What is Up with Logan's (Boston's Airport) Radar System

[Muddy]

I am amazed by the frequency and type of failures the air traffic
control RADAR at Logan Airport. The latest failure seems to be really
strange by the news descriptions. They said that it was creating
additional images of aircraft that weren't there in the combined IFF
and real RADAR image the controllers use. The alledged cause of the
problem was the antenna, but finding that took a couple of days.
Shouldn't a system like that find and isolate errors like that on its
own? I am assuming that the error was that there were ghost images in
the real RADAR image, that had no matching transponder in the IFF
returns. Can anyone explain what happened in engineering terms?

[Armin Doerry]

Bad cables and/or connectors will cause impedance anomalies that reflect
energy... This energy can bounce back and forth within the transmission
line and cause ghost targets...

In our radars, when we encounter anomalous range responses, the first thing
we look for are bad cables/and conectors....

Armin
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Armin Doerry

Post by Muddy
I am amazed by the frequency and type of failures the air traffic
control RADAR at Logan Airport. The latest failure seems to be really
strange by the news descriptions. They said that it was creating
additional images of aircraft that weren't there in the combined IFF
and real RADAR image the controllers use. The alledged cause of the
problem was the antenna, but finding that took a couple of days.
Shouldn't a system like that find and isolate errors like that on its
own? I am assuming that the error was that there were ghost images in
the real RADAR image, that had no matching transponder in the IFF
returns. Can anyone explain what happened in engineering terms?

[Muddy]

I worked in Military Embedded Test for a while, and the Radar, lots of
IR, one RADAR, I worked on would have quickly identified any gross
impedence change for sure, and most changes large enough to cause
ghosts. The effect of additional buildings would have been hard for a
moving Radar, but trival for a Radar in a long term fixed positions.
Few Planes hover for hours, and none hover for weeks at a time. In
addition, building don't spring up over night either. It would seem
theoritically trival, in engineering terms it might take a while, to
have a fixed RADAR identify problems caused by fixed objects. Now
ghosts caused by atomspheric conditions might be a little more tricky,
but if they presist for long, it shouldn't be a big deal. Of course
you have to consider the risk that a plane might have a non-functioning
transponder, so the simple method of eliminating ghosts isn't very
safe.

THe right way would be overlapping Radars nets, but that would cost
money, and we all know homeland defense money is never spent to address
real threats.