Wednesday, March 29, 2017

Decoding pagers with rtl-sdr

This works.

$ rtl_fm -o 4 -A lut -s 22050 -f 148.137M - | multimon-ng -t raw -a POCSAG512 -a POCSAG1200 -a POCSAG2400 -f alpha /dev/stdin
Warning: -o is very buggy
multimon-ng  (C) 1996/1997 by Tom Sailer HB9JNX/AE4WA
             (C) 2012-2014 by Elias Oenal
available demodulators: POCSAG512 POCSAG1200 POCSAG2400 FLEX EAS UFSK1200 CLIPFSK FMSFSK AFSK1200 AFSK2400 AFSK2400_2 AFSK2400_3 HAPN4800 FSK9600 DTMF ZVEI1 ZVEI2 ZVEI3 DZVEI PZVEI EEA EIA CCIR MORSE_CW DUMPCSV SCOPE
Enabled demodulators: POCSAG512 POCSAG1200 POCSAG2400
Found 1 device(s):
  0:  Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
Tuner gain set to automatic.
Tuned to 148401600 Hz.
Oversampling input by: 12x.
Oversampling output by: 4x.
Buffer size: 7.74ms
Exact sample rate is: 1058400.010094 Hz
Sampling at 1058400 S/s.
Output at 22050 Hz.
POCSAG512: Address:  158460  Function: 0  Alpha:   57973-1 
POCSAG512: Address: 2007607  Function: 1 
POCSAG512: Address: 1741522  Function: 0 
POCSAG512: Address: 1705329  Function: 0  Alpha:   69u'2-88

multimon-ng comes from here. I found the frequency by running CubicSDR.

This post is a note to future me.


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