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Installieren eines AIS-Datenempängers

Benötigte Software

  • librtlsdr0 (aus den Debian-Repositories)
  • node-underscore (aus den Debian-Repositories)
  • node-colors (aus den Debian-Repositories)
  • node-sprintf-js (aus den Debian-Repositories)
  • librtlsdr-dev (aus den Debian-Repositories)
  • libfftw3-dev (aus den Debian-Repositories)

Software installieren

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sudo apt-get update && sudo apt-get install -y librtlsdr-dev libfftw3-dev \
  node-underscore node-colors node-sprintf-js
mkdir -p repos
cd repos
git clone https://github.com/dgiardini/rtl-ais
cd rtl-ais
make
sudo make install
cd ..
git clone https://github.com/steve-m/kalibrate-rtl.git
cd kalibrate-rtl
./bootstrap && CXXFLAGS='-W -Wall -O3'
./configure
make
sudo make install

Empfänger kalibrieren

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kal -s GSM900 -g 49.6

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Found 1 device(s):
  0:  Generic RTL2832U OEM

Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
Exact sample rate is: 270833.002142 Hz
[R82XX] PLL not locked!
Setting gain: 49.6 dB
kal: Scanning for GSM-900 base stations.
GSM-900:
    chan:    2 (935.4MHz - 34.678kHz)    power: 1008362.81
    chan:    6 (936.2MHz - 34.519kHz)    power: 2247153.24
    chan:    9 (936.8MHz + 30.616kHz)    power:  491338.30
    chan:   19 (938.8MHz + 30.173kHz)    power:  325716.01
    chan:   21 (939.2MHz + 29.361kHz)    power:  618493.93
    chan:   45 (944.0MHz + 39.270kHz)    power: 1890859.05
    chan:   46 (944.2MHz - 34.664kHz)    power: 3820670.88
    chan:   53 (945.6MHz - 34.802kHz)    power:  236747.55
    chan:   57 (946.4MHz - 35.512kHz)    power:  407476.66
    chan:   63 (947.6MHz - 34.401kHz)    power:  346496.45
    chan:   71 (949.2MHz + 19.256kHz)    power:  183371.78
    chan:   72 (949.4MHz - 34.497kHz)    power:  246555.51
...chan 120
Difference of offsets between channels is >1kHz. This likely means that the correct PPM is too far away and you need to provide a rough estimate using the '-e' option. Try tuning against a local FM radio or other known frequency first.

Wir wählen den Kanal mit der höchsten Leistung aus. In diesem Fall ist das Kanal 46 mit 3820670.88.

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kal -c 46
Found 1 device(s): 0: Generic RTL2832U OEM

Using device 0: Generic RTL2832U OEM Found Rafael Micro R820T tuner Exact sample rate is: 270833.002142 Hz [R82XX] PLL not locked! kal: Calculating clock frequency offset. Using GSM-900 channel 46 (944.2MHz) Tuned to 944.200000MHz (reported tuner error: 0Hz) average [min, max] (range, stddev) - 34.779kHz [-34790, -34770] (20, 4.941575) overruns: 0 not found: 0 average absolute error: 36.835 ppm 

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Die letzte Zeile enthält die Abweichung in ppm. In diesem Fall 36.835 ppm. Wir runden und merken uns die Abweichung von 37 ppm.

## Empfänger starten

Den Empfänger starten wir nun mit

```bash
rtl_ais -n -p 37 -R -g 49.6 -P8080