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RE:(meteorobs) 24h Draconids monitoring



At 11:31 PM 10/06/98 -0400, Tom Ashcroft wrote:

>Hi Werfried,
>
>I will attempt to monitor but it looks like I will have to reconfigure my
>radio meteor array as I haven't monitored in awhile.  When I started
>forward scatter monitoring some years ago I had at least two to three open
>frequencies on the local FM dial to work with 24 hors a day. Now nearly all
>the 88-108 MHz frequencies are regionally occupied during the daytime. At
>night it is easier to observe because one or two frequencies open up when
>local college FM stations go off the air at midnight and don't come on
>again until sunrise or so. I will see what I can do in any case. 

Tom, have you tried listening for television transmitters, either the
amplitude-modulated video carriers or the frequency-modulated aural
carriers? And, are you using a directional yagi antenna? If so, do you have
it elevated or pointed at the horizon? The difference will be that if it is
slightly elevated, you will probably obtain some additional directivity
because you will be tilting the antenna's pickup pattern away from
transmitters that are located on your horizon. In addition, by tilting the
antenna upward, you will be listening for meteors that are *above* your own
horizon, and thus are closer to your station; this has the added benefit of
reducing the signal strength loss because the distance from your antenna to
a meteor trail and down again to a far transmitter becomes shorter. For
forward-scatter, signal strength is proportional to the square of the
distance so that atmospheric loss can decrease considerably rather quickly.

You might also try the FM band while elevating your directional antenna;
the elevated pickup lobes may shift far enough over a close-in transmitter
that it does not normally interfere with listening for meteor-scattered
signals.

My last suggestion concerning the FM band is that you make certain that
your receiver is not picking up the same station at two points on the dial,
which is caused by a design deficiency in the receiver to cut costs. If so,
then you should try to use a tunable filter to reduce the number of
stations that you can hear at one filter setting.

I have also heard of folks listening for the VOR beacons at airports which
are located at the very top of the FM broadcast band from 108 to 116 MHz, I
believe. Of course, you would have to check that the beacon of interest is
left running 24-hours!

Clear skies,

SteveH
Shrewsbury MA

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