GB401564A - Method for the arbitrary distortion and correction of wireless or wire transmitted alternating currents, such as speech and signal alternating currents, by means of superimposed disturbance alternating currents - Google Patents

Abstract

401,564. Secret telephony &c. K€SEMANN, E., 15, Bernhard Beyerstrasse, Steinst³cken, near Berlin. March 13, 1933, No. 7543. Convention date, Jan. 20, 1933. Drawings to Specification. [Class 40 (iv).] A method of secret transmission of telephony, television &c. consists in superposing on the signals, before transmission, distorting signals from a phonograph record, and counterdistorting at the receiving end with signals from a similar record in counterphase with the distorting signals. The received signals may be recorded and counter-distorted during reproduction, and the transmission may include a wireless link. Synchronization may be effected by the transmission of impulses recorded on the said record or on an auxiliary record. The records may be photographic, magnetic or ordinary disc records, an iron disc with an irregular periphery moving between the poles of an electromagnetic pick-up and a glass disc with a photographic recording are particularly described. The distorting currents may be amplified before superposition, and the amplitude of the counter-distorting currents is adjusted to prevent over-correction, line distortion being compensated by equalizers. The distorting currents may be derived from two or more records or by picking up from two or more points of one record and secrecy may be further ensured by changing, continuously if desired, the position of the pick-ups, these changes taking place according to a plan known at the receiving station. Where two records are used, the phase relationship between the correcting currents may be adjusted by temporary variation in speed of one record.