Where can I find a good correction frequency?

[vini_i]

I'm new to SDR. I live in Cuyahoga Falls, Summit County, Ohio. I would like to adjust the correction factor in my two SDRs. From what I've seen, I need a very narrow signal at a known frequency to adjust the correction factor for my SDRs. I have no idea where to find a nice narrow signal.

Would someone point me to a signal I can use for correction adjustment?

 

[boatbod]

I'm new to SDR. I live in Cuyahoga Falls, Summit County, Ohio. I would like to adjust the correction factor in my two SDRs. From what I've seen, I need a very narrow signal at a known frequency to adjust the correction factor for my SDRs. I have no idea where to find a nice narrow signal.

Would someone point me to a signal I can use for correction adjustment?

If you have any local public service radios in your area you could tune one of their control channel freqs. They are usually only ~3khz or so wide, and if you use an application like op25 that can understand the control channel and show you the mixer & constellation plots you can dial the tuning in within 100Hz or so fairly readily. That same ppm figure should then be usable for any other application using the same dongle.

 

[n0nhp]

I am able to hear the ATIS at my local airport. By placing the rx in SSB (either upper or lower) I can zero beat the carrier. Checking the carrier at the shop I used to work at, it is as close as a calibrated service monitor can tell to being right on frequency (govt. test equipment usually gets calibrated every year so is usually pretty close).

Bruce

 

[M105]

I use SDR# and look for a local known digital control channel frequency usually in the 450-460 MHz range. Let the dongle warm up by running it for 5-10 minutes with SDR# numerically tuned to where the signal is supposed to be. Adjust the ppm in SDR# until you have the red marker at the signal peak and leave it running for a few more minutes to check for drift. Note the number. You will be close enuf fer guvment wurk.

 

[mmisk]

I like using the ATSC Pilot Frequencys

Examples:
CH 14 470.310 MHz
CH 15 476.310 MHz
CH 16 482.310 MHz
CH 17 488.310 MHz
CH 18 494.310 MHz
CH 19 500.310 MHz
CH 20 506.310 MHz
CH 21 512.310 MHz
CH 22 518.310 MHz
CH 23 524.310 MHz
CH 24 530.310 MHz

Each pilot frequency is 6mhz apart

 

[nd5y]

I like using the ATSC Pilot Frequencys

Examples:
CH 14 470.310 MHz
CH 15 476.310 MHz
CH 16 482.310 MHz
CH 17 488.310 MHz
CH 18 494.310 MHz
CH 19 500.310 MHz
CH 20 506.310 MHz
CH 21 512.310 MHz
CH 22 518.310 MHz
CH 23 524.310 MHz
CH 24 530.310 MHz

Each pilot frequency is 6mhz apart

Be careful with that. Some TV stations are offset and the pilot signal isn't exactly 310 kHz above the lower band edge.

 

[nowires]

It looks like to me I've used kalibrate, but using gqrx I get one ppm for wx/noaa and m36. While tuning in p25 I end up on the low cut of the center frequency. I have to lower ppm to get p25 a difference from what I use on wx/noaa. Maybe because p25 is 12.5/6.25? Not sure why there is a ppm shift on p25 that isn't on other freqs. Possibly on 1090MHz also, don't have a strong enough signal to figure out whether I'm actually on the center there either.

 

[mmisk]

Be careful with that. Some TV stations are offset and the pilot signal isn't exactly 310 kHz above the lower band edge.

Yes, I like to check several pilot signals so far they are all right on in my area.
I bought the latest SDR devices and they are rock stable. Sure is nice to have these.
My old ones needed a warm up period and would drift.