Re: Mathemagickal Dullskuggery

On Sunday, in article
<e9cs30$bqq$1$8302bc10@xxxxxxxxxxxxxxxx> adv@xxxxxxxxxxxxxxx
"Hamish" wrote:

"Oz" <Oz@xxxxxxxxxxxxxxxxxxxx> wrote in message
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Oh No <notI@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> writes

.
Most, almost certainly all, ranging will be done by time of flight using
pulses on the wavetrain.

In modern radars it is no longer usual to measure the transmit to return
time to measure distance. It is very power demanding
in that the transmitted pulse must contain sufficient energy to be
detectable above noise at reception. A lot of power in a short duration
pulse
is expensive and can cause interference with nearby electronic equipment.

It is more common to transmit a much longer tx pattern contimuously and use
correlation techniques to reconstitute the range information.
One additional advantage is by dropping the instantanious signal level
below noise it can be difficult to lock into the source.
Also in a Wireless World article many years ago there was a project to have
a radar display of incoming aircraft to a commercial airport by receiving
the transmit pulse and then the returns fom the aircraft.

Probably not to be encouraged in these sensitive times.

One idea I've seen, admittedly in a rather science-fictional
environment, is to look for holes in the microwave background.

--
David G. Bell -- SF Fan, Filker, and Punslinger.

"I am Number Two," said Penfold. "You are Number Six."
.

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