okay, i didnt post very often in the last time – sorry for that ;)
but here some new screenshots showing my java-tool decoding the police radio frequency.
On the right side you see the connected processing modules like a squelch filter based on FFT, some AM/FM demodulator, a FIR filter to remove unwanted noise and a sound output and WAV writer to record the demodulated audio into a WAV or MP3-file.
On the left side, there’s the control panel for that USB receiver. There i can set the frequency, filter width and some AGC parameters. It also allows scanning more frequencies and stopping at one, as long it has a strong signal level. (you perhaps know this function from some police radio scanners)
Shows a simple FFT of some police radio signals IIRC.
This image shows a graphical editor for the open source tool GNURadio. Its similar to the tool i built, but just has 20 times more functionality ;)
On that image i built a stereo FM decoder (its not that easy!) which reads from a file and outputs the signal to the sound device.
After some screens like this one:
I was able to make a GNURadio “node” which reads from my shared mem areas (using my DLL). That means, i was able to integrate GNURadio (e.g. the FM Stereo decoder) into a running instance of my ShmemManager and had a live stereo radio.
So instead of the File Source node in GNURadio i had a SHMEM Source. Changing the radio frequency in my Java tool immediately (well…. with 2 sec delay… ;) ) gave me the new radio station on the soundcard.
In fact some very cool stuff. But that stuff wont be released, since it only useful if you have that USB receiver a friend built. Sorry for that ;)