[time-nuts] wtd: WWVB info

[Bob Camp]

Hi

Quick summary:

WWVB changed the format of their transmissions. They now have a phase modulation 
component in the signal. That *eventually* will let people make a better chip to demodulate
the time info string (and to get more info out of it). So far the new chips have not been spotted
for sale to “normal people”.

The older AM chips still work (as do the clocks and watches). Most outfits have (apparently) cut
back on the older chips. One might guess they don’t want the inventory when the new ones hit the 
market. 

The phase modulation did a number on the old phase tracking “frequency standard” receivers. There
are posts in the archives describing work arounds for these devices. 

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. 

One offshoot of the whole switchover is that the people who *were* selling antennas pre-made for 
WWVB seem to have dropped stock just like the chip guys. That sort of drives you to both home 
brew an antenna and a receiver at the same time. 

Much of this is just the nature of “so many projects / so little time”. Some of it is the very normal 
“let’s see what the chip does” wait and see.

Bob

> On Aug 4, 2015, at 6:43 PM, Donald <donvukovic at gmail.com> wrote:
> 
> I have been looking into WWVB receivers.
> 
> I see that the sources I had purchased from a few years ago are no longer available(in the US).
> 
> I see that the format of the WWVB signal has changed a little as well.
> 
> Has NIST done something to not allow chip manufactures to make new chips/modules ?
> Is there any reason why we (in the US) are not allowed to buy these chips/modules any longer ?
> I did get a WWVB receiver out of the UK recently.
> 
> Does anyone have a schematic for building a simple WWVB receiver ?
> 
> Any information would be grateful.
> 
> - Don
> 
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