View source for AIS: AIS receiver on a Raspberry Pi with RTL-SDR

Sumber: https://www.fontenay-ronan.fr/ais-receiver-on-a-raspberry-pi-with-rtl-sdr/

The automatic identification system (AIS) is an automatic tracking system that uses transponders on ships and is used by vessel traffic services (VTS). AIS information supplements marine radar, which continues to be the primary method of collision avoidance for water transport.

==System update==

 sudo apt-get update
 sudo apt-get upgrade

==RTL-SDR software installation==

Install required software for compilation :

 sudo apt-get install git cmake libusb-1.0-0-dev build-essential

Clone software from Github :

 git clone git://git.osmocom.org/rtl-sdr.git


Move to folder, compile, install and reboot :

 cd  rtl-sdr
 mkdir build
 cd build
 cmake ../ -DINSTALL_UDEV_RULES=ON
 make
 sudo make install
 sudo ldconfig
 cd ~
 sudo cp ./rtl-sdr/rtl-sdr.rules /etc/udev/rules.d/
 sudo reboot

Then we can test :
 rtl_test 

You might have the following issue :

    Found 1 device(s):
    0: Realtek, RTL2838UHIDIR, SN: 00000001

    Using device 0: Generic RTL2832U OEM

    Kernel driver is active, or device is claimed by second instance of librtlsdr.
    In the first case, please either detach or blacklist the kernel module
    (dvb_usb_rtl28xxu), or enable automatic detaching at compile time.

    usb_claim_interface error -6
    Failed to open rtlsdr device #0. 

Remove the problematic driver :

 sudo modprobe -r dvb_usb_rtl28xxu

Blacklist it by creating the following file :

 sudo vi /etc/modprobe.d/rtl-sdr-blacklist.conf

With the following content :

 blacklist dvb_usb_rtl28xxu

Then we can test again :

 rtl_test 

The output should looks like :

    Found 1 device(s):
    0: Realtek, RTL2838UHIDIR, SN: 00000001

    Using device 0: Generic RTL2832U OEM
    Found Rafael Micro R820T tuner
    Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6
    [R82XX] PLL not locked!
    Sampling at 2048000 S/s.

    Info: This tool will continuously read from the device, and report if
    samples get lost. If you observe no further output, everything is fine.

    Reading samples in async mode…
    Allocating 15 zero-copy buffers 

==RTL-SDR dongle calibration==

Go back to your home folder :

 cd ~


Install required software for compilation :

 sudo apt install build-essential libtool automake autoconf librtlsdr-dev libfftw3-dev


Clone software from Github :
 git clone https://github.com/steve-m/kalibrate-rtl


Move to folder, compile and install :

 cd kalibrate-rtl/
 ./bootstrap && CXXFLAGS='-W -Wall -O3'
 ./configure
 make
 sudo make install

Test it a few minutes to get a rough idea of the PPM deviation :

 rtl_test -p

Output :

    Found 1 device(s):
    0: Realtek, RTL2838UHIDIR, SN: 00000001

    Using device 0: Generic RTL2832U OEM
    Found Rafael Micro R820T tuner
    Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6
    [R82XX] PLL not locked!
    Sampling at 2048000 S/s.
    Reporting PPM error measurement every 10 seconds…
    Press ^C after a few minutes.
    Reading samples in async mode…
    lost at least 168 bytes
    real sample rate: 2047684 current PPM: -154 cumulative PPM: -154
    real sample rate: 2048101 current PPM: 50 cumulative PPM: -52
    real sample rate: 2048077 current PPM: 38 cumulative PPM: -22
    real sample rate: 2048198 current PPM: 97 cumulative PPM: 8
    real sample rate: 2048066 current PPM: 33 cumulative PPM: 13
    real sample rate: 2048093 current PPM: 46 cumulative PPM: 18
    real sample rate: 2048072 current PPM: 36 cumulative PPM: 21
    real sample rate: 2047986 current PPM: -6 cumulative PPM: 17
    real sample rate: 2048079 current PPM: 39 cumulative PPM: 20
    real sample rate: 2048108 current PPM: 53 cumulative PPM: 23
    real sample rate: 2048037 current PPM: 18 cumulative PPM: 23
    ^CSignal caught, exiting!

