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Old 14-11-2018, 13:09   #1
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Why do VHF radios only come with a AIS receiver not a transceiver?

To me it would seem simple to combine the modern VHF radios with an AIS transponder as well and cut out one bit of equipment?
Anyone think of a reason?
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Old 14-11-2018, 13:18   #2
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

You can't transmit and receive at the same time, using the same antenna and transceiver.
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Old 14-11-2018, 13:20   #3
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

Quote:
Originally Posted by Markhunter1097 View Post
To me it would seem simple to combine the modern VHF radios with an AIS transponder as well and cut out one bit of equipment?
Anyone think of a reason?
Last I heard it was the FCC type certification that was holding it up. Standard Horizon had announced a combined unit several years ago and it still isn't available. My understanding is that they just can't get it certified.

If you want both there are two ways to get all the cool AIS, DSC, VHF features working together...

1.) VHF with built-in AIS receiver (Like an Icom M506 or M605) + AIS Transponder black box (like a Vesper XB6000 or XB8000(WiFi)

2.) VHF without AIS (Like an Icom M330 or M424) + AIS Transponder with a screen (like the Icom MA500 or the Vesper Vision2)

With either of these combinations you can find and select an AIS target, and send a DSC call to it via the VHF radio without having to enter any MMSI information. And in both cases the AIS units will provide MOB alarms, AIS collision alarms, and in the Vesper case also do Anchor watch alarms.

Another AIS option is the Digital Yacht AIT3000 which has a built-in antenna splitter, so you just connect the VHF to the new AIS unit. The AIT3000 has WiFi, NMEA mux, and all sorts of stuff similar to the Vesper XB8000 but the built-in splitter is unique.

In any case, as of today, there are no VHF radios with built-in AIS transponders, and my educated guess is that FCC, SOLAS, GMDSS, and USCG regulations of various kinds are holding that back.
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Old 14-11-2018, 13:23   #4
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

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Originally Posted by denverd0n View Post
You can't transmit and receive at the same time, using the same antenna and transceiver.
Well, you can with an antenna splitter, which many boats already do.

But the question would be, do you embed an AIS transponder, antenna splitter, and VHF radio all inside one box. Is there physical room to do so and still mount in the console of most boats, or would you need a separate black box, which would negate the advantage anyway.

Also, would the price model make it harder to sell since in many cases people upgrade their VHF and AIS at different times, and could you get it to meet all of the certification requirements for AIS and VHF and DSC.
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Old 14-11-2018, 18:27   #5
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

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Originally Posted by svmobert View Post
Well, you can with an antenna splitter, which many boats already do.

But the question would be, do you embed an AIS transponder, antenna splitter, and VHF radio all inside one box. Is there physical room to do so and still mount in the console of most boats, or would you need a separate black box, which would negate the advantage anyway.

Also, would the price model make it harder to sell since in many cases people upgrade their VHF and AIS at different times, and could you get it to meet all of the certification requirements for AIS and VHF and DSC.
Thanks Richard, I don't think size is an issue, I currently run a Comar AIS receiver and splitter into a PC and when looking at upgrading to a transponder, the new unit was only slightly bigger.
I like your explanation that certification is the issue as that does really answer my question.thx
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Old 14-11-2018, 19:16   #6
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

A VHF radio would not need to transmit multiple messages at the same time. It could easily prioritize voice over the AIS message broadcast. The class B standard offers some flexibility in this regard. However, the FCC will hold the AIS unit testing to strict language in the regulations. It may be impossible to comply with the letter of those regulations if a user can press the mic button and block AIS messaging for too long. There may be other bureaucratic issues like that.

It seems obvious there would be a huge market for such a radio. Many AIS holdouts would no longer have a good reason to put off upgrading. Personally I think it will happen.

Thread drift:

I recall many years ago an FCC inspector testing a broadcast audio level meter. The meter was a new digital bar graph display. The inspector rejected the meter because it had exactly zero overshoot. The FCC standard required a certain minimum overshoot with a not to exceed level too. The design engineer groused when he had to make his new digital meter overshoot thus decreasing the accuracy. The FCC was not very flexible then and probably not now either.
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Old 14-11-2018, 23:17   #7
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

I suspect the bureaucratic inertia answer is the correct one. Perhaps some of the more radio knowledgeable members could enlighten us in respect of the full duplex subject at VHF frequencies and the implications for VHF transceivers with AIS.
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Old 14-11-2018, 23:58   #8
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

I just talked to SH yesterday at METS and asked them what the delay was on the 6500. He said they had legal patent by issues that delayed it, and it should be available in Europe shortly. No ETA on the US
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Old 15-11-2018, 09:14   #9
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

The SH 6500 is an all-in-one-box device, but it is NOT an all-in-one-transceiver device! Inside the case it contains separate transceivers for VHF and AIS. It also requires separate antennas for VHF and AIS.



Creating a device that combines VHF and AIS into one case is one thing. Creating a single transceiver that will do both simultaneously is a whole different matter (and WAAAAAY more difficult!).
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Old 15-11-2018, 10:13   #10
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

Quote:
Originally Posted by svmobert View Post
Last I heard it was the FCC type certification that was holding it up. Standard Horizon had announced a combined unit several years ago and it still isn't available. My understanding is that they just can't get it certified.

If you want both there are two ways to get all the cool AIS, DSC, VHF features working together...

1.) VHF with built-in AIS receiver (Like an Icom M506 or M605) + AIS Transponder black box (like a Vesper XB6000 or XB8000(WiFi)

2.) VHF without AIS (Like an Icom M330 or M424) + AIS Transponder with a screen (like the Icom MA500 or the Vesper Vision2)

With either of these combinations you can find and select an AIS target, and send a DSC call to it via the VHF radio without having to enter any MMSI information. And in both cases the AIS units will provide MOB alarms, AIS collision alarms, and in the Vesper case also do Anchor watch alarms.

