11m frequency reference beacon?

[brandon7861]

Discussion about clarifiers convinced me to bring up something I have wondered about for years. An 11m SSB signal reference beacon.

I don't mean a constant signal like WWV, but rather a once every 2 hours for 20 seconds type of thing. If we had a beacon locked to a GPSDO that transmits unmodulated at 27.404MHz for 20 seconds at the stroke of every other hour, people would be able to use their phones with a free audio spectrum app to watch for 1kHz while they dial their clarifiers into that signal. It would be short enough to not disrupt use of the channel, but frequent enough to catch conditions throughout the day and be useful to people without test gear. The reason I chose ch40 is because the clarifier cannot adjust the PLL error, so keeping the beacon near SSB channels makes sense.

Illegal, probably. I don't know. I think it would be very useful. Opinions?

 

[Gman]

I think its a great idea. Not only a reference signal, but band condition indicator too!

 

[brandon7861]

I wouldn't mind seeing it become a limited nationwide project where maybe 6 sites do this on different frequencies.

It would make sense to have two transmissions. One to identify, provide UTC and indicate to the person interested in aligning that conditions are available and a signal burst is coming (giving that person time to prepare, open app etc). Maybe a 2 minute delay and then the 20 second signal. It would give everyone a chance to clear the channel too.

The only limiting factor would be cooperation. Some 111 guy will probably come along 40Hz off at the same time on purpose.

 

[nomadradio]

Actually this might work better with an AM modulated tone. When you switch from AM to one sideband, you'll know you're on frequency when the tone pitch is exactly the same from AM to sideband. Much easier than trying to hear a true zero beat. That's how we set a receiver to WWV.

73

 

[brandon7861]

If someone organized the thing, did some public outreach to show support, and then petitioned the FCC to allow a little more power, would they go along with it? Is that something that is even considered by them or would the project be doomed to run on 4w?

 

[Captain Kilowatt]

With the way propagation comes in and out, I think two hours between transmissions is too long. There are LOTS of continuous beacons transmitting on the bottom of 10m. Why not just use those because if 10m is open, 11m will be.

 

[brandon7861]

With the way propagation comes in and out, I think two hours between transmissions is too long. There are LOTS of continuous beacons transmitting on the bottom of 10m. Why not just use those because if 10m is open, 11m will be.

I thought it would be better to use something close to the SSB channels. If you adjust your clarifier to a reference signal at 10m and your PLL reference oscillator is off a little, by the time you go back to ch38, its transmitting off frequency again.

The goal was to provide a simple way for everyone to get on frequency in 11m SSB territory. If the reference signal will be out of band, there is no benefit over using WWV.

 

[Captain Kilowatt]

I thought it would be better to use something close to the SSB channels. If you adjust your clarifier to a reference signal at 10m and your PLL reference oscillator is off a little, by the time you go back to ch38, its transmitting off frequency again.

The goal was to provide a simple way for everyone to get on frequency in 11m SSB territory. If the reference signal will be out of band, there is no benefit over using WWV.

What??????? If you for some unknown reason want GPS precision for frequency control, you need something other than a CB radio. I have no idea what you are intending to do and listening to something on 10m and returning to 11m in no way will make you off frequency. If you want GPS timing to accurately determine the TX intervals that is simple and has nothing to do with frequency accuracy.

 

[brandon7861]

and listening to something on 10m and returning to 11m in no way will make you off frequency.

A misaligned PLL reference crystal can cause noticeable error in channel step, so if someone used a frequency locked beacon at 10m to adjust their unlocked clarifier, the radios new found accuracy is only valid on that one channel/frequency as changing channel after that (like going back to 11m) introduces this PLL error back to the output.

It is a small error that grows the further you go, but across the 11m band alone, I have seen this error accumulate to be in excess of the alignment tolerance between ch1 and ch40. This is why, if someone wants to use such a beacon to temporarily make their radio on frequency, it is important they do so at or near the channel/frequency they intend to operate on.

This isn't providing a way to align every oscillator in a radio, it just uses one of them to compensate for the error of all of them on one channel only.

Could you clarify on 10m and then go to 11m, probably, but IMO, any peace of mind is gone at that point.

 

[Captain Kilowatt]

A misaligned PLL reference crystal can cause noticeable error in channel step, so if someone used a frequency locked beacon at 10m to adjust their unlocked clarifier, the radios new found accuracy is only valid on that one channel/frequency as changing channel after that (like going back to 11m) introduces this PLL error back to the output.

It is a small error that grows the further you go, but across the 11m band alone, I have seen this error accumulate to be in excess of the alignment tolerance between ch1 and ch40. This is why, if someone wants to use such a beacon to temporarily make their radio on frequency, it is important they do so at or near the channel/frequency they intend to operate on.

This isn't providing a way to align every oscillator in a radio, it just uses one of them to compensate for the error of all of them on one channel only.

Could you clarify on 10m and then go to 11m, probably, but IMO, any peace of mind is gone at that point.

I wasn't talking about using a 10m beacon to align anything. Why would you? It is transmitter by homemade gear most of the time or sometimes a converted CB radio to operate on 10m.The VAST majority are NOT frequency locked any more than the tolerances the gear was made with. I was talking about simply listening to the worldwide 10m beacon network that transmits in CW. You can see what parts of the world is open to your area easily. Often the beacons transmit at different power levels in steps to allow you to see how much power is required as well.

 

[nomadradio]

I have seen this error accumulate to be in excess of the alignment tolerance between ch1 and ch40.

That's caused by error in the 10.24 MHz crystal. Early 40-channel CB PLLs had a trimmer on that crystal, along with the heterodyne and carrier crystals. No 40-channel CB made since 1980 or so has a separate adjustment for that. Guess they decided that feature doesn't pay for itself.

73