Re: [IRCA] India to Illinois on 1566

["Bob Foxworth" <rfoxwor1@xxxxxxxxxxxxxxx>]

> The bearing to Nagpur is about 13 degrees..I wonder just how much of
this
> transpolar path is in daylight at this time of the year !!


> > But today there was some skip - I logged AIR Nagpur on 1566 kHz!
That is a
> > very
> > big deal in my location.
> >


> > Nagpur is right smack dab in the center of India, which is probably
why it
> > was
> > chosen for a 1000 kW transmitter, approx. 79 E, 21 N. 2035 CDT =
0135 UT,
> > or
> > 0705 IST, i.e. close to SR at the transmitter and SS at the
receiver.
> > Perhaps
> > someone will check out the grayline at that time on Summer Solstice
to see
> > what
> > the path looks like in those terms (Glenn Hauser, OK, DX LISTENING
DIGEST)


I recall even back in the GPN days of long ago, some discussion
of paths not necessarily taking a straight line along (over) the
earth's surface but rather bending in an arc. I now think it's possible
that a signal could follow an arc along a grayline path. The time
of day sounds possible for this to happen, but I am not nearly
an expert in this. MW DXers have limited options to determine
the direction from which a signal arrives, but I have heard
reports of hams with directional LF antennas reporting signals
coming from unexpected directions, not from the GCP (compass)
path. And in July the sun is already noticeably moving away
from its northern-most solstice approach to 23 degrees north.

I spent some time listening to Nagpur 1566 when I spent some
time in Tamil Nadu and Kerala states a few years ago. The
limited details he posted seem pretty valid to me, as far as it
goes. I always thought this one was directional towards the
north and northwest, perhaps to reach New Delhi and maybe
Pakistan, and where I was (to the south) would have been off the
back end, as it was never really strong for me in Madras. If
so, then the ERP towards NAm is even greater than just
power alone would indicate. But here I am just speculating.

India can be somewhat secretive about details of their
radio infrastructure. Maybe someone can find their site on
Google and do a tower count, but I have no idea where
exactly to start looking. Some fellow in Europe posted
the coords of the VLF DHO38 site, on a LF list, and upon
zooming in, (in maps.google.com) you could see the
red/white banding on the towers. This may be a similar
case.

One of the big problems with understanding this kind of
mechanism is the random haphazard nature of data collection.
If more people had systems such as Nick Hall-Patch uses,
to log and record carrier levels daily, we might find that
receptions of unexpected signals could well happen more
often than anyone expects. Remember the number of times
the Chinese FS station in Xinjiang was heard (1525 kHz)
in the northeast US, probably a half dozen times in my own
experience. The problem is that if propagation happens
only a couple percent of the time, and DXers are listening
to the correct frequency only a couple percentage of the
time, the probability of success is the product of those
numbers, which is a very small number. An automated
signal logging receiver would then make the probability
equal to only the propagation condition, as I see it.

So in short, yes, I believe it could happen, but very
infrequently.

- Bob                     sent 0923 edt




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