aptdec/README

ATPDEC README (Thierry Leconte 2003)

DESCRIPTION
Atpdec is a open source program that decode images transmitted by POES
NOAA weather satellite serie.
These satellites transmit continuously, among other things, medium resolution images
of the earth on 137Mhz.
These transmitions could be easely received with
an inexpensive antenna and dedicated receiver.
Output from such a receiver, is an audio signal that could be recorded
into a soundfile with any soundcard.

Atpdec will convert these sounfiles into .png images.

For each soundfile up to 4 images could be generated :
1) Raw image : contains the 2 transmitted channel images  + telemetry and synchro pulses.
	Raw image is not calibrated, so it could be too dark or too light depending of
	the recording level.
2) Calibrated channel A image
3) Calibrated channel B image
4) False color image

Input soundfiles must be mono signal sampled at 11025 Hz.
Atpdec use libsnd to read soundfile, so any sound file format supported by libsnd
could be read.(Only tested with .wav file).

COMPILATION

Atpdec is written in plain standart C and must be very portable.
It was only tested on Linux Suse 8.2, but must work on any Unix platform.
Just adapt the Makefile and type make (sorry no configure). 

atpdec use libsnd, libpng and libm
snd.h and png.h header must be present on your system.
If they are not on standard path, edit the include path in the Makefile.

USAGE

atpdec [options] soundfile

-c file.png
Use a given colormap for false color generation. Default : Internal colormap.
-i [r|a|b|c]
Toggle raw (r) , channel A (a) , channel B (b) or false color (c) output.
Default : "abc"
-d directory
Optional images destination directory. Default : sounfile directory.
-s Output 8bits grayscale images for chanel A|B and raw images. Default :16bits

Generated image are in png format, 16 or 8bits greyscale for raw and channel A|B images,
24bits RVB for false color.
Image names are soundfilename-x.png, where x is :
	-r for raw images
	-satellite instrument number (1,2,3A,3B,4,5) for channel A|B images
	-c for false colors.

	
EXAMPLE
atpdec -d test -i ac 09121333.wav

Will process the 09121333.wav file and  generate channel A test/09121333-2.png and false color test/09121333-c.png image files.