Any word on VHF Marine radio digital voice
- Thread starter NY1PD
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mmckenna
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I haven't heard of anyone testing it. Last time I looked, this was still a long term plan from the ITU and no country had adopted it yet. The interim plan is still narrow band FM.
The current ITU plan is for a 6.25KHz digital FDMA format, similar to NXDN, although they don't name the protocol. In testing, 6.25KHz digital does provide better coverage than 25KHz or 12.5KHz analog.
But, since it's simplex, dead spots are totally an individual thing dependent on where the transmitters and receivers are. Coverage on dry land isn't anyones priority for Marine VHF.
Monitorman7001
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It’s going to be a modified version of dPMR not NXDN
mmckenna
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dPMR and NXDN are very similar.
Like I said, ITU hasn't released any info on the specification itself, other than 6.25KHz digital FDMA, the ability to send GPS location with PTT, data and a few other hints.
I doubt most of us will be around when this finally hits the market.
paulears
Member
Marine users in the UK are very unlikely to buy any radio that is more complicated, or offers no advantages unless the old radio dies. The killer is safety. The entire marine system is designed to stop people getting hurt. Users are unskilled, and often untested despite the rules. Some even have licences! Some people hate the robotic style voice and it’s probable that digital wont work well with high levels of wind and engine noise. The quality of many marine voice messages is terrible, you can hardly hear them against the noise. You also need to consider the negative aspects of using digital. The fact it remains loud and clear up to the point where the noise level increases with distance. The horizon means marine traffic is often right at the maximum range where digital performance is bad. The marine repeat method where a ship calls its callsign three times and the same with important stuff, the “I say again” is because it works the best. Digital just gives up. You could have controlled docks or ports where access is restricted to digital radio users only. We actually have that here. Our large wind farms use channel 14 in port, but as soon as they leave they use a digital radio to enter the wind farm control zone. But this is not a safety system for general mariners, it’s a system for authorised vessels who get permissions, access and control information.
look at the aviation migration. Digital was not mandated. Their reasons for remaining with AM were solid. Aviation has tight control, radio fitting and maintenance by registered people and controlling authorities in every country. Marine really has little control by anyone other than the coastguards, and they give guidance usually with no actual authority.
at the moment, digital offers more facilities but is not better. When it is, it will be rolled out. The move from 50khz to 25khz channel spacing too a few years to bed in and we still have a few vessels here with old radios, with the higher deviation that sound like everyone is shouting, but they still work.
look at the aviation migration. Digital was not mandated. Their reasons for remaining with AM were solid. Aviation has tight control, radio fitting and maintenance by registered people and controlling authorities in every country. Marine really has little control by anyone other than the coastguards, and they give guidance usually with no actual authority.
at the moment, digital offers more facilities but is not better. When it is, it will be rolled out. The move from 50khz to 25khz channel spacing too a few years to bed in and we still have a few vessels here with old radios, with the higher deviation that sound like everyone is shouting, but they still work.
mmckenna
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Years ago that would be true.
If you are comparing analog to the low tier Chinese radios, or improperly set up amateur radios, that would also be true.
But, if you compare analog to a properly set up digital radio that is running modern noise suppression, that would not be true.
Using a digital radio in the fire environment has resulted in manufacturers building some pretty impressive digital signal processing into the radios that will deal with a screaming Diesel engine, sirens and other noises.
mmckenna
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ITU is the one who's proposing digital VHF marine.
paulears
Member
I see your point, but they will struggle - marine users are privately funded, operate on small budgets and most importantly, are not regulated very well. The aviation community of professionals and amateurs took the step to invest in the new equipment. You can buy a perfectly reliable, useful marine radio for £70 upwards - and this is the stumbling block. Cost. Worldwide shipping comms will shift at some point, but resistance won't make it a quick. I'm also dubious about low bitrate analogue to digital conversion. The current Motorola radios in use buy the emergency services still suffer from poor signal to noise caused by operator distance and background noise. No doubt they will get better - but the day is not here yet. Looking at the radios I sell to marine users - there are a number who select sophisticated expensive ones, but the most popular are simpler and much cheaper, and for many users, still too expensive. You also have three categories of users. The very common one are the folk who buy a radio, usually a portable and hope not to use it - available for emergencies. They don't get a licence, even though OFCOM in the UK do not charge for marine licences. If they use the radio for an emergency, nobody worries about the licence. The second tier get the licence and use the radio in their small fishing or leisure boat. They don't use it much, but can get permission to enter port and use locks etc. They do NOT take the exam - which is typically £70-100 in course fees. They don't get the Mayday training, they don't get the operating practices and they don't get the communication skills primer. The responsible folk who take the test, have a licence would probably also buy a new radio if they were advised to. Until the people in category one and two still have people the other end to talk to, they won't reinvest.
There are some enthusiast users who have DMR radios for the ham bands, who have marine programmed in, and I've noticed a couple have been experimenting with digital on the unused old ship to shore telephone channels and in the gap between 37 and 50. They are sharing details of catches, trends and fisherman private stuff. However - the range between them and me is less good than when they use FM.
There are some enthusiast users who have DMR radios for the ham bands, who have marine programmed in, and I've noticed a couple have been experimenting with digital on the unused old ship to shore telephone channels and in the gap between 37 and 50. They are sharing details of catches, trends and fisherman private stuff. However - the range between them and me is less good than when they use FM.
Well, I won't be around to see it, there is already a lot of satellite marine stuff.
paulears
Member
Me neither!
mmckenna
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Yeah, me neither.
Their interim step (ITU's term for it) is analog narrowband.
ITU specs are here:
USCG page is here:
Obviously not adopted. I'd have to search and see if there are any VHF marine radios that currently support these new narrowband channels.
One option is that there are a number of Part 90 radios that also have Part 80 certs. When programmed properly by a tech holding a GROL, it would be easy enough to run narrowband on VHF marine under the current rules. The last bunch of VHF radios I've purchased at work all have Part 80 (Kenwood, Harris, Motorola), so it's doable.
But doesn't appear to be for the "consumer" level VHF marine users.