Encoding and decoding apparatus for the protection of the secrecy of communications

摘要

The apparatus comprises an encoding circuit and a decoding circuit for electrical signals included within a predetermined frequency band, with operation enabled in a complimentary manner by electronic switching means (4, 36). The circuits comprise memories (22...25) for temporarily storing consecutively received portions of the electrical signals and means capable of enabling the operation of the memories for consecutively storing said received portions via an input switching means (4) and for sending the stored portions, in a different order, to an output switching means (36). This apparatus can be installed easily and rapidly and is easy to use directly in a telephone line or in a radio link. <IMAGE>