HALF SDR

when i joined the hearsat comuinty, i quickly realized that just listening the signals is not enough. so i made a converter to see the signals with a FFT program on the PC.
the half SDR is just a simple down converter. it converts the 10.7 MHz IF output of my VR-5000 into a 20 KHz wide audio signal. the local oscillator operates on 10.690 MHz, so the middle (10.7 MHz) is at 10 KHz audio frequency. the x-tal filter is needed to suppress the lower sideband.
the evaluation board
data bursts from a UHF satellite
this is FHSS, a fast frequency hopping mode
the pix are taken from " baudline ", a free FFT program for Linux, freeBSD and Solaris. baudline works with mono or stereo sources, can handle several soundcards and it also takes I/Q signals from a normal SDR. many parameters are user adjustable and you can equalise the frequency responce of the receiver. a good piece of software. www.baudline.com
the VR-5000 has a 200 KHz wide IF-out. to see the whole bandwith i will build a real SDR. but this simple hardware was worth to test, it opened my eyes.