August 07, 2018

Swedish icebreaker Oden and the mystery of SA2LLL/63

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This is the Swedish icebreaker Oden. Built in 1988 and originally used in winter time to keep open the shipping lanes of the Gulf of Bothnia, she was later modified to be used as a polar research vessel. The Oden has been on many expeditions both to the Arctic and the Antarctic, and she was the first non-nuclear surface vessel to reach the geographic North Pole! Seven more visits to the North Pole have followed since.

Currently the Oden is on a research expedition called Arctic Ocean 2018, a joint effort of the Swedish Polar Research Secretariat and the USA's National Science Foundation. At the beginning of August, the Oden left Longyearbyen, Svalbard and started the first part of the expedition to the north polar pack ice. At some point during the expedition, for the duration of about one month, the Oden will be moored at a large Arctic Ocean ice floe and will slowly drift with it towards the North Pole.

The good news for the ham community is that onboard the Oden is amateur radio operator Lars Lehnert SA2LLL (ex DL1LLL). According to his page and his special Facebook page, Lars will be active from the Oden with the special callsign 8S8ODEN, in PSK, SSB, and WSPR!

I noticed that at the end of July and on August 1st, Lars was already making WSPR spots from the Oden as SA2LLL/MM on the 20m band from grid JQ78tf (Longyearbyen, Svalbard) (Fig. 1). I was not aware of this, and unfortunately was not doing any 20m WSPRing during that time.

Fig. 1  Lars Lehnert SA2LLL/MM making spots on 20m WSPR from the Swedish icebreaker Oden in grid JQ78tf.

When I was doing a 20m WSPR monitoring-only session though on August 3rd, I did receive some WSPR transmissions from SA2LLL/63, three in total, all consistently on 14.097042 MHz and with a DT of around 4 seconds (which is unusually large) (Fig. 2). I have no doubt this was Lars WSPRing from the Oden in the Arctic Ocean, but I have no clue what the /63 stands for. My WSJT-X did not upload the spots to, or at the database were simply ignored, most likely due to the received messages not containing a grid locator.
I checked the database, but no SA2LLL/63 spots could be found at all made by any other listeners.

Fig. 2  PA7MDJ receiving SA2LLL/63 on 20m WSPR. Receiver and antenna used were an SDRPlay RSP1A and an EFHW wire antenna. Note the frequency and the unusual large DT!

Then some time later that same day I received what probably was the matching second part of the SA2LLL/63 compound WSPR message (Fig. 3). When transmitting a compound callsign in WSPR it will be done in a two-transmission sequence; one carries the callsign and dBm power level, and the other carries the grid locator. When both are received, the WSJT-X or WSPR software will match the two transmissions in the decode screen.

The grid received was JQ78tf, which, looking at the frequency and the fact that SA2LLL/MM already used this grid at the end of July / 1st of August I have no doubt this was also originating from the Oden (Fig. 3). Unfortunately my WSJT-X did not make the match with the SA2LLL/63 message part (probably a too long time between the last reception of the part containing the callsign and the second part containing the grid locator).

Fig. 3  PA7MDJ receiving the second part of the SA2LLL/63 compound message containing the grid locator. Note the frequency and the DT!

Strange thing is that on August 3rd the Oden according to the special Arctic Ocean 2018 web page was not in grid JQ78tf (Longyearbyen, Svalbard) anymore, but already was in another grid north of the Svalbard Archipelago (Fig. 4). It might be that Lars overlooked to update the grid locator (which is quite a hassle on a moving ship when not done automatically). What also puzzles me is why other monitoring stations (many of them equipped much better than I am) also failed to receive the complete matched compound transmissions (as shown by the lack of spots in the WSPRnet database).

Fig. 4  The position of the Oden on August 3rd, north of the Svalbard Archipelago.

Then I remembered that the official WSPR manual notes that when sending compound callsigns, an add-on suffix can be either a single letter or one or two digits. A single letter! So in WSPR TX the /MM add-on will not be possible! I started wondering if maybe the /MM add-on when transmitted would decode into /63.
I decided to do an experiment, and in the settings of my WSPR 2.0 program added /MM to my callsign. I let WSPR 2.0 do some TXing and with a virtual audio cable fed the audio to WSJT-X (please note, no actual RF transmitting was done!) And lo and behold, WSJT-X decoded the messages into PA7MDJ/63 (Fig. 5)! And also, WSJT-X failed to make a match between the two compound messages! I say no more, I guess the mystery is solved.

Fig. 5  The experiment with PA7MDJ/MM sent by WSPR 2.0 and decoded as PA7MDJ/63 in WSJT-X. No match between the two compound messages is made (normally with a match the dots in the < ... > part would be replaced by the callsign).

At PA7MDJ nothing has been heard from the Oden since August 3rd, but Lars mentions on the special 8S8ODEN Facebook page, that he can use the 8S8ODEN callsign as soon as they're in international waters. I'm now regularly monitoring 20m WSPR and anxiously await the special callsign to pop up in my WSJT-X decodes.

"Normal " satellite coverage (like INMARSAT) in the High Arctic is minimal to non-existent, and I guess any Facebook or other internet media updates from Lars during the expedition will be sporadic to none.

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