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GMDSS signal monitoring (DSC) with RaspberryPi2

Finally you can decode station identification data such as MMSI code and ship coordinates on RaspberryPi 2. For now I'm decoding the signals using the external sound card and a Tecsun PL-660 receiver with external antenna (A wire dipole for 40 meters and, on other frequencies, a rotary dipole for 10/15/20 meters). The project is still under development, I used a Python script that I found here, the next adventure will be to make the script work with RTLSDR V.3. 😋 Works in progress..

Reception to 8414.5 mHz 






 

=== DEBUG DATA message ===
Message found at 15
(125)(111)(125)(110)(125)(-45)(125)(108)(-121)(107)(125)(106)(-120)(-105)(-120)(104)(0)(120)(-23)(120)(71)(0)(0)(23)(0)(-67)(-104)(0)(27)(0)(-2)(-96)
------------------------------------------------

=== DEBUG DATA message ===
Message found at 57
(125)(111)(125)(110)(125)(109)(125)(108)(125)(107)(125)(106)(120)(105)(120)(104)(0)(120)(23)(-88)(91)(0)(0)(23)(0)(91)(108)(0)(24)(0)(92)(108)(87)(24)(0)(92)(0)(87)(118)(0)(126)(0)(126)(118)(126)(126)(126)(126)(126)(126)(126)(126)(126)(126)(117)(126)(54)(126)(117)(117)(117)(54)(-63)(-63)(-125)(-127)
------------------------------------------------
------------------------------------------------
<2023Mar11-13:08:17> Format specifier 120: Selective individual call
Address:
MID (Country): 239 Coast station  MMSI: 1000 Greece
<Safety>
Self ID:
MID (Country): 249 Individual  MMSI: 287000 Malta
<Test>
<No information>
Called station receive frequency:
<126126126> No frequency information
Called station transmit frequency:
<126126126> No frequency information
<EOS for Acknowledgement required>

=== DEBUG DATA message ===
Message found at 60
(125)(-110)(125)(110)(125)(109)(-124)(108)(125)(107)(125)(106)(120)(105)(120)(104)(63)(120)(60)(120)(21)(63)(34)(60)(60)(-53)(108)(34)(0)(-124)(23)(108)(71)(0)(0)(23)(0)(71)(118)(0)(126)(0)(-4)(-118)(12)(126)(-54)
------------------------------------------------
------------------------------------------------
<2023Mar11-13:12:44> Format specifier 120: Selective individual call
Address:
MID (Country): 241 Individual  MMSI: 199000 Greece
<Safety>
Self ID:
MID (Country): 237 Coast station  MMSI: 1000 Greece
<Test>
<No information>
Called station receive frequency:
<041250> HF frequency: 041250
Called station transmit frequency:
<041250> HF frequency: 041250
<EOS for Acknowledgement given>
------------------------------------------------
<2023Mar11-13:21:39> Format specifier 120: Selective individual call
Address:
MID (Country): 212 Individual  MMSI: 452000 Cyprus (Republic of)
<Safety>
Self ID:
MID (Country): 237 Coast station  MMSI: 1000 Greece
<Test>
<No information>
Called station receive frequency:
<041250> HF frequency: 041250
Called station transmit frequency:
<041250> HF frequency: 041250
<EOS for Acknowledgement given>

=== DEBUG DATA message ===
Message found at 31
(125)(-109)(-125)(110)(125)(109)(-109)(108)(125)(-111)(29)(-110)(-56)(-73)(-125)(104)(-4)(-120)(-23)(120)(71)(0)(0)(23)(-1)(71)(108)(0)(-24)
------------------------------------------------

