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History Of The Computer; The
Emergence Of Electronics
By: Tony Stockill
The history of the computer inevitably includes the
development of electronics, we look at the explosive (!)
growth of electronics in the late 1930s and early 1940s.
If anything could be said in favor of war, it may be
that it speeds up the development of technology. Of
course much of that technology is employed in killing
people and destroying infrastructure, but there are also
things which could be considered beneficial.
Electronics was around in the early part of the 20th
Century, wireless, or radio, was in its infancy at the
time of the first world war. Radio broadcasting came
into prominence in the \'20s and 30\'s, Television
started in the \'30\'s.
The second world war, from 1939 in Europe, and a couple
of years later involving the USA, ended in 1945. Radar
(Radio Aid To Detection And Ranging) was developed from
early experiments, just prior to the war, in Britain and
Germany. There was rapid development in the field, and,
by the end of the war, Radar was being used in several
fields.
Aircraft Navigation - Using ground transmitters in sets
of 3, widely spaced, to give an aircraft using a
receiver a method of pinpointing its position. This is a
similar system to that used in gps today, substituting
satellites for the ground stations.
Targeting - A beam was transmitted from a Radar station
in England so that it intercepted a target in Germany.
An aircraft could fly along the beam, guided by signals,
dots or dashes, if it strayed off the beam, left or
right. Known as flying on the beam.
Interception - a series of ground stations around the
South-East coast of England, feeding into a central
control room, where their tracks could be displayed,
significantly assisted in the Battle of Britain (1940).
Airborne Interception (AI) - Developed towards the end
of the war, used a Tranceiver (transmitter/receiver) in
a night fighter to find a target in the dark, or bad
weather, and track it to within firing range.
Beacon - A tranceiver was located at the end of a runway
so that ground staff could guide a returning aircraft to
land in bad weather, this became more and more
sophisticated, developing into GCA or Ground Controlled
Approach.
Shipping - radar equipped vessels could track other
vessels in darkness or fog, whether peacefully or
aggressively.
Many other sytems were developed or initiated in that 6
year period. Knowledge of electronics, and what it could
be used for vastly increased. In parallel with the
development of radar, other fields of electronics were
also advancing, under pressure from the requirement to
improve the technology.
Long range guns on ships or in the field needed to be
aimed accurately. The calculations required in
ballistics to aim a gun so that you can hit the target,
or aim a V2 rocket so that it hits London from
continental Europe, are phenomenal.
This, then was the scene at the end of the war. We knew
how to tackle large calculations with speed, and we had
developed a new concept in electronics, Pulse
Technology. This is so called because radar uses short
pulses of high energy, for two main reasons.
1. The pulses can be coded. For example, in the
Navigation example we looked at, 3 ground stations
transmit a signal whose source needs to be identified.
One transmitter could transmit a series of single pulses
spaced say 10 milliseconds. A second could transmit a
pair of pulses at 10 millisecond spacing, and the third
3 pulses. A chart would tell the navigator where the
pulse sets were transmitted from, and the distances
obtained from the radar set used to locate the position
on the chart.
2. The power, or strength, of the signal. A continuous
radio signal, like a radio broadcast, takes a given
amount of power. However, a 1 millisecond pulse every 10
milliseconds, uses only one tenth of the power, on
average. So a radar transmitter can have a much greater
range for the same power. This is is especially
important in a primary (transmit and receive) radar
system, where we must detect the reflection of the
signal we transmit. Likewise a secondary (receive) radar
system, for example the navigation system above, will
have a bigger range. |
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