Re: REU _ DSC Logs from W Scotland

John Pumford-Green
 

Gents,

I also received the same message, from 002630100, at the same time, as did G4EMM (according to YaDDNet).

I'm using DSCDecoder at the moment...:
563004200;(safety);from;002630100; test ACK;18-08-29 04:28:09;2187.5kHz

120 120 56 30 04 20 00 108 00 26 30 10 00 118 126 126 126 126 126 126 126 122 [18-08-29 04:28:09]


David's UNID 002630780 confused me when I noticed it a couple of days ago, and still confuses me now!

It looks as though the ECC (Checksum) in David's message calculated correctly even though there's obviously an error in one of the MMSI digits (78 instead of 10).

This just goes to show that the error detection mechanism of DSC isn't foolproof. It would be interesting if David could find his copy of the message in YaDD and copy/paste the symbols so we can compare it to what Peter and I received. I'd like to see if I can explain why the Checksum in David's copy was OK despite the error.

Cheers,

John
GM4SLV

On 03/09/18 21:36, peter via Groups.Io wrote:
On 03/09/2018 09:02, david via Groups.Io wrote:
20180829 0428 2187.5 002630780 UNID, Portugal
Hi David,
Re. your Portugal UNID - This is what was logged here at same time. Hope it may help.
73,   Peter
(MF=2.1875 MHz) <Selective call to a particular individual station>
Called MMSI station address: 563004200 [Ship] (Singapore)
Category: Safety
MMSI self-identifier: 002630100 [Coast station: 38°41'N 009°19'W Lisboa MRCC Lisboa] (Portugal)
Telecommand 1: Test
Telecommand 2: No information
Neither RX/TX frequencies nor position supplied
Check Sum: OK
Date and time of decoding: 29/08/2018 04:28:09
Codes: 120 120 56 30 4 20 0 108 0 26 30 10 0 118 126 126 126 126 126 126 126 122 94

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