RS-tracker/scan

detect radiosonde type

Files

• dft_detect.c

Compile

gcc dft_detect.c -lm -o dft_detect

Usage

./dft_detect [options] <file>
options:
     --IQ <fq>  :  IQ data input, where <fq> is the relative frequency in -0.5..0.5
     -v  :  sample count
     -c  :  continuous output
     -t <sec>  :  time limit

(input <file> can be stdin)

FM data:
./dft_detect <fm_audio.wav>

IQ data:
./dft_detect --IQ <fq> <iq_data.wav>
For IQ data (i.e. 2 channels) it is possible to read raw data (without wav header):
./dft_detect --IQ <fq> - <sr> <bs> <iq_data.raw>
where
     <sr>  :  sample rate
     <bs>=8,16,32  :  bits per (real) sample (u8, s16 or f32)

dft_detect stops, if a (potential) radiosonde signal is detected, or if a time limit is set with option -t.
With option -c detection is continued, but a time limit can be set with -t.

Output is of the form <TYPE>: <score> where the correlation score is a normalized value in -1..+1.

Examples

Ex.1

$ ./dft_detect fm_audio.wav
sample_rate: 48000
bits       : 8
channels   : 1
RS41: 0.9885

Ex.2

$ ./dft_detect -c fm_audio.wav 2>/dev/null
RS41: 0.9885
RS41: 0.9851
RS41: 0.9784
RS41: 0.9869
RS41: 0.9845
RS41: 0.9828
RS41: 0.9814
RS41: 0.9821
RS41: 0.9823
RS41: 0.9882
[...]

Ex.3

$ ./dft_detect -c -t 4 fm_audio.wav 2>/dev/null
RS41: 0.9885
RS41: 0.9851
RS41: 0.9784
RS41: 0.9869
RS41: 0.9845

Ex.4

$ ./dft_detect -v -c -t 2 fm_audio.wav 2>/dev/null
sample: 39801
RS41: 0.9885
sample: 87824
RS41: 0.9851
sample: 135831
RS41: 0.9784

Ex.5
Some radiosonde types have similar signals, false detection is possible.

$ ./dft_detect -c -t 4 fm_meisei.wav 2>/dev/null
MEISEI: 0.9802
MRZ: -0.9720
MEISEI: 0.9829

Here a Meisei radiosonde seems to be more likely.

Ex.6
Confirmed detection (two hits):

$ ./dft_detect -d2 -t 4 fm_meisei.wav 2>/dev/null
MEISEI: 0.9829