Digital voice protection system and method

Abstract

A digital voice privacy electronic communication system and method provides protection for an information signal. Either a clear voice signal or a scrambled digitized version of the voice signal is selected for transmission. At the receive end of the system a determination that a clear voice signal or a scrambled signal has been sent is made. This information is used to automatically switch the clear audio signal if present to an output circuit or to switch to the output circuit either a regenerated version of the scrambled signal or an unscrambled version of the information signal. The switching is done automatically so that a user does not have to manually select the proper receiver mode in response to reception of a signal, that is, whether the received signal was a clear voice signal or a scrambled signal. At the transmitter the information signal to be scrambled is analog-to-digital converted and the digital signal is then put into a scrambled form. The scrambled signal may be then processed through base stations, repeaters, satellite receivers, etc., while still in the digitally scrambled form, thereby providing a high degree of protection for such a signal. A receiver may regenerate, or reshape, the scrambled digital signals or the signal may be unscrambled in the receiver depending upon whether the receiver is part of, for example, a repeater system or is a terminal destination for the signal. The digital privacy system of this invention may also be utilized in signal voting systems, either analog or digital, while still maintaining, if necessary, the secure format of the scrambled information.