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Voice Gretag GC-104 → ← GC-101
Speech scrambler
Gretacoder 103, abbreviated GC-103, is a telephone scrambler, sold in
the early 1980a by Gretag in Regensdorf (Switzerland).
Contrary to most other Gretag encryption devices,
the GC-103 was not manufactured by Gretag, but by
Telsy in Italy.
It was sold by Gretag as an OEM product [3].
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The device is based on the principle of the
voice scrambler.
This makes it less secure that true digital encryption, but offers the
advantage that the scrambled signal stays within the bandwidth of the
telephone circuit.
The device has two modes: time domain and
two-dimensional scrambling.
The latter uses a mixture of time domain and frequency domain scrambling.
The current mode is determined by the selected key.
A total of nine keys can be preset and the rotary selector at the center of
the front panel is used to select the desired key compartment.
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The device is connected between a regular telephone set and the
analogue telephone line (POTS).
It is identical to the
Telsy TDS-2004. For further information
and additional photographs, e.g. of the interior, please refer to our
page about the Telsy TDS-2004.
The GC-103 is compatible with the Gretacoder 104
– also known as the GC-104 –
which is the military variant of the device. It was also built by
Telsy
(as the TDS-2004M)
with whom Gretag had a very good relationship [3].
➤ More about the Telsy TDS-2004
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© Crypto Museum. Created: Friday 21 June 2013. Last changed: Wednesday, 21 August 2024 - 06:25 CET.
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