COMMUNICATION SCRAMBLER SYSTEM
A scrambler system in which amplitude zero-crossings in speech are
encrypted at a transmitter by combination with a pseudo-random digital
sequence, the reverse process occurring at the receiver. The amplitude
envelope need not be encrypted, but if desired, can be encrypted by
combination with a further pseudo-random digital sequence. A higher level
of scrambling can be achieved in the transmitted signal by using the
conjugate of the amplitude envelope.
With a sequence bit rate of about two kilobits per second, there is no
increase in bandwidth requirements compared to the transmission of
unscrambled speech. Thus standard transceivers can be employed, and
pre-existing ones readily modified for scrambling and unscrambling.
Reynolds; John Spackman (Portsmouth, EN) |
The General Electric Company Limited
April 12, 1972|
Birmiel; H. A.