? I must reveal, that I have not 
even once played with USRP N210, but I hope it does not have any BW 
limitations up to the Gig-Eth speed.

Anyway, it would be an expensive and heavy receiver for LF-only signals.

>> My point is to do something with relevant performance wrt. <10kHz wide
>> LF signals.
>
> The crucial question is if your are doing timenuttery or radionuttery.
>
> If you are doing timenuttery, you want you ADC synchronized to your
> OCXO/Rb/Cs or whatever you have,

Yes, I would like to have an option of external frequency standard.
However, I would like to lock ordinary onboard quartz too, since many 
people without Rb (though they are pretty cheap these days) may use it as 
a disciplined frequency source, too. I mean no time-nuts, but ordinary 
hobbyists, going to tune their filters etc.

Or people, wanting some time signal in place of poor GNSS reception 
without good NTP access (I know such a set i almost empty :-)).

> and you don't want to have to deal with getting your IF frequency locked 
> too.
>
> Soundcards use inconvenient frequencies and are seldom built to take
> an external clock signal.

So this is why I would like to supply a little bit tweaked "sound card", 
tailored to receive LF-HF band signals up to say 10..20kHz of width.

>> The useful bandwidth of LF to HF radio is about 9kHz,
>
> You need more than 25kHz for good Loran-C

OK, thank you for this notice. I have not yet thinked about Loran, so I 
must look in more detail on it.


Best regards,
Marek