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Transmissions to collect clandestine information behind the
enemy lines was one of the main targets of the clandestine
warfare. Therefore, its efficency was improved only upon the
surgence of radio as a long distance transmission mean. Thus,
it was used largely during the WWII when the countries involved
in the conflict started in working hard to develop 2-way radios
to operate in several communication modes in in order they
could meet such stealth purpose.
In this way in order to develop the most reliable apparatus'
concept, engineers concentraded their efforts in several logistical
and operational features as follows:
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FEATURES
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CONSIDERATIONS
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COMPACT AND STURDINESS
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Mandatory due to the several transceiver
transport and usage conditions.
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TRANSMISSION MODE
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Generally it was used Amplitude
Modulation radiotelegraphy instead of radiotelephony;
as while in the first the transmitted signals needs
bandwithd of 0,2 KHz only, in the later it requires
minimum of 6 KHz.
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FREQUENCY RANGE
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Due to the distance involved in
between the home station and the portable transceiver
were higher than 2000 km frequency either considering
the quality of the ionospheric radio propagation waves,
the frequencies suitable for such coverage distances
ranged from 3 to 8 MHz.
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TRANSMISSION POWER
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Very low transmistting power in
between 1 to 10 Watt was chosen due to the compactness
and sturdiness of the apparatus as well as it also contributed
somewhat to avoid radiolocation by the enemy radiogoniometry
stations by reducing the generation of ground waves.
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ANTENNA
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Considering the transceiver had
a very low power transmitter - 1 to 10 Watt -, it required
a very sensitive and reliable antenna allowing radiation
patterns from 2 to 4 Watt even considering operation
in a desguising conditions.
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The radio transceiver frequency transmission should
be fixed with absolute precision using Quartz crystal
filters. It was mandatory either for the precise short
duration of the pulse transmission as well as to to
avoid radiolocation by the enemy radiogoniometry stations.
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POWER SUPPLY
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Sturdy. Stable and multiple use,
allowing the apparatus to be operated either in DC as
well as in AC since the outcome of the transmistions
were duly related with the apparatus operational flexebility.
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Instructions printed in military radio manuals for abandoned
material in combat zone
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