Do a google search on "satellite_seminar.pdf." There will be two
sites that come up. Click on the princeton site which will download
the pdf document. Look on page 16 of that pdf document for an AM
demodulation algorithm. Look on page 17 for a JAVA implementation.
This algorithm works fine, because I have used it; however, you must
consider 1) the input audio signal format to be demodulated and 2) the
sample rate that you demodulate. Otherwise, your picture will look
like random garbage.
To briefly explain ...
1) I used an 8 bit WAV file to record the weather satellite audio
signal, so I had to subtract 127 from the WAV data before I applied
the AM demodulation algorithm.
2) each line has a visible image and an IR image. You must consider
your sample rate because you will want to toss some data; otherwise,
your image will be slanted.
After you get this working, you will probably want to use wxsat.
By the way, you really should try to understand the math!