RadioBanter - View Single Post

Michael Black[_2_] · December 4th 12, 10:17 PM posted to rec.radio.shortwave

On Tue, 4 Dec 2012, wrote:

Very much so. WWV +CHU+ several others are still broadcasting around the
clock. What about GPS signals? They must be extremely
accurate,considering how many uses this service provides worlwide.

I think that's where a lot of it in non-hobby circles (and for peole who
wnat accuracy for its own sake, like those participating in the ARRL
Frequency Measuring Tests, if they still have those) has gone.

After I posted, I got curious, and the phase modulation on WWVB, while in
testing for a while, only became standard at the end of the October. But
in doing a search, I found one company that made frequency standards that
locked to WWVB, and it posted a warning, yet admits that since they
haven't made any of those in some time, GPS-based frequency standards
being the new route, the issue is less relevant.

Someone else, who had a home made WWVB receiver and crystal oscillator
locked to it, he mentions adding a modification where he doubles the
frequency of the amplified WWVB signal and then compares that with the old
reference now doubled, and it works fine. I can see that, it's
reminiscenet of a wave of DSB adapters in the ham magazines in the
seventies, where they fed the incoming signal into a 2X multiplier and
then divided that down by 2, which took out any problems, and the signal
divided by 2 was the "bfo".

Michael