Analogue Speech Security Systems

Speech is probably the most fundamental form of communication available to us and our society has become highly dependent on our modern, fast and accurate means of transmitting spoken messages. Usually the main aim of communicants is merely to trasmit a message as quickly, accurately and cheaply as possible. There are, however, a number of situations where the information is confidential and where an interceptor might be able to benefit immensely fromt he knowledge gained by monitoring the information circuit. In such situations the communicants must take steps to conceal and protect the content of their spoken message. Of course, the amount of protection will vary. On occasions it is sufficient to prevent a casual ‘listener’ from understanding the message but there are other times when it is crucial that even a determined interceptor must not be able to deduce ti.