I'm a beginner in radio demodulation, and several days can't solve my problem. The problem is to get bit stream from known frequency. I made I C# application that gets the data in real time from FunCube dongle and applies FFT. But what to do next - it is a puzzle for me. The final goal is to detect narrow-band signal on a known frequency and get the bit stream from it. I've already read different books on DSP but I'm at an impasse. So, the question is what to read, where to go, maybe any algorithms.