this is the radioteletype marker, with morse code ID, as recorded
in 1986 (rb)
listen to their call from 2182 kHz, recorded in 1988 by Rudy
van Dalen
see here a detailed letter
(Rudy van Dalen, 1982)
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Callsigns:
GNF
Frequencies Voice:
1707
1848
2182
Frequencies Morse Telegraphy:
417
418
500
512
Frequencies Radioteletype:
3607.3
Systems used:
SITOR