UNID in W Scotland

david
 

Hello knowledgeable folks,

Subject line changed for clarity.
My apologies for the delay. We have had visitors, and the 'lady of the house' imposed other priorities ;(

I think this is the record for the UNID that caused John so much frowning. I hope it gives up its secrets to those who can decode it:

TIME: 2018-08-29 04:28:05 FREQ: 2187.5 DIST: -- Km
SYMB: 120 120 056 030 004 020 000 108 000 026 030 078 000 118 126 068 ~~~ ~~~ 126 ~~~ 126 122 094 122 122
FMT: SEL
CAT: SAF
TO: SHIP,563004200,???
FROM: COAST,002630780, UNID
TC1: TEST
TC2: NOINF
FREQ: --
POS: --
EOS: ACK
cECC: 94 OK

RAW FEC: 125 108 125 107 125 106 120 105 120 105 120 104 056 120 030 120 004 056 020 030 000 004 108 020 000 000 026 108 ~~~ ~~~ 078 019 ~~~ 030 118 010 126 000 ~~~ ~~~ ~~~ ~~~ ~~~ 068 126 ~~~ ~~~ ~~~ ~~~ 126 122 ~~~ 094 126 122 122 122 094 ~~~ ~~~ ~~~ 043


Best Wishes
David, GM8XBZ

-----Original Message-----
From: dsc-list@groups.io <dsc-list@groups.io> On Behalf Of John Pumford-Green
Sent: 04 September 2018 07:54
To: dsc-list@groups.io
Subject: Re: [dsc-list] REU _ DSC Logs from W Scotland


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

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