    User cancel, exiting…
    Samples per million lost (minimum): 0 

We’ll keep 23 as a rough PPM value at this stage.

Start to search for 900Mhz GSM stations :

 kal -s 900 -g 49.6 -e 23

Output :

    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 – 16.587kHz) power: 869529.54
    chan: 4 (935.8MHz + 38.960kHz) power: 2190452.67
    chan: 5 (936.0MHz – 16.799kHz) power: 4623109.31
    chan: 15 (938.0MHz + 38.865kHz) power: 815597.24
    chan: 16 (938.2MHz – 15.502kHz) power: 2225985.25
    chan: 20 (939.0MHz + 38.956kHz) power: 1047025.60
    chan: 78 (950.6MHz – 12.733kHz) power: 3137623.08
    chan: 123 (959.6MHz – 12.483kHz) power: 1856407.90 

Then let’s find the PPM using here the channel 5 (as it is the stronger) :

 kal -c 5 -g 49.6 -e 23


Output :

    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: Calculating clock frequency offset.
    Using GSM-900 channel 5 (936.0MHz)
    average [min, max] (range, stddev)
    – 11.901kHz [-11934, -11871] (63, 18.615683)
    overruns: 0
    not found: 0
    average absolute error: 35.715 ppm 

Our average absolute error is 35.715 ppm !

==RTL-AIS Software==

Go back to your home folder :
 cd ~

Clone software from Github :

 git clone https://github.com/dgiardini/rtl-ais


Move to folder, compile and install :

 cd rtl-ais
 make


Then we can run the software :

 ./rtl_ais -p 35 -n -h 192.168.1.15


 -p 35 : Software deviation in PPM found during the previous calibration.
 -n : Log AIS messages to console.
 -h : Send AIS data to the mentioned IP. Here, our desktop computer with OpenCPN.

Output :

    Edge tuning disabled.
    DC filter enabled.
    RTL AGC disabled.
    Internal AIS decoder enabled.
    Buffer size: 163.84 mS
    Downsample factor: 64
    Low pass: 25000 Hz
    Output: 48000 Hz
    Found 1 device(s):
    0: Realtek, RTL2838UHIDIR, SN: 00000001

