cannot change frequency

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bclay
Posts: 4
Joined: Wed Aug 12, 2020 2:55 pm

cannot change frequency

Post by bclay » Wed Aug 12, 2020 3:18 pm

I am using the rtlsdr library on windows 10 with Visual studio to capture and demodulate FM radio stations. When I start my application it works on the initial frequency that I specify. I cannot change the frequency using rtlsdr_set_center_freq or retune. . Sometime there is no error and the frequency changes to some unknown frequency and I get static other times I get a -9 error code.

rtlsdr_get_center_freq shows the correct frequency after making the change.

When I start the app and let it fully initialize to get the valid audio then call rtlsdr_get_center_freq it shows a frequncy that is 384000 lower than the actual frequency.


I am using the rtl_fm example as my starting/ learning point.

Any thoughts or suggestions would be greatly appreciated

Please let my know if there is a better place to ask the question.

bclay
Posts: 4
Joined: Wed Aug 12, 2020 2:55 pm

Re: cannot change frequency

Post by bclay » Wed Aug 12, 2020 4:54 pm

As a follow up to my previous message I found that I could get the desire frequency by subtracting 384000 from the desired frequency when I call rtlsdr_set_center_freq.

I have only tried FM at this point

Other things to note;
bandwidth = 185000
sample rate 192000
resample rate 48000

Bruce

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