Hi,

As apparently WWV doesn't transmit up that high in freq., what are some
good "freq. standard" signals to use for calibration in the vhf/uhf ranges ?

Thanks,
Bob

On Saturday, December 1, 2012 7:02:26 AM UTC-5, Bob wrote:
Hi,



As apparently WWV doesn't transmit up that high in freq., what are some

good "freq. standard" signals to use for calibration in the vhf/uhf ranges ?



Thanks,

Bob

Don't think there are ANY time/frequency standards transmitted above 30 MHz. Need more info on this subject...

On Sat, 01 Dec 2012 07:02:26 -0500, Bob wrote:

Hi,

As apparently WWV doesn't transmit up that high in freq., what are some
good "freq. standard" signals to use for calibration in the vhf/uhf ranges ?

Thanks,
Bob

What could be used as frequency standard "plucked from VHF" is the TV line
frequency.
I'm not sure if like in Europe, all TV stations in the US would be equally
useful but if you enter this search string in Google
-----
"Calibration of high precision oscillators using the TV line frequency as a
frequency standard"
-----
you get several links that suggest it might be the case.

Jan

On Sunday, December 2, 2012 10:13:50 PM UTC-5, Arid ace wrote:
On Sat, 01 Dec 2012 07:02:26 -0500, Bob wrote:



Hi,



As apparently WWV doesn't transmit up that high in freq., what are some

good "freq. standard" signals to use for calibration in the vhf/uhf ranges ?



Thanks,

Bob



What could be used as frequency standard "plucked from VHF" is the TV line

frequency.

I'm not sure if like in Europe, all TV stations in the US would be equally

useful but if you enter this search string in Google

-----

"Calibration of high precision oscillators using the TV line frequency as a

frequency standard"

-----

you get several links that suggest it might be the case.



Jan

During the analog TV days maybe it was possible, but not now. I doubt if it could be done now at all...at least in the US. Best frequency standards are at low frequencies,such as 60KHz or even lower.

On Sun, 2 Dec 2012 23:07:55 -0800 (PST), wrote:

On Sunday, December 2, 2012 10:13:50 PM UTC-5, Arid ace wrote:
On Sat, 01 Dec 2012 07:02:26 -0500, Bob wrote:



Hi,



As apparently WWV doesn't transmit up that high in freq., what are some

good "freq. standard" signals to use for calibration in the vhf/uhf ranges ?



Thanks,

Bob



What could be used as frequency standard "plucked from VHF" is the TV line

frequency.

I'm not sure if like in Europe, all TV stations in the US would be equally

useful but if you enter this search string in Google

-----

"Calibration of high precision oscillators using the TV line frequency as a

frequency standard"

-----

you get several links that suggest it might be the case.



Jan

During the analog TV days maybe it was possible, but not now. I doubt if it could be done now at all...at least in the US. Best frequency standards are at low frequencies,such as 60KHz or even lower.

As far as I can remember, the time limit to end all analogue TV transmissions in
the US is somewhere in 2015 but if none are left already it's a pity.
However WWVB at 60 KHz now is modulated in phase just like happened with many
stations in Europe so you can forget to lock a 10MHz VCXO to the WWVB carrier,
to measure the drift of any XTO, even oven controlled ones. I looked up
available time & frequency stations and unless living close enough to Europe, no
luck: http://ac6v.com/standard.htm

On Monday, December 3, 2012 8:58:55 PM UTC-5, Arid ace wrote:
On Sun, 2 Dec 2012 23:07:55 -0800 (PST), wrote:



On Sunday, December 2, 2012 10:13:50 PM UTC-5, Arid ace wrote:

On Sat, 01 Dec 2012 07:02:26 -0500, Bob wrote:







Hi,







As apparently WWV doesn't transmit up that high in freq., what are some



good "freq. standard" signals to use for calibration in the vhf/uhf ranges ?







Thanks,



Bob







What could be used as frequency standard "plucked from VHF" is the TV line



frequency.



I'm not sure if like in Europe, all TV stations in the US would be equally



useful but if you enter this search string in Google



-----



"Calibration of high precision oscillators using the TV line frequency as a



frequency standard"



-----



you get several links that suggest it might be the case.







Jan



During the analog TV days maybe it was possible, but not now. I doubt if it could be done now at all...at least in the US. Best frequency standards are at low frequencies,such as 60KHz or even lower.



As far as I can remember, the time limit to end all analogue TV transmissions in

the US is somewhere in 2015 but if none are left already it's a pity.

However WWVB at 60 KHz now is modulated in phase just like happened with many

stations in Europe so you can forget to lock a 10MHz VCXO to the WWVB carrier,

to measure the drift of any XTO, even oven controlled ones. I looked up

available time & frequency stations and unless living close enough to Europe, no

luck: http://ac6v.com/standard.htm

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.

