29.875 MHz FM 29875 kHz FM Asian Fishing Fleet Fishery Radio Chatter 9 June 2023

[R4002]

Heard via the G8JNJ RaspSDR UK based online receiver.  Band opening up, 11m and 10m along with VHF low band starting to open. 

The usual chatter on 29.875 MHz - Asian fishermen comms fishing fleet radio network 29875 FM 29.8750 FM [CSQ] 29,875kHz FM 29.875MHz FM CSQ simplex FM no tone.  Good quality audio at around 1130 UTC. 

These guys are running the de facto standard "FM Fishery Radiotelephone" system - 480 channel, channelized high-HF/low-VHF 25 watt radios. 

27.500 MHz to 39.475 MHz.  Some list the coverage as 27.5 MHz - 39.5 MHz or 27.500 MHz to 39.500 MHz.  The standard version uses 25 kHz channel steps, with straight numbering sequence. 

27.500 MHz FM - Channel 1
27.525 MHz FM - Channel 2
27.550 MHz FM - Channel 3
27.575 MHz FM - Channel 4 and so on


29.875 MHz FM is Channel 100 on that channel plan.  I've noted activity on 27.750 MHz FM, 27.775 MHz FM, 27.900 MHz FM, 27.975 MHz FM, 28.000 MHz FM, 29.150 MHz FM, 29.700 MHz FM, 29.725 MHz FM, 29.750 MHz FM, 29.775 MHz FM, 29.825 MHz FM and many many others (including even more above 30 MHz). 

The radios do cover the entire 28 MHz - 29.7 MHz 10m amateur band, and they've been monitored in-band, but usually they seem to stay between 27.500 MHz and 28.000 MHz and 29.700 MHz and 39.475 MHz.

There are apparently some "export" versions of these rigs that reduce the channel spacing from 25 kHz to 12.5 kHz (and reduce the FM deviation from 4 kHz/5 kHz to 2.5 kHz), producing double the available channels.  The indications are that most users are running the 25 kHz channel band plan.  However, frequencies 29.8875 MHz FM, 29.9625 MHz FM, 30.3625 MHz FM, 32.1125 MHz FM, 32.1625 MHz FM, 32.1875 MHz FM and several others have had Asian fishing fleet traffic monitored on them.

With the band open almost every day now...I expect more of these systems will start appearing.   Japan still has their two DSB fishing fleet radio telephone systems (in other words, AM mode).  Double sideband fishery radiotelephone service.  There's the

1W DSB 27MHz service AM voice and data
(26760 kHz to 27988 kHz or 26.760 MHz to 27.988 MHz, odd steps)

5W DSB 40MHz service AM voice and data
39.008 MHz to 39.928 MHz transmit/receive, 8 kHz channel spacing
35.544 MHz to 35.928 MHz ship receive only 8 kHz channel spacing (shore transmit)

The reason for the 35 MHz - 36 MHz shore transmit frequencies is, I believe, for half-duplex or even full duplex ship-to-shore comms.  Various Japanese fishing companies fisheries have licenses for the 35-36 MHz frequencies and the 39-40 MHz frequencies - indicating that the 39MHz band is used for ship-to-ship and ship-to-shore comms. 

Japan also has a 25W SSB 27MHz fishery radio service 27.3105 MHz to 27.4705 MHz or 27310.5 kHz to 27470.5 kHz, odd spacing, USB mode.

South Korea has a fisheries radio service at 27 MHz as well: 27.508 MHz to 27.943 MHz.  Like the Japanese 1 watt DSB AM 27 MHz fishery radio service, the channel spacing is very random. 

Add to that the fact that numerous other Asia - Pacific countries with large fishing fleets have what they simply call "marine CB" or "boat CB radio".  Usually that means one of the following:

26.065 MHz to 28.755 MHz - AM, FM, USB and LSB modes
25.550 MHz to 30.500 MHz - AM, FM, USB and LSB modes
26.475 MHz to 27.275 MHz - AM mode (other variants include 25.550 MHz to 27.270 MHz, also AM mode)
25.615 MHz to 30.105 MHz - AM, FM, USB and LSB modes

The 26.065 MHz to 28.755 MHz and 25.615 MHz to 30.105 MHz versions are the most popular.  All of them appear to use 10 kHz spacing, just like regular old export CB radio.