    Using device 0: Generic RTL2832U OEM
    Found Rafael Micro R820T tuner
    Log NMEA sentences to console ON
    AIS data will be sent to 192.168.1.15 port 10110
    Tuner gain set to automatic.
    Tuner error set to 35 ppm.
    Tuned to 162000000 Hz.
    Sampling at 1600000 S/s.
    !AIVDM,1,1,,B,6>jCJckfJjOt>db70104@00,0*71
    !AIVDM,1,1,,B,E>jCJcl32bh87ab@87a:1RP0000?rnLv=Q?ih50b>:0,0*6A
    !AIVDM,1,1,,B,6>jCJckfJjOt>db7@104@00,0*01
    !AIVDM,1,1,,A,6>jCJckfJjOt>db70104@00,0*72
    !AIVDM,1,1,,B,E>jCJcl32bh87ab@87a:1RP0000?rnLn=Q?j@50b>:0,0*59
    !AIVDM,1,1,,B,6>jCJckfJjOt>db70104@00,0*71
    !AIVDM,1,1,,A,6>jCJckfJjOt>db5P104@00,0*10
    !AIVDM,1,1,,B,E>jCJcl32bh87ab@87a:1RP0000?rnM4=Q?ih50b>:0,0*29
    !AIVDM,1,1,,B,E>jCJcl32bh87ab@87a:1RP0000?rnLv=Q?gh50b>:0,0*64
    !AIVDM,1,1,,B,E>jCJcl32bh87ab@87a:1RP0000?rnLm=Q?k050b>:0,0*2B
    !AIVDM,1,1,,B,6>jCJckfJjOt>db70104@00,0*71
    !AIVDM,1,1,,A,33IWVk0Ohvwma3BK1nlAIQ@L01vP,0*64
    !AIVDM,1,1,,B,33IWVk0Ohrwma5vK1o2QRQFV00qh,0*27
    !AIVDM,1,1,,A,13IWVk0Ohrwma74K1o;iS1Hd0L10,0*6E
    !AIVDM,1,1,,B,33IWVk000bwmabjK1pdC8jBj01r0,0*33
    !AIVDM,1,1,,B,E>jCJcl32bh87ab@87a:1RP0000?rnLk=Q?ih50b>:0,0*77
    !AIVDM,1,1,,A,13IWVk000IwmbLnK1qS8;h6d08jCJckfJjOt>db6h104@00,0*28
    !AIVDM,1,1,,B,33IWVk0Oh5wmbIJK1qALP@l:01o@,0*31
    !AIVDM,1,1,,A,33IWVk0Oh7wmbI8K1qBdEPnB00pP,0*18
    !AIVDM,1,1,,B,13IWVk0Oh6wmbHVK1qCdQhpJ087:,0*69
    !AIVDM,1,1,,B,33IWVk0Oh7wmbHHK1qEdDPpT013@,0*36
    !AIVDM,1,1,,A,13IWVk0Oh7wmbH0K1qFt00rd05C0,0*7E
    !AIVDM,1,1,,A,33IWVk0Oh8wmbGJK1qHch0rr00ih,0*26
    !AIVDM,1,1,,B,13IWVk1009wmbG:K1qJ;g0s005C0,0*11
    !AIVDM,1,1,,A,13IWVk1008wmbFRK1qLKl@wB0<10,0*7A !AIVDM,1,1,,B,13IWVk1Oh6wmbDPK1qTu0QjCJckfJjOt>db5P104@00,0*10
    !AIVDM,1,1,,B,13IWVk1Oh4wmbCnK1qadqQE000R@,0*3A
    !AIVDM,1,1,,A,13IWVk1Oh3wmbCrK1qcM0iGB08Gw,0*2A
    !AIVDM,1,1,,B,13IWVk1Oh3wmbD6K1qeP@1KV05C4,0*0B
    !AIVDM,1,1,,A,13IWVk1003wmbChK1qh=jCJcl32bh87ab@87a:1RP0000?rnLq=Q?gh50b>:0,0*63
    !AIVDM,1,1,,A,33IWVk1003wmbCFK1qlej1Rd0AfJ,0*48
    !AIVDM,1,1,,A,13IWVk1003wmbCFK1qp@:1WB0000,0*5D
    !AIVDM,1,1,,A,13IWVk1Oh1wmbCJK1qru21f40000,0*0C
    !AIVDM,1,1,,B,33IWVk1001wmbBLK1qsnP1v80Dhr,0*27
    !AIVDM,1,1,,A,33IWVk1000wmbCDK1qeoHAp20EjCJcl32bh87ab@87a:1RP0000?rnLq=Q?j@50b>:0,0*46
    !AIVDM,1,1,,B,6>jCJckfJjOt>db70104@00,0*71
    !AIVDM,1,1,,A,E>jCJcl32bh87ab@87a:1RP0000?rnLi=Q?j@50`b>:0,0*5D
    !AIVDM,1,1,,A,6>jCJckfJjOt>db70104@00,0*72
    !AIVDM,1,1,,B,6>jCJckfJjOt>db5h104@00,0*2B 

This messages could be decoded online, for example here : http://ais.tbsalling.dk/

==OpenCPN client==

Here is my configuration:
* 192.168.1.12 : Raspberry Pi Zero with RTL-SDR dongle
* 192.168.1.15 : Laptop with Ubuntu desktop and OpenCPN software

Desktop OpenCPN configuration :
* Using the debug window, we can check that AIS messages are well received by OpenCPN :
* And AIS targets are shown on the map :

All done !






==Referensi==

* https://www.fontenay-ronan.fr/ais-receiver-on-a-raspberry-pi-with-rtl-sdr/

==Pranala Menarik==

* [[RTL-SDR]]
* [[AIS]]
* [[ADS-B]]