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Author Topic: Asian Fishermen Fisheries Chatter 31.000 MHz FM [CSQ] 1615 UTC 03/22/24  (Read 309 times)

Offline R4002

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Hearing the usual chatty fishermen on 31.000 MHz FM [CSQ] at 1215 local time / 1615 UTC.  31.0 MHz NFM 31000 FM carrier squelch (no squelch tone used). 

Interesting time for these guys to be coming in, usually they're stronger in the morning or evening, vs. middle of the day.  Chances are the other frequencies may start becoming active shortly too.

Fishing trawlers high HF band / VHF lowband FM radiotelephone system, originally out of China:


Original specification:
27.500 MHz to 39.475 MHz - 27.5MHz - 39.5MHz
25 kHz spacing, FM voice 16K0F3E emission
Channelized
480 channels, straight sequence

27.500 MHz FM - Channel 001
27.525 MHz FM - Channel 002
27.550 MHz FM - Channel 003
27.575 MHz FM - Channel 004
and so on (up through 10 meters) up to

39.425 MHz FM - Channel 478
39.450 MHz FM - Channel 479
39.475 MHz FM - Channel 480

Power output 25w.  Dual mode signalling, 300 baud and 1200 audio-frequency shift keying for individual calling, ship to ship call, emergency call, ship to shore station call, group call, fleet broadcast signal and other purposes.  System is entirely carrier squelch operated.

There are modified variants sold out of Taiwan and other places that use 12.5 kHz spacing to increase the number of channels to 960, and use the same selective calling systems.  Lots and lots of these radios around, likely in use worldwide.  31.000 MHz is one of the more popular frequencies, I've heard them down below 28.000 MHz, inside 10 meters, and on 29.750 MHz FM, 29.775 MHz FM, 29.800 MHz FM, 29.825 MHz FM, 29.850 MHz FM, 29.875 MHz FM and many others, including 30.000 MHz FM.  29.825MHz and 29.875MHz are very popular ones.  The 12.5 kHz "extra channels" aren't as busy but they are certainly in use.  I've logged 29.9375 MHz, 29.9625 MHz, 29.9875 MHz, 30.0125 MHz, 30.1875 MHz, 32.1125 MHz, 32.1375 MHz, and many many others.  Seems like the FM deviation is lowered when operating on the 12.5 kHz channels...except on some radios its not. 
« Last Edit: March 22, 2024, 1626 UTC by R4002 »
U.S. East Coast, various HF/VHF/UHF radios/transceivers/scanners/receivers - land mobile system operator - focus on VHF/UHF and 11m