=== DEBUG DATA message ===
Message found at 44
(125)(111)(125)(110)(125)(-111)(125)(108)(125)(107)(125)(106)(120)(-105)(-88)(104)(-127)(61)(60)(-56)(17)(63)(55)(60)(50)(17)(108)(55)(0)(-50)(-23)(-124)
------------------------------------------------
------------------------------------------------
<2023Mar11-14:50:56> Format specifier 120: Selective individual call
Address:
MID (Country): 636 Individual  MMSI: 019296 Liberia (Republic of)
<Safety>
Self ID:
MID (Country): 237 Coast station  MMSI: 1000 Greece
<Test>
<No information>
Called station receive frequency:
<041250> HF frequency: 041250
Called station transmit frequency:
<041250> HF frequency: 041250
<EOS for Acknowledgement given>
------------------------------------------------
<2023Mar11-15:25:29> Format specifier 120: Selective individual call
Address:
MID (Country): 636 Individual  MMSI: 019547 Liberia (Republic of)
<Routine>
Self ID:
MID (Country): 237 Coast station  MMSI: 1000 Greece
<J3E TP>
<No information>
Called station receive frequency:
<041010> HF frequency: 041010
Called station transmit frequency:
<043930> HF frequency: 043930
<EOS for Acknowledgement given>

=== DEBUG DATA message ===
Message found at 32
(125)(111)(125)(110)(125)(109)(125)(108)(125)(107)(125)(106)(120)(-109)(120)(104)(21)(120)(50)(120)(15)(21)(0)(50)(0)(15)(108)(0)(-16)(0)(-87)(108)(71)(0)(0)(23)(0)(71)(118)(0)(126)(0)(4)(118)(10)(126)(10)(-5)(4)(10)(39)(10)(30)(4)(122)(39)(39)(30)(122)(122)(122)(39)(0)(-119)(-52)
------------------------------------------------
------------------------------------------------
<2023Mar11-16:01:54> Format specifier 120: Selective individual call
Address:
MID (Country): 215 Individual  MMSI: 015000 Malta
<Safety>
Self ID:
MID (Country): 237 Coast station  MMSI: 1000 Greece
<Test>
<No information>
Called station receive frequency:
<041010> HF frequency: 041010
Called station transmit frequency:
<043930> HF frequency: 043930
<EOS for Acknowledgement given>

=== DEBUG DATA message ===
Message found at 76
(125)(111)(125)(110)(125)(109)(125)(108)(125)(107)(125)(106)(120)(105)(120)(-106)(21)(120)(50)(120)(15)(21)(-64)(50)(0)(-13)(108)(0)(0)(0)(23)(108)(71)(0)(0)(23)(0)(71)(118)(0)(126)(0)(4)(118)(10)(126)(-10)(4)(4)(10)(-7)(10)(30)(4)(122)(39)(-38)
------------------------------------------------
------------------------------------------------
<2023Mar11-16:04:57> Format specifier 120: Selective individual call
Address:
MID (Country): 215 Individual  MMSI: 015000 Malta
<Safety>
Self ID:
MID (Country): 237 Coast station  MMSI: 1000 Greece
<Test>
<No information>
Called station receive frequency:
<041010> HF frequency: 041010
Called station transmit frequency:
<043930> HF frequency: 043930
<EOS for Acknowledgement given>


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Comments

Ramon said…
Very interesting, especially if one could then feed this information to an app like AIS-Catcher.
You may have an issue using a RTLSDR-v3 because most of these SDRs don't work in the HF bands. You'd have to use a RSP1A or Airspy HF+ or something similar to get HF coverage.

Last question -- is there a list of HF frequencies that are used for GMDSS or other marine data? I'd be interested to see if there's a way to enhance my current VHF AIS reception with vessel data from a bit further away than VHF range.

Tnx - 73 - Ramon KX1T (Boston, MA, USA)
12 March 2023 at 13:34
IT9YBG said…
Hi Ramon, I don't think you can provide information with this python script to AIS-Catcher. With the RTLSDR V.3 dongle, after so many days of testing, I managed to get it working with the script, so now I only use the RTL dongle and the raspberryPi2. :-) Soon I will publish everything on this page.
To improve AIS VHF reception you need a good nautical antenna tuned to those frequencies and a good cable.
The frequencies used in Hf for GMDSS are: 2182-2187.5-4207.5-6312-8414.5-12577 and 16804.5 kHz.
12 March 2023 at 18:42
Signal Iduna said…
is there a list of HF frequencies that are used for GMDSS
6 April 2023 at 09:38
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