For a couple of months now, I have been noticing ghost ships appearing in
the area covered by node 157.
http://marinetraffic.com/ais/default.aspx?zoom=8¢erx=-59.63044&ce...

These ghosts would appear line-astern from other valid ships, and would
just show a MMSI. Trying to track the MMSI using sources other than MT do
not show any valid listing.

When I initially saw them, I noted that there was a multi-nation military
exercise in the area, and wondered if they were not-so-discretely following
regular marine traffic. Quickly dismissed that idea... :-)

These ghost reports lie precisely on the valid vessel's track. For example,
at this moment, a valid vessel with MMSI= 304198000 is being tailed by two
ghosts, MMSI= 297803912 and MMSI= 304087044.

What could be causing this? RF front end overload on the receiver? fault in
the AIS receiver/decoder, or problems with Internet or MT?