Xerbo 69a43e8237 | 4 lat temu | |
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.gitignore | 4 lat temu | |
LICENSE | 4 lat temu | |
Makefile | 4 lat temu | |
README.md | 4 lat temu | |
color.c | 4 lat temu | |
common.h | 4 lat temu | |
dsp.c | 4 lat temu | |
filter.c | 4 lat temu | |
filter.h | 4 lat temu | |
filtercoeff.h | 4 lat temu | |
image.c | 4 lat temu | |
main.c | 4 lat temu | |
median.c | 4 lat temu | |
offsets.h | 4 lat temu | |
pngio.c | 4 lat temu | |
reg.c | 4 lat temu | |
satcal.h | 4 lat temu | |
textlogo.png | 5 lat temu |
Copyright (c) 2004-2009 Thierry Leconte (F4DWV), Xerbo (xerbo@protonmail.com) 2019-2020
Aptdec is an FOSS program that decodes images transmitted by NOAA weather satellites. These satellites transmit continuously (among other things), medium resolution (1px/4km) images of the earth on 137 MHz.
These transmissions could be easily received with an simple antenna and cheap SDR. Then the transmission can easily be decoded in narrow band FM mode.
Aptdec can convert these audio files into png
images.
For each audio file up to 6 images can be generated:
The input audio file must be mono with a sample rate in the range of 4160-62400 Hz, lower samples rates will process faster.
Aptdec uses libsndfile
to read the input audio, so any format supported by libsndfile
may be used (however it has only tested with .wav
files).
Aptdec is portable since it is written in standard C.
It has successfully compiled and ran on Debian with both gcc
, clang
and tcc
and will most likely work on any Unix platform.
Just edit the Makefile and run make
(no configure script as of right now).
Aptdec uses libsndfile
, libpng
and libm
.
The snd.h
and png.h
headers must be present on your system.
If they are not on standard path, edit the include path in the Makefile.
To compile
make
To run without installing
./aptdec [options] audio files...
To install
sudo make install
To run once installed
aptdec [options] audio files...
To uninstall
sudo make uninstall
-i [r|a|b|c|t|m]
Output image type
Raw (r), Channel A (a), Channel B (b), False Color (c), Temperature (t) or MCIR (m)
Default: "ab"
-d <dir>
Images destination directory (optional)
Default: Current directory
-s [15|16|17|18|19]
Satellite number
For temperature calibration
Default: "19"
-e [r|a|b|c|t|m]
Effects
Histogram equalise (h), Crop Telemetry (t), Denoise (d), Precipitation (p) or Linear equalise (l)
Defaults: off
-m <file>
Map file generated by wxmap
-o <filename>
Output image filename
-r
Realtime decode. When decoding in realtime it is highly recommended to choose a plain raw image.
Generated images are outputted in PNG and are 24 bit RGB for all image types apart from pure greyscale images.
Image names are audiofile-x.png
, where x
is:
r
for raw images1
, 2
, 3A
, 3B
, 4
, 5
) for channel A|B imagesc
for false colort
for temperature calibrated imagesm
for MCIR imagesCurrently there are 6 available effects:
t
for crop telemetry, off by default, only has effects on raw imagesh
for histogram equalise, stretch the colors in the image to black and whited
for a median denoise filterp
for a precipitation overlayf
to flip the image (for southbound passes)l
to linearly equalise the image (recommended for falsecolor images)aptdec -d images -i ab *.wav
This will process all .wav
files in the current directory, generate calibrated channel A and B images and put them in the images
directory.
aptdec -e dh -i b audio.wav
Decode audio.wav
with denoise and histogram equalization and save it into the current directory.
As of recently a realtime output was added allowing realtime decoding of images.
mkfifo /tmp/aptaudio
aptdec /tmp/aptaudio
sox -t pulseaudio alsa_output.pci-0000_00_1b.0.analog-stereo.monitor -c 1 -t wav /tmp/aptaudio
Perform a realtime decode with the audio being played out of alsa_output.pci-0000_00_1b.0.analog
.
https://noaasis.noaa.gov/NOAASIS/pubs/Users_Guide-Building_Receive_Stations_March_2009.pdf
https://web.archive.org/web/20141220021557/https://www.ncdc.noaa.gov/oa/pod-guide/ncdc/docs/klm/tables.htm
See LICENSE.