I begin to construct a FM receiver using limesdr-usb.
Now, a .grc file can been run. But I found that I’m not quite sure how to set appropriate parameter values (RF gain, IF gain, BB gain, Transition Width and so on) for a FM receiver.
I’ve tested a lot of values. There are usually heavy noises in the output. It is strange that the output is not as good as the RTL-SDR’s output (with the same gain value, as show in the above fig).
By the way, there is an interesting phenomenon. Every time I touching the receiving antenna, the noise decreased.
Without touching the receiving antenna: (there is a FM music station at 97.4M, but i can’t hear the music)
Touching the receiving antenna: (the station’s signal appears in the frequency spectrum, and I can hear music)