Frequency Accuracy

[Michael Barnes]

I installed gqrz per the webpage http://gqrx.dk/download/install-ubuntu. Everything went fine. Then I launched gqrx and started looking for signals. My first attempt was the local NOAA weather broadcast at 162.475. Nothing. But, looking at the display, I see adjacent signals. Tuning down, I find the weather at an indicated frequency of 162.452. Looking at other signals for NOAA, ham, and public safety, I'm finding a frequency error of 15-30 kHz. I then installed Dump1090 to receive ADS-B broadcasts from aircraft at 1090 MHz. Even though I closed gqrx, it still kept a grip on my SDR dongle. I had to reboot the computer to get gqrx to release and allow Dump1090 to use the dongle. It ran fine and accurately received at 1090 MHz and displayed flight data.

So, is there some way to calibrate gqrx so I can accurately determine what frequency I am looking at, or to enter a frequency and actually capture that channel and listen to it?

Thanks,

Michael WA7SKG

[Andrew Rich]

Ok which sdr dongle 

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[Andrew Rich]

Parts per million

PPM offset on your dongle

That's a big step well maybe not

My good dongles don't need changing

My cheap ones I have to walk on frequency

I use the fm stations on 104 MHz

Andrew 

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On 21 Aug 2017, at 4:24 pm, Michael Barnes <barnm...@gmail.com> wrote:

[Andrew Rich]

Oh 1090 MHz is several MHz wide so it does not care 

I think icao says you can be a MHz off 

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On 21 Aug 2017, at 4:24 pm, Michael Barnes <barnm...@gmail.com> wrote:

[Andrew Rich]

http://gqrx.dk/doc/practical-tricks-and-tips

Sent from my iPhone

On 21 Aug 2017, at 4:24 pm, Michael Barnes <barnm...@gmail.com> wrote: