Time and Frequency References
 

How important are time and frequency references to amateur radio
operators? I've been working on a radio controlled clock design that
would be capable of generating a 32.768 kHz, 60 kHz, 240 kHz, 1 MHz and
10 MHz frequency references in addition to providing the time and date.
Initially it would be capable of receiving the 60 kHz transmissions of
WWVB and MSF. With minor tweaks other stations could be received.

Would this be useful to others?

--

Rick

Time and Frequency References
 

rickman wrote:
How important are time and frequency references to amateur radio
operators? I've been working on a radio controlled clock design that
would be capable of generating a 32.768 kHz, 60 kHz, 240 kHz, 1 MHz and
10 MHz frequency references in addition to providing the time and date.
Initially it would be capable of receiving the 60 kHz transmissions of
WWVB and MSF. With minor tweaks other stations could be received.

Would this be useful to others?

We use GPSDOs in our co-channel diversity repeater.
The signals we require a 10 MHz and 1PPS.
It would be convenient when modules for arbitrary frequencies could
be inserted (like 10.240 MHz). Our GPSDO allows only evenly divisible
fractions of 10 MHz (like 5, 2, 1 MHz) as auxilliary outputs.

Another thing is that the short-term accuracy is not optimal.
These references "wander around" the correct frequency.

Time and Frequency References
 

In article , rickman
wrote:

How important are time and frequency references to amateur radio
operators? I've been working on a radio controlled clock design that
would be capable of generating a 32.768 kHz, 60 kHz, 240 kHz, 1 MHz and
10 MHz frequency references in addition to providing the time and date.
Initially it would be capable of receiving the 60 kHz transmissions of
WWVB and MSF. With minor tweaks other stations could be received.

Would this be useful to others?

Rick-

Anyone who would use your frequency reference might be interested if it
is less expensive than other methods. I believe GPS-trained references
are available. I have a rubidium-controlled oscillator I bought on
E-Bay.

For routine Ham Radio use, I depend on 20 MHz WWV to periodically check
the calibration of my transceivers. By switching between CW and CW-R, I
can adjust the equipment so the CW pitch is the same for both. I am
confident that I can adjust a radio so it is within one Hz at 20 MHz.

That puts me within 0.05 parts per million, at least at the moment I
make the adjustment. I expect the equipment to drift over time and
temperature.

Most Amateur Radio Operators do not worry that much about frequency.
Some of the people I talk to on higher frequencies, drift over a few
minutes time. Nobody seems to care!

Fred
K4DII

Time and Frequency References
 

On 18/04/2016 15:39, rickman wrote:
How important are time and frequency references to amateur radio
operators? I've been working on a radio controlled clock design that
would be capable of generating a 32.768 kHz, 60 kHz, 240 kHz, 1 MHz and
10 MHz frequency references in addition to providing the time and date.
Initially it would be capable of receiving the 60 kHz transmissions of
WWVB and MSF. With minor tweaks other stations could be received.

Would this be useful to others?

A good frequency standard has many uses for the radio amateur. There are
many designs around many using GPS as the reference source as well as
MSF and the like.

--
Peter Crosland

Reply address is valid

Time and Frequency References
 

On 18/04/16 15:39, rickman wrote:
How important are time and frequency references to amateur radio
operators? I've been working on a radio controlled clock design that
would be capable of generating a 32.768 kHz, 60 kHz, 240 kHz, 1 MHz and
10 MHz frequency references in addition to providing the time and date.
Initially it would be capable of receiving the 60 kHz transmissions of
WWVB and MSF. With minor tweaks other stations could be received.

Would this be useful to others?


Anyone who wants high accuracy off air time and frequency standards
would use GPS these days. Even that is almost two decade old technology
in amateur radio usage: http://www.tapr.org/kits_tac2.html

Also note that cross-posting to a moderated newsgroup will delay the
posting in the unmoderated group and cross-posting to two moderated
groups will, almost certainly, stop it being distributed at all.

Time and Frequency References
 

In article ,
says...



