FAA pulls funding for LAAS landing systems

"JJ" wrote in message
...
The LAAS correction uplink is in the 150MHZ area. It would have been
more susceptible to FM interference than a Localizer. Just another
little tidbit of info.

Wrong. The LAAS VHF Data Broadcast (VDB) is capable of existing on 108.00
MHz to 117.75 MHz (LOC and VOR freqs). The plan is to use VOR freqs (114.00
and up) until ILS freqs become available thru decommissioning (if it ever
goes that far.) Since the VDB is a D8PSK digital signal it is not
significantly affected by the interference from the FM band.


Bob Noel wrote:
In article , Javier Henderson
wrote:


except in for the problems with ILS in Europe...

What's the problem with ILS approaches in Europe? Frequency congestion?


yes. and interference from FM radio stations.

And multipath. Terrain and new high-rise construction around airports
creates multipath that puts "bends" and "noise" in the ILS path (it's an AM
system). Too much of either and you can't use it for CAT III.

MLS mitigates all three of those problems. There are 200 channels vs. 20
for ILS. It operates in the 5.1 GHz band so there's no high power
transmitters operating near it avoiding the FM broadcast interference. And
the use of a scanning beam instead of an AM differential signal greatly
improves multipath rejection.

Heathrow put in two new MLS ground stations and there are others scheduled
to be installed on the continent.

Gerry