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Voice encryption unit
The TS-500 is a rather simple portable voice encryption unit, introduced in
1976 by Telsy in Italy. It is one of the first in a range of
voice encryption devices, after the company started in 1971.
Similar devices were also sold as OEM products, e.g. the
Teltron SP-810.
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The image on the right shows the front panel of a typical TS-500 unit.
It only has one switch, that is used to select between clear and encrypted
voice. No other controls are present.
The cryptographic key is no more than a small PCB with a labyrinth
of tracks that is inserted into a slot at the front of the unit.
In the image, the key-card has been extracted from its slot.
The card is symmetric (i.e. it can be inserted upside down) and is extremely
easy to copy. Furthermore, it allows only a limited number of combinations
to be made.
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Despite the simplicity of the key card, the actual electronics
are rather advanced considering the unit's age.
The TS-500 contains two PCBs that are easily revealed by removing the
cover. They are mounted back-to-back, so that the components are
immediately visible. The Logic Board
contains all digital components, whilst the
Audio Board contains the analog components.
At the heart of the system are two FX-209
Adaptive Delta Modulation chips,
manufactured by CML in the UK. One is used as an encoder and the other one
is the decoder. Analog speech is digitized with such a delta modulator,
after which digital encryption is applied.
The TS-500 was followed in 1978 by the TDS-2000
series full-duplex voice encryption devices.
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© Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Sunday, 04 March 2012 - 15:06 CET
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