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What is SPSM?
Necessity being the mother of inventions, EMI never stopping is behind this one.
SPSM is a new simplex mode of
Lightning Radar using only one antenna to find the lightning strike.
Using the coined phrase "Synthetic Propagation" as one of
the two radar stations, normally used, in the triangulation method of
lightning detection.
A good understanding of the
normal LR method of detection is required to understand this mode as its
the same in all but one respect. Please take a read on this page of
the original LR page
if you need to better understand how it all works.
How It Works
In the picture at the
right, the SPSM station is CPU 2 and has no
antenna connected.
Notice on the spikes, of the
Left and Right channels, the amplitudes are different on adjacent pulses.
The ratio of the amplitude tells LR the angle to the strike. If they
are equal then its 45 Deg regardless of their amplitudes.
So to make a synthetic angle,
we need to send LR these same type signals in place of the Antenna via our
own generator of angles.
When those pulses are applied
to LR's channels, it will then produce our next needed product, which is
the time of the strike. This gets recorded by LR when the generator pulses
appear.
Now here is where the secret
to the whole thing occurs. Since with no antenna on our station, we
have to depend on the other station to announce the strike. What we
do is scan angles and generate the time we were there, in the hopes that a
strike did occur in the window of allowances while we were there
looking. Then the two stations compare notes on strikes
available, for possible agreement. If were lucky some do coincide with the
correct time and angle. If they do then we have the same thing we
would have had with antenna signals telling the same thing. This has two
advantages over a second antenna. One our signal is very clean
indeed. Two we always have prefect propagation to the strike, star
wars style! One down side is the fact that scanning for strikes wont
produce as many strikes as direct reception of the signal. However
it can produce strikes that might be out of range of the #2 SPSM station
at the time. Remember every strike is off the antenna of the station
your connected to, since yours is not even connected! Therefore this
could be an excellent way of finding a stations antenna
pattern.
The Generator of angles needed for
this mode is discussed below.
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