(meteorobs) Radio meteor detection on DTV frequencies

Jay Salsburg jsalsburg at bellsouth.net
Thu Oct 18 22:59:38 EDT 2012


Hello Paul

It appears as though you are applying one of those new TV Tuner Dongles to
receiving Back Scatter Meteor Reflections. Since I am familiar with these
Dongles, may I make some assumptions? I assume you are using an adequate
Antenna tuned to the frequency you want to receive, that antenna is pointed
at an angle above the horizon at the optimum elevation, and the transmitter
you are using for back scatter is at least 50 or miles away, that is, if the
antenna of the transmitter is not high above the ground on a tower. The
optimum distance of a transmitter of high power over the horizon is at least
farther away than 50 miles and less than 350 miles, unless it is very
coherent as a CW Beacon would be. Some transmitters may be too close at 50
miles because of their height above the ground mounted on high towers
together with very high power. The farther away the Transmitter, the less
interference from Aircraft you will experience, but the bigger antenna you
need.

I assume you are tuning the Dongle offset from the center tuning frequency
so its Zero IF frequency is a reasonable distance in frequency form the
signal of interest so as not to receive the noise from the Dongle's Zero IF
Carrier.

I suggest experimenting with SDRSharp, a very stable and useful free App for
SDRs.

-----Original Message-----
From: meteorobs-bounces at meteorobs.org
[mailto:meteorobs-bounces at meteorobs.org] On Behalf Of Paul Goelz
Sent: Thursday, October 18, 2012 6:09 PM
To: Meteor science and meteor observing
Subject: (meteorobs) Radio meteor detection on DTV frequencies

Folks,

I have been playing with a low cost Software Defined Radio using a
$20 digital TV receiver USB dongle.  Poking around the local DTV frequencies
looking at a 2MHz swath, I noticed that there was a significant residual
carrier even though the transmission is digital.

So today I tried using the carrier of a digital TV transmission to detect
meteors.  I'm near Detroit, and listening on the carrier frequency of each
unoccupied channel I found one at 192.310 MHz (tuned to 192.309 USB) that
seemed to have a bit of flutter on it (as opposed to a steady tone on some
others that could be leakage from local cable TV).  Plotting it for a while
in Spectrum Lab showed quite a few airplanes but no meteors (yet).
Understandable because the airplanes were weaker than they are at 55MHz.
Assume the meteors are as well at that frequency.  And the antenna is a 2M
ham antenna, so it is nowhere near optimum for 192MHz.

But this is progress.

Paul

Paul Goelz
pgoelz at comcast.net
Rochester Hills, MI
www.pgoelz.com 

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