Anyone who would use your frequency reference might be interested if it
is less expensive than other methods. I believe GPS-trained references
are available. I have a rubidium-controlled oscillator I bought on
E-Bay.

For routine Ham Radio use, I depend on 20 MHz WWV to periodically check
the calibration of my transceivers. By switching between CW and CW-R, I
can adjust the equipment so the CW pitch is the same for both. I am
confident that I can adjust a radio so it is within one Hz at 20 MHz.

That puts me within 0.05 parts per million, at least at the moment I
make the adjustment. I expect the equipment to drift over time and
temperature.

Most Amateur Radio Operators do not worry that much about frequency.
Some of the people I talk to on higher frequencies, drift over a few
minutes time. Nobody seems to care!


I just got caled out 2 nights ago for being off frequency by 50 HZ on 10
meters. Was using an Icom 706IIG.

I don't worry about things like that. As long as I am in the band and
not drifting all over the place is good enough for me. I could
calibrate it using one of the service monitors I have. Not sure how far
they are off, but they count to the last cycle of WWV at 20 MHz and will
sometimes blink to 19.99 and all 9s.

Friend that I talk to about every day usually jumps around 50 to 100 Hz
on 75 meters with a Collins and an old Yeasu.
I don't worry about that, just rit him in.

I think a low cost GPS or one of the Atomic standards would be the way
to go if the price could be low enough.

Time and Frequency References
 

On 4/18/2016 11:29 AM, Rob wrote:
rickman wrote:
How important are time and frequency references to amateur radio
operators? I've been working on a radio controlled clock design that
would be capable of generating a 32.768 kHz, 60 kHz, 240 kHz, 1 MHz and
10 MHz frequency references in addition to providing the time and date.
Initially it would be capable of receiving the 60 kHz transmissions of
WWVB and MSF. With minor tweaks other stations could be received.

Would this be useful to others?

We use GPSDOs in our co-channel diversity repeater.
The signals we require a 10 MHz and 1PPS.
It would be convenient when modules for arbitrary frequencies could
be inserted (like 10.240 MHz). Our GPSDO allows only evenly divisible
fractions of 10 MHz (like 5, 2, 1 MHz) as auxilliary outputs.

Another thing is that the short-term accuracy is not optimal.
These references "wander around" the correct frequency.

Short term accuracy is what costs real bucks. You need a very stable
VCTCXO or ovenized VCXO. How much accuracy are you seeing and how much
would you like?

--

Rick

Time and Frequency References
 

rickman wrote:
On 4/18/2016 11:29 AM, Rob wrote:
rickman wrote:
How important are time and frequency references to amateur radio
operators? I've been working on a radio controlled clock design that
would be capable of generating a 32.768 kHz, 60 kHz, 240 kHz, 1 MHz and
10 MHz frequency references in addition to providing the time and date.
Initially it would be capable of receiving the 60 kHz transmissions of
WWVB and MSF. With minor tweaks other stations could be received.

Would this be useful to others?

We use GPSDOs in our co-channel diversity repeater.
The signals we require a 10 MHz and 1PPS.
It would be convenient when modules for arbitrary frequencies could
be inserted (like 10.240 MHz). Our GPSDO allows only evenly divisible
fractions of 10 MHz (like 5, 2, 1 MHz) as auxilliary outputs.

Another thing is that the short-term accuracy is not optimal.
These references "wander around" the correct frequency.

Short term accuracy is what costs real bucks. You need a very stable
VCTCXO or ovenized VCXO. How much accuracy are you seeing and how much
would you like?

We have ridiculous requirements :-)
We already have such things but it is not enough.
Probably we should try a rubidium GPSDO.

The 10 MHz is used to lock a 430 MHz transmitter and it should remain
in phase with another one. It is preferable that the frequency remains
stable if a bit off.

What happens now is that the DAC in the GPSDO steps up and down every
couple of seconds, and the oscillators wobble around the correct frequency
in the 1E-9 area (with of course an average that is very close, more like
1E-11), and this results in funny interference patterns. What is
happening is clear when you put the 10 MHz outputs of two independent
boxes on the scope in X-Y mode.

