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

On Mon, 3 Dec 2012 21:49:28 -0800 (PST), wrote:

[...]

We don't have any analog tv broadcasting since 2009 over here,in NYC. If WWV and its sisters like WWVB or WWVH cannot be used due to the phase modulation- I think the Canadian CHU still uses simple AM modulation or something very close to it.

The phase modulation used by WWVB is a bit messy. The value of 180 deg for all
data would be OK because multiplying the signal with itself would remove the
modulation. Unfortunately, the station ID uses 45 deg, see
http://en.wikipedia.org/wiki/WWVB
CHU might be the better alternative then, that the frequencies in use aren't a
multiple of 100 KHz or 1 MHz isn't a problem. With some creative calculation I
managed to lock both 153 KHz and 77.5 KHz to a 10 MHz VCXO so this case is
unlikely to be much different. 14670 and 7335 KHz would have my preference as
the first is twice the second so one receiver could easily use both signals.

Jan

On 12/05/2012 03:28 AM, Bob Dobbs wrote:


CHU no longer uses the 7335 slot but has moved to 7850,
has been for over three years now.


If anyone is still looking for a traceable frequency reference:
http://www.jrmiller.demon.co.uk/proj...std/frqstd.htm

On Wednesday, December 5, 2012 10:52:25 AM UTC-5, dave wrote:
On 12/05/2012 03:28 AM, Bob Dobbs wrote:





CHU no longer uses the 7335 slot but has moved to 7850,

has been for over three years now.





If anyone is still looking for a traceable frequency reference:

http://www.jrmiller.demon.co.uk/proj...std/frqstd.htm

Nice unit.Stable at 10E-11 part.That is MUCH better than HF transmissions and their inherent delays and fading/dropouts !

On Wed, 05 Dec 2012 03:28:44 -0800, Bob Dobbs wrote:

Arid ace wrote:
On Mon, 3 Dec 2012 21:49:28 -0800 (PST), wrote:

[...]

We don't have any analog tv broadcasting since 2009 over here,in NYC. If WWV and its sisters like WWVB or WWVH cannot be used due to the phase modulation- I think the Canadian CHU still uses simple AM modulation or something very close to it.

The phase modulation used by WWVB is a bit messy. The value of 180 deg for all
data would be OK because multiplying the signal with itself would remove the
modulation. Unfortunately, the station ID uses 45 deg, see
http://en.wikipedia.org/wiki/WWVB
CHU might be the better alternative then, that the frequencies in use aren't a
multiple of 100 KHz or 1 MHz isn't a problem. With some creative calculation I
managed to lock both 153 KHz and 77.5 KHz to a 10 MHz VCXO so this case is
unlikely to be much different. 14670 and 7335 KHz would have my preference as
the first is twice the second so one receiver could easily use both signals.

Jan

CHU no longer uses the 7335 slot but has moved to 7850,
has been for over three years now.

Thanks, I didn't know that, having used European stations for decades.
Time to buy a rubidium based frequency standard (made in China of course) then
as that's both more precise and cheaper than a GPS based solution.

On 12/05/2012 07:09 PM, Arid ace wrote:
On Wed, 05 Dec 2012 03:28:44 -0800, Bob Dobbs wrote:

CHU no longer uses the 7335 slot but has moved to 7850,
has been for over three years now.

Thanks, I didn't know that, having used European stations for decades.
Time to buy a rubidium based frequency standard (made in China of course) then
as that's both more precise and cheaper than a GPS based solution.


I doubt it's more precise than GPS, which uses several "atomic" clocks,
but cheaper it is.

http://maxmcarter.com/rubidium/index.php

On Thu, 06 Dec 2012 07:43:12 -0800, dave wrote:

On 12/05/2012 07:09 PM, Arid ace wrote:
On Wed, 05 Dec 2012 03:28:44 -0800, Bob Dobbs wrote:

CHU no longer uses the 7335 slot but has moved to 7850,
has been for over three years now.

Thanks, I didn't know that, having used European stations for decades.
Time to buy a rubidium based frequency standard (made in China of course) then
as that's both more precise and cheaper than a GPS based solution.


I doubt it's more precise than GPS, which uses several "atomic" clocks,
but cheaper it is.

http://maxmcarter.com/rubidium/index.php

Excellent article and good news that the dreaded +/- 45 deg phase shift will
disappear. As the signal here in Panama can be received as well, it means I can
use it in a design for a frequency standard adapted to a very low signal, based
on the same (rather successful) principle I used in Europe.