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1724Re: APRS-IS Rx-only iGate with rtl dongle

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  • marco.kubon
    May 19, 2013
      Hi Mathison,

      multimonNG needs an sample rate of 22050 Hz so you have to add -s 22050 to the commandline. You also need to add a "-" at the end of rtl_fm to get the data an the stdout.

      sudo rtl_fm -f 144390000 -s 22050 - | multimonNG -a AFSK1200 -t raw /dev/stdin

      It's also recommended to get the ppm with the kalibrate tool and add the ppm to rtl_fm with the -p option. I also use the -g option to set up the maximum gain based on the antenna.

      If you don't want to use the sudo command you have to install the rtl-sdr.rules into /etc/udev/rules.d/ folder. Then the normal user can use the rtl dongle.

      Best regards,
      Marco

      --- In Raspberry_Pi_4-Ham_RADIO@yahoogroups.com, "mathisono" <mathisono@...> wrote:
      >
      > sudo rtl_fm -f 144390000 | multimonNG -a AFSK1200 -t raw /dev/stdin
      >
      > This dosent yeald 144.390mhz????
      >
      > multimonNG (C) 1996/1997 by Tom Sailer HB9JNX/AE4WA
      > (C) 2012 by Elias Oenal
      > available demodulators: POCSAG512 POCSAG1200 POCSAG2400 EAS UFSK1200 CLIPFSK AFSK1200 AFSK2400 AFSK2400_2 AFSK2400_3 HAPN4800 FSK9600 DTMF ZVEI SCOPE
      > Enabled demodulators: AFSK1200
      > Found 1 device(s):
      > 0: Generic, RTL2832U, SN: 77771111153705700
      >
      > Using device 0: Generic RTL2832U (e.g. hama nano)
      > Found Elonics E4000 tuner
      > Oversampling input by: 42x.
      > Oversampling output by: 1x.
      > Buffer size: 8.13ms
      > Tuned to 144642000 Hz.
      > Sampling at 1008000 Hz.
      > Output at 24000 Hz.
      > Exact sample rate is: 1008000.009613 Hz
      > Tuner gain set to automatic.
      > --------------------------------
      >
      > something is off! the input sxntax is diffrent. as seen on the RTL site.
      > ------------------
      > For example, the following command will do reception of commercial wide-band FM signals:
      >
      > rtl_fm -f 96.3e6 -W -s 200000 -r 48000 - | aplay -r 48k -f S16_LE
      > On a Mac, a similar command that works is as follows. This assumes that the sox package is installed, 'port install sox':
      >
      > rtl_fm -f 90100000 -W -s 200000 -r 48000 - | play -r 48000 -t s16 -L -c 1 -
      > ---------------------------
      >
      > Im not sure were the problem resides? Ive never encountered this, as that ive only used the tcp_server, ive never had SET the RTL to a specific FRZ. 144.14e6 results in: 144392000 Hz.
      >
      > 73 Mathison
      >
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