Time and Frequency References
 

On 4/19/2016 4:10 AM, Rob wrote:
rickman wrote:
On 4/18/2016 11:29 AM, Rob wrote:
rickman wrote:
How important are time and frequency references to amateur radio
operators? I've been working on a radio controlled clock design that
would be capable of generating a 32.768 kHz, 60 kHz, 240 kHz, 1 MHz and
10 MHz frequency references in addition to providing the time and date.
Initially it would be capable of receiving the 60 kHz transmissions of
WWVB and MSF. With minor tweaks other stations could be received.

Would this be useful to others?

We use GPSDOs in our co-channel diversity repeater.
The signals we require a 10 MHz and 1PPS.
It would be convenient when modules for arbitrary frequencies could
be inserted (like 10.240 MHz). Our GPSDO allows only evenly divisible
fractions of 10 MHz (like 5, 2, 1 MHz) as auxilliary outputs.

Another thing is that the short-term accuracy is not optimal.
These references "wander around" the correct frequency.

Short term accuracy is what costs real bucks. You need a very stable
VCTCXO or ovenized VCXO. How much accuracy are you seeing and how much
would you like?

We have ridiculous requirements :-)
We already have such things but it is not enough.
Probably we should try a rubidium GPSDO.

The 10 MHz is used to lock a 430 MHz transmitter and it should remain
in phase with another one. It is preferable that the frequency remains
stable if a bit off.

What happens now is that the DAC in the GPSDO steps up and down every
couple of seconds, and the oscillators wobble around the correct frequency
in the 1E-9 area (with of course an average that is very close, more like
1E-11), and this results in funny interference patterns. What is
happening is clear when you put the 10 MHz outputs of two independent
boxes on the scope in X-Y mode.

I don't know what they are using for an oscillator, but if you have
control over it, can you reduce the corner frequency of the LPF on the
control loop? It sounds like the control loop is hunting to me. But at
10-9 I suppose it could be ambient thermal drift too. Yes, I think a
rubidium GPSDO would do the job.

I remember a couple/three years ago Symmetricom came out with a chip
scale atomic clock that can sync to a 1 pps. "Two orders of magnitude
better accuracy than oven-controlled crystal oscillators". Only $1,000.
Might do the job. They likely package this in a box level product
that will do what you want. Check out this one...

http://www.microsemi.com/products/ti...-2750#overview

They were bought by Microsemi it seems.

--

Rick

Time and Frequency References
 

rickman wrote:
What happens now is that the DAC in the GPSDO steps up and down every
couple of seconds, and the oscillators wobble around the correct frequency
in the 1E-9 area (with of course an average that is very close, more like
1E-11), and this results in funny interference patterns. What is
happening is clear when you put the 10 MHz outputs of two independent
boxes on the scope in X-Y mode.

I don't know what they are using for an oscillator, but if you have
control over it, can you reduce the corner frequency of the LPF on the
control loop? It sounds like the control loop is hunting to me. But at
10-9 I suppose it could be ambient thermal drift too. Yes, I think a
rubidium GPSDO would do the job.

I think the problem is that our GPSDO has a 16-bit DAC and it is
dithering the digital value to obtain the correct frequency. So when
the correct DAC value would be 32000.2 it will do 32000 for 8 seconds
then 32001 for 2 seconds, obtaining a long-term average that is quite
good, but a wobble with 10-second period as well.

These are old Datum 9390 units, we also have some Trimble Thunderbolts
that should be better.

I remember a couple/three years ago Symmetricom came out with a chip
scale atomic clock that can sync to a 1 pps. "Two orders of magnitude
better accuracy than oven-controlled crystal oscillators". Only $1,000.
Might do the job. They likely package this in a box level product
that will do what you want. Check out this one...

I would prefer a box that works from GPS and outputs the 1PPS.
The Datum and Trimble are in that category.

http://www.microsemi.com/products/ti...-2750#overview

They were bought by Microsemi it seems.

I Have seen and considered these before. That is indeed a GPS referenced
rubidium standard. Of course we always prefer stuff that is either
cheap or available as surplus (like the Datum and Trimble) :-)