[HCDX]: Fw: Use your SW radio to monitor Nov 17 meteor storm (Reply from rec.radio.shortwave)

["Mark Veldhuis" <dx@xxxxxxxxxxxxxxxxxxxxxx>]

David W. Knisely <dk84538@xxxxxxxxx> heeft geschreven in bericht
<3648D42C.4A1C@xxxxxxxxx>...
> Hi there.  You posted:
> >
> > Meteors crashing into the upper atmosphere  leave an ionized
> > trail that can reflect radio signals in the upper HF and VHF
> > regions. The biggest meteor storm in 33 years will happen on
> > November 17, peaking around 1900 UTC.
> >
> > You can use your shortwave receiver to monitor these
> > impacts.  Select a shortwave station near you.  I would
> > prefer a station west of you that is beaming east.  You
> > should be inside the skip zone of the station for good
> > results.  (The skip zone is the region between the outer
> > edge if the ground wave and the place where the first
> > ionospheric reflection returns to earth.)  If you are not
> > totally in the skip zone this can actually help as will be
> > noted in an example later.
> >
> > Monitor signal strength.  Each time a meteor strikes the
> > upper atmosphere a temporary reflection will occur raising
> > the signal strength from the station you are monitoring.
> >
> > If you have some direct signal available from normal
> > ionospheric scattering, you may be able to duplicate an
> > interesting observation I made during the 1950's.  I was
> > monitoring a 17 MHz Voice of America transmission beamed to
> > Europe from Greenville, NC.  I was located on Long Island
> > New York inside the skip zone but with sufficient signal to
> > hear it easily.  I heard random heterodynes that would begin
> > at a high audio frequency and drop to near zero over a few
> > seconds.
> >
> > I later figured out that I was hearing heterodynes caused by
> > the meteor shower.
>
> There are a few problems with this.  For one, standard shortwave radio
> frequencies (well under 30 Mhz) are not the best ones for monitoring
> meteor scatter.  30 to 70 Mhz is better (Ionospheric scattering is
> minimal there), and very good results are also possible using FM
> broadcast frequencies.  There are enough stations on the FM band in the
> U.S. so that it is unnecessary to choose a particular station (just pick
> a fairly blank spot and listen for a while).  VHF Radio navigation
> beacons can also work here, but you need a very sensitive receiver and a
> good antenna, since they don't put out much of a signal to begin with.
> The meteor trails which actually do the scattering are not able to cause
> significant doppler shifts over the time they exist, since they are are
> formed in the atmosphere as the meteoroid burns up (becoming part of the
> atmosphere) and thus are not moving at the same speed as the meteor.  In
> fact, those which manage to survive for more than a few seconds often
> move quite slowly in response to upper-level atmospheric winds.
>    Two, the peak of any possible meteor storm will probably only be
> detectable in the Pacific basin and eastern Asia, since at 1900 UT, much
> of the rest of the Earth will be facing away from the incoming meteor
> stream.  We may get meteor scatter rates of from 10 to 50 per hour
> elsewhere, although there is a small chance a random place on Earth
> might experience a storm.  Good luck on the 17th.
>
>
>
> David Knisely  KA0CZC  dk84538@xxxxxxxxx
> Prairie Astronomy Club, Inc.  http://www.4w.com/pac
> Hyde Memorial Observatory, http://www.blackstarpress.com/arin/hyde
> ************************************************
> *  Attend the 6th Annual NEBRASKA STAR PARTY   *
> *  August 7-14th, 1999  http://www.4w.com/nsp  *
> ************************************************
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