[time-nuts] wtd: WWVB info

Bob Camp kb8tq at n1k.org
Wed Aug 5 07:15:03 EDT 2015


The front end would be “dealers choice”. He who does the
project gets to decide what gets used.

If you look over some other designs, you can indeed get 
a device going with a 12 bit converter. The qualifier is that
the signal to noise needs to be pretty good. With fades 
and switcher interference, you probably would notice its

The “other end” of the design spectrum would be with a part
designed as a high range font end chip. You can get to a lot
of bits at low frequency. Even the prices aren’t all that crazy. 

Is there one and only one approach here? Not in any way. There
are several thousand possible ways to do it. AGC or no AGC would 
be a pretty major decision. Next decision would be things like clocks.
15 MHz from a ($25) KS box that also puts out 10 MHz looks like a 
pretty good choice at the moment. 

Past that it’s decimators / filters and the usual DSP stuff (or any of
a dozen alternatives). Given the high noise environment I’d lean towards
a DSP approach. 

Most of the choices run into the easy / quick / cheap tradeoff triangle. I’m
sure that the debating process can find a solution that should “cost 10 cents”. I’m
also sure that a basement lash up of available parts is quick, but hard to reproduce. 
I’m not terribly surprised at the lack of 10 cent solutions. I’m a bit surprised
that there are no unique lash up designs. The debate process seems to 
have made this a pretty un-attractive thing to do. 


> On Aug 4, 2015, at 11:36 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
> kb8tq at n1k.org said:
>> So far there have not been any home brew design radios show up that will
>> demodulate and lock to the new data format. There is plenty of info on the
>> transmit format. The demodulation approach is not crazy hard. That said,
>> there’s still a lot of work to get a receiver running.  
> Has anybody looked into a software approach?  What sort of front end would 
> you want?
> -- 
> These are my opinions.  I hate spam.
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