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Author Topic:   USCG NAIS Base Station Testing October 2014
jimh posted 10-17-2014 10:55 AM ET (US)   Profile for jimh   Send Email to jimh  
The Coast Guard of the USA has announced that in a few days, on October 21, 2104, its National Automatic Identification System (NAIS) base stations across the USA will be transmitting AIS messages as part of a test.

If you have an AIS receiver and have it connected to a chart plotter, it may be interesting to receive these AIS base station test messages and observe the behavior of your receiver and chart plotter during the test period.

The test period is from 1100 to 2215 UTC, beginning on the hour and lasting for up to 15-minutes. AIS messages are described in

During the testing period, messages 8, 25, and 26 will be sent. The USCG advises any mariners who can decode these messages they should ignore them. If there is any negative effect from this test on your navigation equipment you should contact the USCG Navigation Center at 1-703-313--5900 or at via email to <>

The AIS Base Station Messages are typically not particularly well known to many existing recreational-grade navigation displays or software that decodes AIS messages. Presently most USCG NAIS stations are sending just AIS Message ID 4, "base station report." Even this basic message is often not decoded or interpreted by navigation hardware and software at the consumer level. A basic test of your AIS hardware and software regarding AIS base stations can be made by checking to see if the position of the base station is plotted on your electronic chart.

jimh posted 10-17-2014 11:03 AM ET (US)     Profile for jimh  Send Email to jimh     
There are two segments of the user system in receiving an AIS message:

--the receiver hardware and its data link output, and

--the navigation hardware or software that will interpret and display the message.

If you have an AIS receiver, you may be able to capture the data link output from the receiver during the test period to see if your AIS receiver was capable of properly receiving the transmission and sending the data payload on its data link.

If your AIS receiver is connected to an electronic chart display and information system (ECDIS), you can also test to see if the navigation system properly handled the test message data.

If you capture the AIS receiver output, you could also test the AIS message output with an on-line AIS message decoder. Here are a few decoders: is able to decode AIS message ID 8 (Binary Data Broadcast) is able to decode AIS messages with ID 1 to 26.

dfmcintyre posted 10-20-2014 06:46 PM ET (US)     Profile for dfmcintyre  Send Email to dfmcintyre     
Jim -

Would the sites like > show these signals?


jimh posted 10-20-2014 08:08 PM ET (US)     Profile for jimh  Send Email to jimh     
MARINETRAFFIC.COM is already showing the location of USCG NAIS base stations sending AIS Message #4. I don't know what they'll do when these stations send a test message of #8, 25, and 26.

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