I’ve been trying to send out some test calls on the MF/HF and not been having much success with receiving responses, the equipment is working correctly.
When I did the GMDSS course they mentioned the distances that each frequency travels at day and at night, but I can’t really remember what they were.
I’ve been searching on Google for radio propagation tables and the like but had no success.
So can anyone tell me what the day/night distances for all the major MF/HF DSC frequencies are? Also what shore stations do people find are the best for automatically acknowledging the test messages?
Do you have a Admiralty list of radio signals on board? Or the ITU list of Coast Stations? These are pubs you should have on board, I’m not sure if the ALRS vol5 is required but I’m pretty sure the ITU coast stations and Ship stations are mandatory on GMDSS equipped vessels.
And here is a propogation table I found after a quick google search.
Band R/T Frequency DSC Frequency Day Time Range Night Time Range
MF 2182 kHz 2187.5 kHz 150 nm 500 nm
HF4 4125 kHz 4207.5 kHZ 300 nm 1000 nm
HF6 6215 kHz 6312 kHz 600 nm 1500 nm
HF8 8291 kHz 8414.5 kHZ 1000 nm 2000 nm
HF12 12290 kHz 12577 kHz 2500 nm
HF16 16420 kHz 16804.5 kHz
VHF 156.800 MHz (Ch16) 156.525 MHz (Ch 70) 30 nm 30 nm
Thanks for that info GLMASailor, that is exactly what I was looking for, have the link for the website you got that from by any chance?
Yes we have all the books your talking about there, it’s just that a lot of coast stations don’t actually seem to auto-reply when sent a DSC test message for some reason.
Radio in simplex or duplex mode? A3E or J3E (i.e. USB) or another? Use J3E.
As for frequency, the 8MHz range should work most often. Check pub117’s frequency selection guide.