Interesting,
So the traffic you're hearing on 29.875 MHz FM is similar to what I've logged on:
29.775 MHz FM
30.000 MHz FM
30.025 MHz FM
30.100 MHz FM
30.300 MHz FM
30.775 MHz FM
30.900 MHz FM
31.100 MHz FM
31.800 MHz FM
31.900 MHz FM
32.175 MHz FM
And others, all following the 25 kHz channel steps, all without a CTCSS or DCS tone/code...
It appears to be fishery radio service, using equipment designed specifically for fleet radio communications:
25 watt power
FM voice mode and FSK data mode (to transmit GPS location)
480 channels, 25 kHz spacing
27.5 MHz to 39.475 MHz
27.500 MHz FM - Channel 1
27.525 MHz FM - Channel 2
27.550 MHz FM - Channel 3
39.475 MHz FM - Channel 480
31.100 MHz FM fishery radio signals:
https://www.youtube.com/watch?v=aVSM84fMShghttps://www.youtube.com/watch?v=iBqIHvWo-Mkhttps://www.youtube.com/watch?v=FFll-usSQqohttps://www.youtube.com/watch?v=Mc59ihfl6OIhttps://www.youtube.com/watch?v=cRL2cL5sdcwhttps://www.youtube.com/watch?v=oUKQFvsOc-A30.775 MHz FM fishery radio signals:
https://youtu.be/RJZl7Ic6VgQhttps://youtu.be/7ce5kJPhSxY30.300 MHz FM fishery radio signals:
https://www.youtube.com/watch?v=EQ8xy1sTyLkhttps://www.youtube.com/watch?v=8hQAfNIj_mIhttps://www.youtube.com/watch?v=vbmKAJPjgD431.800 MHz FM fishery radio signals:
https://www.youtube.com/watch?v=RBGnBMnD9QIAnd those are just the ones I managed to get video of. 480 channels, 27.500 to 39.475, straight sequence. So 29.875 MHz FM is channel 100 on these radios. Look up FT-801 Fishing Boat Radio or FT-801 Dedicated Fisheries Radio.
The bands have been alive lately and a lot of VHF low band 29.7 to 50 MHz signals have been coming in (along with 11m signals), but what sets these Asian fishery radio signals apart is the fact that they have no CTCSS (PL tone) or DCS (DPL code) selective calling signals transmitted with them.
They use regular old carrier squelch (CSQ). 99% of the land mobile (and military) comms I've heard in the 30-50 MHz band (and the 29.7 MHz to 30 MHz band) have a CTCSS tone or a DCS code transmitted, to prevent QRM from skip propagation...exactly this situation.
Yes, the 25 kHz steps do match with the standard 30.000 MHz to 87.975 MHz military FM tactical radio plan, but the military use a 150.0 Hz tone squelch system as well. It's not one of the standard land mobile tones, but my receivers do decode it as 151.4 Hz (the closest land mobile tone to 150 Hz). None of these fishery transmissions with the Asian language have had any tones at all, regardless of signal strength. There are plenty of other land mobile radio systems on these frequencies (a good example is 31.200 MHz, which fits within the 25 kHz channel steps 27.500 MHz to 39.475 MHz band plan) but the traffic on there is in Spanish and has a CTCSS tone (usually I hear signals with a 203.5 Hz tone, but other tones have been logged as well, it's Latin American and Caribbean taxi cab dispatchers).
By process of elimination, I think what you heard on 29.875 MHz FM is one of these VHF Low FM "Dedicated Fisheries Radio" 27.5-39.475 MHz 480 Channel FM Fishing Boat Radio systems....or you were hearing a different land mobile system that happened to also be on 29.875 MHz. There's actually a lot of stuff within that little piece of bandwidth between 29700 and 30000. In the USA the frequencies 29.710 MHz, 29.730 MHz, 29.750 MHz, 29.770 MHz and 29.790 MHz are active land mobile (business radio) frequencies.
They are still used and are still active. Of course there are freeband CB operators there, but not as many as there are below 28 MHz.
Here is the full channel to frequency list:
https://www.hfunderground.com/wiki/CB#China.2FHong_Kong_Chinese_27.5-39.5_MHz_HF_and_VHF-low_Fishery_Marine_Band_FM_Fishing_Radio
Topic: French on 29875 FM - 1420 / 1425 UTC - 7 November 2022 (Read 984 times)
