How often does the AIS 600/800 transmit ?

[baz]

Subject: How often does the AIS 600/800 transmit ?

From using the MarineTraffic's vessel tracking display and clicking on the vessel's speed change points it appears to me that the frequency of transmissions is from 1 minute to 3 minutes.

I would assume (need to read the AIS 800 manual I suppose) the transmission frequency is a constant as set by default when the unit is initially configured via software.

Does anyone know what the default transmission frequency is; that is, the time between the unit transmitting its position, speed, etc ?

 

[JamesTXSD]

I think you may be confusing an app (Marine Traffic) with the function of your AIS transceiver. Your AIS should be transmitting continuously. The Marine Traffic app updates periodically, and the update may be historically off by 6 minutes or more... something to consider when the traffic (or you) is moving fast.

 

[baz]

Yes... I agree that my method for trying to obtain how often AIS 800 transmits is not in any way accurate.

Garmin has told me the Tx is periodic and not continuous. This makes sense to me as continuously transmitting surely consumes electricity which may be in short supply! They also told me the periodic transmission can be configure with software, but were unable to tell me what the default 'period' was.

 

[Chimo]

Great question Barry.

Check your manual but I believe the 800 is still a class B unit, correct me if I'm wrong please.

This from Milltech marine website https://www.milltechmarine.com/faq.htm#a6 , usually a reliable source.

"Class B AIS transponders also provide static vessel information every six minutes however the information only includes:
MMSI
Radio call sign
Vessel name
Length and beam of vessel
Type of vessel
Position updates for Class B transponders are broadcast less often than Class A transponders. Vessels going less than 2 knots transmit position updates every 3 minutes while vessels traveling more than 2 knots transmit position information every 30 seconds.
For this reason it is recommended that you consider purchasing a true dual channel AIS receiver if you plan to use the AIS receiver in an area where Class B transponders are in use."

So you and other class B units would be transmitting every 30 seconds traveling more than 2 knots. The update delay can easily be seen if you have radar overlay and watch the gap between the radar reflection and the AIS position as it updates periodically. It's especially noticeable with medium/high speed vessels, say 30 knots+.

 

[baz]

Chimo: Thanks very much for that information..... very useful. 🙂

 

[ixlr8]

The Garmin web site for the AIS800 does say;
" 5 watts of transmit power with Class B/SO provides faster positioning reporting than ever before¹ "
" ¹When cruising above 14 knots "
No indication what the "faster rate" is.

 

[Red Fury]

I just sent my 600 to the factory to have my old Boats US MMSI removed from it. Had to do this to be able to put in my new FCC issued International MMSI. While I was in the software reprogramming the unit I noted the location transmission frequency was set to 3 minutes. Don’t know if this changes as speed increases. I did time the transmissions at home on the trailer and it was exactly 3 minutes. I may plug the computer back in while underway and watch what happens.

 

[baz]

Bryan: This was informative..... wonder if AIS 600 and AIS 800 are the same wrt software configuration .... suspect they are as same software is used for both units AFAIK. Thanks... 🙂

 

[Chimo]

I just sent my 600 to the factory to have my old Boats US MMSI removed from it. Had to do this to be able to put in my new FCC issued International MMSI. While I was in the software reprogramming the unit I noted the location transmission frequency was set to 3 minutes. Don’t know if this changes as speed increases. I did time the transmissions at home on the trailer and it was exactly 3 minutes. I may plug the computer back in while underway and watch what happens.

Hi Bryan, If your trailer was doing less than 2 knots in your driveway that would tie in with what was mentioned for a class B device. Is your 600 a Class B?