Signal-processing (morse code decoding) with Android application

I made test application in Delphi that beeps morse code using Windows API Beep function. Then made an application in Android that stores this morse code in WAV file. Now I want Android application to decode the morse code. Is there some tutorials for sound processing or can somebody post some simple code (think there's no simplicity here) for an example? Or maybe steps that I need to do to get it work?

I also downloaded the JTransforms and jfttw libraries but don't really know where to 开发者_JAVA技巧start.

Regards, evilone

An FFT is overkill for this - you can just use a simple Goertzel filter to isolate the morse code from background noise, then decode the output of this.

I think an older issues of QST magazine had an article on DSP for Morse/CW decoding several years back. Might want to try and search their archives.

Basically, you need DSP code to determine whether or not a tone is present at any given point in time, and an estimate of the onset and off-time of each tone. Then scale the duration of each tone and the gap times between the tones for the expected code speed, and compare against a table of timings for each Morse code letter to estimate the probability of each or any letter being present.

In the simplest case, you might have a dot-dash-space decision tree. In severe noise and fading plus highly personalized fist/timing you might need some sophisticated statistical and/or adaptive audio pattern matching techniques for decent results.