Downsample

Beschreibung

Downsamples iq input, e.g. to extract Hamradio band from raw SDR input with more bandwidth. This tool is used at the SDR-Buffer
https://wiki.oevsv.at/wiki/SDR-Buffer
https://websdr.iks.tugraz.at/sdrbuffer/

Beispiel: ./downsample_x64 -a 0.1709 -F u8 -f u8 -i /dev/stdin -l 64 -o /dev/stdout -r 0.1709

Downsamples 2.048 MHz bandwidth to 350kHz
-l and -a are used against aliasing effects.
-s is necessary if not the center of the spectrum should be used.

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Übersicht der Parameter

downsample  -h

 shift frequency and up/downsample iq-file
 -a <aliasingfilter> manual set antialiasing filter 0.0..1.0 else automatic
 -F <input format>   u8 i16 f32 (u8)
 -f <output format>  u8 i16 f32 (u8)
 -g <factor>         gain (1.0)
 -h
 -i <infile>         iq file
 -l <fir length>     fir length 4..4096 with linear more cpu usage (64)
 -o <outfile>        iq file
 -r <ratio>          output to input sampelrate 0.02..5.0 (1.0)
 -s <shift>          shift frequency before resample -0.5..0.5 of iq rate (0.0)
 -v <cnt>            show output level, overdrives on stderr every <cnt> output sample (0)