Re: AIS Position Error?

I beleive I have read somewhere that professional systems are able to
utilize AIS targets as input for target tracking on a conventional radar
system/screen. Has anyone been able to test anything like this on
consumer equipment? Would it even be technically possible? As Paul
mentiones in his post above it can be somewhat dangerous to rely only on
AIS data, even if one is not using Pauls own software ;)

Cheers
david

David,
do you mean something like this? see the pictures here:
http://uk.pg.photos.yahoo.com/ph/dbadvies/album?.dir=1449re2&.src=ph
As you can see, AIS targets are displayed on the radarscreen of the
raymarine E80. You can activate an AIS sourced CPA alarm together with
a marpa alarm.

Experiences:
To be honest, I most of the time use radar overlay (on a Navionics map)
during our crossing from the Netherlands to Norway. I still use rader,
because:

First: Keep in mind that fishingships don't use AIS yet. So if you only
look for AIS targets, you will miss some importent fishing ships. These
ships always seem to change course suddenly or at the wrong moment.

Second, AIS data is not always correct. For example, If a ship is not
moving, compass data can be wrong when its derived from a GPS. In the
harbour of Rotterdam, there are several ships which are not positioned
right. (bow to the water instead of lying parallel to the kay). What
also happened during our crossing is that AIS targets where lost while
others stayed. Happened in 2 occasions. I guess somebody did a
reboot(?) We also met a ship which was according to the ais data "under
sail" but it was a huge tanker at 20 knt speed. (BTW, I have a 2
channel receiver)

Dirk

.

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