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(meteorobs) Radiometeors from ILS Beacons

Hi Paul,

Sorry to be the bringer of bad news, but the FAA's 75 MHz Instrument
Landing System (ILS) marker beacons are no longer available for radiometeor
work.

Below is a short excerpt from an analysis which I did in 1991 regarding the
feasability of setting up a short-range 6-meter system for doing meteor
scatter work.  This analysis was prompted in large part by the phase out by
the FAA of the suitable 75 MHz ILStransmitters:

"Airport ILS beacons also offered a promise for establishing a common
design for
receiving stations while also allowing more direct comparison of data from
different
amateur stations. However, several problem areas existed here also: (1)
Airports large
enough to have ILS systems are normally located near population centers, so
background noise could often pose a significant problem. (2) ILS  75 Mhz
beacons
utilize highly directional Yagi antennae, which "illuminate" only a small
portion of
the available scattering area, and were not pointed to the areas for best
meteor burst
with a receiver station. (3) Transmitter power levels were quite small,
usually 10-20
watts, at the lower limit for meteor scatter for this arrangement. Despite
these
difficulties, many meteor bursts were monitored using these transmitters,
especially
from Overdense trails, and the possibility did exist for the establishment
of a
continuously monitoring and recording station. [insert:  sucessful
experiments were conducted using these beacons by Bill Black (1983), and
Meteor Group Hawaii (Mike Morrow, George Pokarney, 1984-5)]

Recently, however, FAA regulations
(see 1991 FAA AIM, chapter 12, section f) have required the phasing out of
all older "high"
powered beacons, and most airports have changed to a new beacon system,
transmitting at 3 watts or less, below the level suitable for meteor burst.
When these
changes are complete at all airports, these beacons will no longer be usable."

From:
Richardson, J.E., (1991).  Analysis of a Short-Range Forward Scatter Meteor
Burst System." The American Meteor Society, Geneseo, New York.


As far as I know, the majority of airports had made the transition to the
new low powered systems by the early 1990's.  When I experimented with this
method in 1990 in San Jose, Ca, I found that i could detect aircraft coming
in on final approach quite well, but detected no meteors.

In a small irony of science, one of the primary reasons for the switch to
the lower powered beacons was to prevent interference with the 75 MHz radio
astronomy band.  

Take care,


Jim Richardson
AMS Radiometeor Project Coordinator
Graceville, Florida

richardson@digitalexp.com
http://www.serve.com/meteors
References: