Teletype mixer apparatus for coding and decoding

In a teletype communication system, apparatus to cipher input teletype signals prior to their transmission wherein the input teletype signal represents a single character by a predetermined multiple unit pulse code inserted between an associated start and stop pulse of preselected widths comprising first switch means receiving said input teletype signals, said first switch means having two positions, and first being a cipher position and the second a text position, with said first switch means in said first position, a resistive attenuator interconnecting a first emitter follower transistor with said first switch means, said resistive attenuator also providing bias to said first emitter follower transistor, enciphering means having a single input and a first and second output, with said input being connected to the output of said first emitter follower transistor, said means mixing in a preselected random manner said predetermined multiple unit pulse code while retaining their associated start and stop pulse in their original position, a bistable multivibrator having first and second inputs and a single output, said first and second inputs being connected to said first and second outputs, respectively, of said enciphering means, a peaking circuit interconnecting said output of said bistable multivibrator with a second emitter follower transistor, and a common emitter connected transistor operating as a driver and receiving the output signal from said peaking circuit for delivery to an output terminal for further transmission.