[PUP] AIS pitfalls

[Dave Cooper]

<John wrote: Actually, the FA-150 is a transponder... our buddies track us
via AIS when we are in the area long before they can raise us on VHF. Which
I find interesting given AIS uses VHF as well.>

Sorry I thought the FA-150 was just a receiver..my mistake.

The 3 GPS's in their 38' high location must have quite a ride ;-)

The reason they can see you when you can't reach them via VHF even though
you have 25 watts vs. the 4 of the transponder is due to the wonderful world
of digital transmission. It can get thru as it only looks for thresholds vs.
needing receive the full modulation of voice. Sort of like why Morse code
could always out do voice.

One of those GPS's must be dedicated to input the location, speed and
course...at least according to the spec. The other two are most likely the
differently pair to determine the ships heading.....hope you have a compass
as a back-up when it goes dark ;-)

So I must ask how you know what you are transmitting in all of the data
streams? Many of which most folks can't see...yet.

Have you received any Class B signals yet? Does your FA-150 have the
software to pick them up and display there complete data or does it leave
missing files without the word "missing".

You'd be a good guy to have around so I could talk to someone who can see me
and might actually be willing to talk back about the AIS. Not like the
Master of the Tropic Palm who basically "hung up" on me today. Bet we'd both
learn a lot more about each others units and what the ranges are :-)

And we haven't yet even got into the safety messages and DSC distress
messages it can deal with......a much more powerful tool than the current
VHF DSC, IMHO. It also has a much wider range due to the all digital nature.
So if you have a distress then instead of 10 or perhaps 15 mile radius you
have the radius of the AIS transponders signal...

Thanks for the correction :-)

As always YMMV

Cheers

Dave & Nancy
Swan Song
Roughwater 58
Caribbean Cruise '07