In the 1980s high power slowly tuning signals appeared on the
short wave broadcast band. The pulse rate was around 10 Hz.
They originated in the Sovjet union and were according to western sources
intended for military uses. The most natural guess from the point of view of a
physicist would be to interpret such signals
as a means to study all types of vehicles travelling in the earths athmosphere
such as in particular cruise missiles otherwise invisible to ordinary radar.
The choice of the short wave band means that reflections against layers of the athmosphere
makes it possible to obtain reflections from low flying vehicles and then
detect those signals after one or several reflections far away from where
that reflection took place. Furthermore, the choice of pulse rate is compatible
with the round trip time around the earths circumference. Since the reflected signals from
single vehicles are expected to be extremely weak and also can emerge on many different
locations, there are very good technical reasons for not using higher repetion rates.
If higher rates were used, weak signals from remote objects would be hidden by stronger echos
from nearby objects. I suggest that the choice of frequencies and pulse repetion rate is
motivated solely by a wish to obtain the maximum amount of information while retaining
the maximum discrimination of signal and background noise.
In my view this is a very obvious observation that anyone among the very skilled military
scientists can make and I feel convinced that they agree completely whether or not they would
openly say so.
I have repeatedly run across discussions about those signals where the technical motives
for the repetition rate wasnt mentioned while the coincidence with brain frequencies was
made an issue.
Since I haven't seen the technical aspect of the repetition rate explained well I feel
it needs to be said,
since it has been suggested that the choice of pulse repetition rate would have something to
do with mind control, the brain waves pulsating at about the same range of frequencies.
It is known from laboratory experiments
that ELF frequencies, extremely low frequency electromagnetic fields, can cause nausea and other
unpleasant symptoms. The brain waves lie in the ELF range of frequencies. The mentioned
short wave pulses have frequencies of, say 10 MHz, while their repetion rate numerically lies
in the ELF range. This however is different from real ELF waves. If there is any
low frequency effect coming from the short wave pulses it would be through thermal effects.
Through weak heating of the target.
Some scientists have suggested that the wood pecker signals might have
detrimental health effects.
I haven't looked for any quantitative discussion about it and dont wish to enter the debate.
However I do think the above discussion about the technical motive for the choice of repetition
frequency is a strong argument for suggesting that if there are such health effects they
come as a side effect. In the 1980s the american military, in possession of the cruise missile
technology, wouldn't like this sovjet beyond the horizon radar to be successful and therefore had
natural reasons for putting the emphasis on such potential side effects.
The sovjets on the other hand probably didnt feel any need to clarify the matter.
It is in the nature of these things that neither side seems to be very critical of the other
and even dont seem to mind being demonized occasionally. All openness tends to show that
there is an ongoing interplay of matching entities, each side developing measures and