Another AIS option is the Digital Yacht AIT3000 which has a built-in antenna splitter, so you just connect the VHF to the new AIS unit. The AIT3000 has WiFi, NMEA mux, and all sorts of stuff similar to the Vesper XB8000 but the built-in splitter is unique.

In any case, as of today, there are no VHF radios with built-in AIS transponders, and my educated guess is that FCC, SOLAS, GMDSS, and USCG regulations of various kinds are holding that back.

Exactly correct. I have a GX-2200 VHF with a GPS-equipped XB-8000, which feeds targets a B&G plotter over NMEA 2000 and to a Furuno radar over NMEA 0183, which also shows plotter-like data thanks to a heading sensor.



So that gives me separate GPS inputs on the plotter and radar via the AIS, and the VHF as a stand-alone. If the Vesper dies, the plotter has a built-in GPS.

AIS receive on the VHF, on the plotter via the Vesper, and on the radar via the Vesper.


The thing I do not do, by choice, is overlay the radar on the plotter. I prefer a stand-alone radar display for context, with the ability to show at discretion AIS targets and other data, like converging courses and time to collision, etc.

The set-up is geared less to integration and more to redundancy. I haven't even mentioned the sextant and the lead line!
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Old 15-11-2018, 10:44   #11
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

easy, because they want to sell it extra to make money.


Receiver only is in fact a bloody useless thing. Buy a cheap VHF and an excellent AIS transceiver like the Vesper Marine XB-8000 AIS Transponder with WiFi will be perfect.
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Old 15-11-2018, 11:17   #12
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

The issue with the AIS transceiver with the VHF radio is an operational and logical safety issue.
operationally- the AIS is divided between AIS A and B.
The AIS A model is 12.5 watts power transmits every 3-7 seconds with dynamic info and every 3 minutes with static info (boat name/length/voyage info.
There is an AIS B 5 watt transmitter that duplicates the AIS A specifics that is designed for permitted commercial vessels coastal.
Commercial required carriage of AIS is required to be a stand alone antenna/system from the VHF

Yachts generally use the less expensive AIS B.
AIS B is 2 watts power transmits every 30-70 seconds and static info every 6 minutes.

AIS B is toted by various sales as better with altitude (height) of the transmitter antenna - and is obtained via a splitter in the masthead antenna of the VHF. The splitter is supposed to prioritize the VHF but switches back to the AIS.

The discussion is fraught with misconceptions. Most important- the altitude signal gained by a 50' foot mast is lost in the 70' run of the antenna cable and three plus connectors (potential corrosion and signal loss)
The masthead vhf antenna is tuned to transmitting channel 16- (156.8 mhz) and not centered at 161.975 mhz (87B) or 162.025 mhz (88B) .So some efficiency transmitting lost.

Results are often debated- but commercial consensus is that most sailboats do not show until 3 miles cpa with a MMSI number (dynamic) and most power boats are 5-6 miles.
This suggests that the 3db whip (masthead sailboats) is not as efficient as the 6 db whip (generally on powerboats as longer and more stable) . as well, many sailboats with splitters installed are losing more signal than understood.

The AIS system is the greatest maritime communication device in recent history. It is only at its infancy. The USCG is already utilizing it to identify and replace fixed aids to navigation, local message information (bridge positions, obstruction, buoy off station messages , etc. ) and is experimenting with weather messages, local notice to mariners, and other traffic messages. So interrupting intentionally (by transmitting on the VHF) suggests more opportunities for lost incoming information cycles. This is particularly important when listening for a Man Overboard and coordination/reporting rescue on the same VHF.
The AIS PLB MOB units on the market now are becoming reliable particularly offshore. Just beware they are transmitting a "9" as a first string number- so older (<2014) plotters and AIS units may not be programmed to receive that info.

Last- a communication device designed to stand alone (transceiver- the plotter may be extra) - with the equipment expense being identical, why would a prudent sailor combine the systems thru a questionable antenna splitter that if fails, the antenna fails, the mast fails, the entire communication of the vessel is out of commission. Instead install a dedicated tuned AIS antenna 2 meters above the water and have peace of mind that others can see you in the most efficient manner.

USCG Navcen pages can help on details.
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Old 15-11-2018, 11:49   #13
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

I said the same thing about GPS in a VHF radio many years ago and now we have them available. It all takes time and a reasonable market. My prognostication is that in the future VFH radios will have it all, and in time all vessels will be required to have them under the guise of safety...every minimalist will not be happy.

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Old 15-11-2018, 12:35   #14
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

It is not difficult to design AIS class B functionality into a VHF radio chassis. 98% of the hardware is already in the radio now. About all that needs added is software and some low power parts.

The reported S/H solution requiring two antennas will not make a lot of people want to upgrade. Many people don’t upgrade purely for antenna logistics reasons.

It is also not correct that increasing height of antenna to get more range is a waste due to the longer cable. That can be easily disproven by math or a simple experiment. The power needed to reach the radio horizon is pretty low even for an antenna of 10 meters height. 2 watts is all you need. A typical radio outputs 25 watts which is not all going to be lost in a 10 meter cable.
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Old 15-11-2018, 12:37   #15
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Re: Why do VHF radios only come with a AIS receiver not a transceiver?

So after reading some of the responses, I contacted Standard Horizon and asked them if they had a radio coming. In short they just said “it is still in the design stage and no date yet in when it is ready”

Hello Mark:

Thank you for contacting us with your question. The GX6500 is still in the design stages and at this time we do not have a date of when to expect it. We do have the GX6000 available but it does not have the AIS transponder function built in.
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