Jim, Mal, LF group
We have a great opportunity here for doing some valuable research into
propagation.
To my knowledge no one has measure fading from a single source at different
locations at the same time, and been able to correlate the results.
Analysis of the fade timing, depth, measured against radial distance is
possible with WSPR or similar systems. The simultaneous measurement fading
at different locations will give interesting data on the movement of the
effective reflection area and its relative strength to the groundwave. The
effects could even plotted as a signal strength animation on a map given
enough measurement points.
For Mal's benefit, it needs to be pointed out that the strength of WSPR is
not in multiple transmitters, but multiple receivers.
That being said, the more beacons there are, the more data we can collect.
The occupied bandwidth for WSPR is very small, and based on the relatively
low level of other activity is very good use of the band.
Part of the 500KHz experiment is to see how well the spectrum can be used.
Any operator that insists that the band should be devoid of any other
signals while he or she makes a QSO (be it CW sent by hand, RTTY or any
number of modes) is at best misguided, at worst selfish, or a poor operator,
or one incapable of using readily available technology to keep the receiver
from being as wide as a barn door.
I can quite happily copy the CW signals from the various beacons up around
505KHz, with the stronger ones only a few tens of Hz away. I would expect
we all can. I see no problem in having many more beacons in the band should
the experiments warrant them.
We need as many WSPR receivers on as possible at one time to gather data.
For those who have not got equipment that is easily dedicated to this,
perhaps we can set up some WSPR activity periods.
For those wishing to set up a dedicated WSPR receiver, one very simple
solution is what I use for my grabber. A Softrock lite on 500KHz, a simple
ferrite antenna and a PC. The permanent internet connection is a nice to
have, but not necessary as 'logs' can be uploaded later.
My WSPR receive system is now integrated into my grabber centred on 503.5.
It uploads real-time to the database.
I will retune to listen to the USA WSPR transmissions as required, unless I
can find a way of running 2 instances of WSPR at the same time on different
audio input frequencies, which may be possible with Virtual machines.
Lets hope for some good propagation.
I am in the process of putting together a transmit mixer and driver for my
linear system, so I will eventually be back on with all modes available, and
will be able to transmit WSPR
Mark GM4ISM
----- Original Message -----
From: "James Moritz" <[email protected]>
To: <[email protected]>
Sent: Sunday, December 21, 2008 12:16 PM
Subject: Re: LF: Re: 500kHz WSPR Beacon
Dear Mal, LF Group,
The bandwidth occupied by a WSPR signal is around 6Hz. Even if every
station
with a licence ran a WSPR beacon on 500k, only a small fraction of the
band
would be occupied. Practically, the total bandwidth used by all beacons
would be limited to 200Hz, since this is the bandwidth of the receiving
software. So the total bandwidth occupied by such beacons could hardly be
greater than a single CW signal.
Cheers, Jim Moritz
73 de M0BMU
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