On Mon, 3 Dec 2012, 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 problem with CHU is that it's not on an exact MHz frequency, so you
won't be able to adjust your 100KHz calibrator to that

I suppose it matters less now since you can easily divide 10MHz or 100KHz
down to 10KHz that will have a harmonic on CHU's frequencies, but it used
to be a big issue, and people who rely on 100KHz calibrators are likely
those unwilling to mod the receiver to get 10KHz.

But of course, if you're using a 100KHz calibrator, some phase modulation
isn't likely to be a problem.

Wait a minute. I WWV and WWVH have phase modulation (excrpt
whatever comes from propagation), it's WWVB that was mentioned. For a lot
of purposes, WWV is good enough, and on exact multiples of 1 MHz. The
issue is that due to propagation, it comes and goes, and can pick up
distortion along the way. But for those who were beating their 100KHz or
such calibrators against the carrier, it was good enough. The ability to
beat absolutely was hindered by the frequecy response of the receiver
(which made it harder to hear the really low beats) and once the beat is
really slow, it takes time to figure out whether you are too fast or too
slow.

Which is why WWVB was seen as the frequency standard ifyou needed
something better. If you could receiver the signal, you'd have a reliable
frequency standard, since it was groundwave (not bouncing off the
ionosphere where other issues come in). For a long time, WWVB was only a
frequency standard, initially that's all it was, then of course the
decoders to get the time took up so much circuitry that you wouldn't see
clocks that sync'ed up except in the lab. It's only the last ten or so
years where you could cheaply get "atomic clocks" and the time became
important. (And despite the low frequencies, WWVB was used because the
signal was always there, unlike WWV where the signal would fade. The
"World's Most Accurate Clock" from Heathkit used WWV, but apparently
adjusted the internal clock so it even kept good accuracy when WWV was not
receivable.)

Technically with the right receiver, you could get a 60KHz frequency out
of a WWVB receiver that was really accurate, while trying that with WWV
would fail due to fading and such. No transfer oscillator need, that
100KHz calibrator, though 60KHz isn't too useful a frequency reference in
itself.

The phase modulation on WWVB is recent, like sometime this fall. It
reflects the demand for all those "atomic clocks" since it's a secondary
method of sending the time on the carrier. Just like FM is noise-free
because you can put limiters in, the same with phase modulation, and in
plces that are at the farther edges of WWVB's pattern, phase modulation
would be more distinct since it won't be confused by interference from
other things like switching supplies that are generating "am noise".

I guess they've decided that "atomic clocks" in every household are more
important than a frequency standard, and at least nowadays there are other
methods to get accurate frequency, though less so for the hobbyist.

Let's not forget all those ads in the magazines for Hammarlund recievers
where crystal manufacturers and broadcast station engineers would plug the
receivers for profeesional use. Up until a certain time, WWV and WWVB was
used by a lot more people as a frequency standard (and WWVB for those who
needed something more), and they'd use off the shelf shortwave receivers
for that.

Then it become possible to get an expensive but still within reach Cesium
standard. Who can forget that wave of articles in the seventies about
getting a frequency standard from the color subcarrier frequency in color
tv? It wa accurate because it was set by the cesium standard at the
network. ANd then it soon faded because local stations started getting
their own cesium standards, and they weren't necessarily calibrated to the
extent of the ones at the network. They stopped using the network
standard. I may have garbled this, but there wa a point when it became
possible to get some standard that was better than a crystal oscillator
but wasn't as absolute as the atomic clock at the time stations.

The point is that the time stations became less important with time. Yes,
they are still fun and useful for the hobbyist, and WWVB is certainly
getting much more use via all those home "atomic clocks" than when it was
"merely' a frequency standard, but professional needs are being met
other ways (an indeed, professional needs often need something better
now).

Wikipedia says that there will be no phase modulation of WWVB for a
period each day, at 7 and 1900 UTC, it says for 30 minutes but it's not
clear if that's each time or 15 minutes each time. So you have some time
with an accurate frequency source, but not something that can be locked
too constantly.


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 12/01/2012 04:02 AM, Bob wrote:
Hi,

As apparently WWV doesn't transmit up that high in freq., what are some
good "freq. standard" signals to use for calibration in the vhf/uhf
ranges ?

Thanks,
Bob

Some High-end GPS receivers have a 10Mhz output. Or you can build your own.

http://www.rt66.com/~shera/index_fs.htm

http://www.ese-web.com/110.htm

On 12/04/2012 07:00 AM, dave wrote:
On 12/01/2012 04:02 AM, Bob wrote:
Hi,

As apparently WWV doesn't transmit up that high in freq., what are some
good "freq. standard" signals to use for calibration in the vhf/uhf
ranges ?

Thanks,
Bob

Some High-end GPS receivers have a 10Mhz output. Or you can build your own.

http://www.rt66.com/~shera/index_fs.htm

http://www.ese-web.com/110.htm

http://a-aengineering.com/gps.htm