AIS misinformation, and a worry
I hate to be a scold, but an otherwise fine new article about AIS in Cruising World contains this flawed paragraph:
Once an AIS signal is received by the antenna, it’s sent to a black box that translates the data into NMEA streams that can be sent at 4,800 or 38,400 baud. The lower baud rate works with electronics suites still using the NMEA 0183 communication protocol; the higher baud rate works with proprietary networks, such as RayMarine’s, and devices using the more capable NMEA 2000 communications protocol.
Every AIS transponder and receiver I know of outputs the same way—NMEA 0183 data messages at 38,400 baud. The 38.4k speed rate is called NMEA 0183–HS (high speed) and is included in the current standard. As far as I know there is no AIS using the NMEA 2000 standard or a proprietary communications protocol, though the new Furuno receiver does do Ethernet in addition to 0183–HS and the junky NASA unit apparently filters out some AIS messages before it sends them down the 0183 pike (though NASA claims it uses N2K, God knows why).
I’ve heard a very ugly rumor that the Class B delay at the FCC may be something serious and long term. Can anyone elaborate?
NASA AIS Engine 2, as screwy as #1
March 18, 2008
New NMEA Combiner Concept
July 7, 2004
Now it’s the Si-Tex/Nasa/Nobeltec AIS receiver
October 18, 2005
More on NMEA-0183 and GPS?
March 14, 2004