Abstract: Method and apparatus for encoding transmitted data and decoding the data at a receiving facility. The data is divided into elements of equal length. Each element is assigned an age number having a value within a prescribed range. The age value determines the number of delay intervals experienced by each element before being transmitted. Delays of the proper length are obtained by the use of storage elements. Age numbers are assigned arbitrarily. The age numbers are incremented upon the passage of each delay interval. Values within the aforementioned range are randomly generated. A data element is removed from storage and transmitted when: (1) its age number compares with the randomly generated value; or (2) when its age number reaches the extreme value; or (3) when its age number is zero. A new element is placed in storage simultaneously with the removal of an element therefrom.At the receiver end elements are stored and their age numbers are incremented upon the occurrence of each delay interval.

Abstract: Method and apparatus for demodulation of a phase shift keyed carrier in which a plurality of auxiliary signal frequency sources are provided and a substantially constant phase difference is maintained therebetween. Each auxiliary signal frequency is mixed with the modulated carrier and the mixer outputs are combined to form the product thereof to yield a control signal for regulating the auxiliary.The sum and differences of the mixer output may be formed prior to forming the product thereof.Input signals to the product forming circuit are amplitude limited to limit variation of the control signal r between -1 .ltoreq.r .ltoreq.+1.A filter may be employed to smooth the control voltage and may be incorporated with switching means to periodically interrupt the control signal to limit evaluation only during the established keying phase.

Abstract: A method for stabilizing the mean-frequency and modulation slope of a frequency controlled oscillator used for generating PSK signals is disclosed. A control signal representative of the phase deviation between the PKS signal and a reference signal representative of the base frequency of the carrier signal is generated. The control signal is directly utilized to stabilize the mean-frequency of the PSK signal generated by the frequency controlled oscillator. After the control signal is inverted as a function of a data signal whose information is to be carried by the PSK signal, it is utilized to stabilize the modulation slope of the PSK signal.

Abstract: The known process for transmitting two or more audio signals over a single transmission channel by eliminating alternate small segments from a first signal and filling the gaps with alternate small segments of a second signal and then filling in the gaps in the received signals with repeated segments, is found to be significantly improved with respect to comprehension or understandability, etc., if the audio signals are divided into a low frequency subband and one or more high frequency subbands and if the lowest frequency subband is transmitted substantially continuously while the higher frequency subbands are segmented and transmitted as before. Processes and apparatuses for splitting the audible signals into high and low frequency subbands and for treating the signals both on the sending and receiving sides to take advantage of the above discovery are disclosed.

Abstract: Method and apparatus for enhancing the secret (confidential) transmission of voice (speech) type signals. The voice signals are encoded at a transmitter facility. Filling signals are inserted into breaks and interruptions normally encountered between words and/or phrases. Such breaks and interruptions may be either partially or completely filled with the filling signals which preferably correspond as close as is practical to the characteristic of either coded or uncoded voice signals with regard to time variation and spectral energy distribution and the filling signals may be derived from voice signals of either the coded or uncoded type which are at least temporarily stored by the transmitter facility. The resultant signal having either shortened or completely eliminated breaks and interruptions is then encoded and transmitted to a remote location. Alternatively, the voice signals may be intially encoded before the insertion of filling signals into the breaks and/or interruptions.

Abstract: Method and apparatus are disclosed whereby messages are encoded by message element exchangers which utilize a delay device for transposing selected pairs of message elements so that the first element of the pair undergoes a delay 2T and the remaining message element of the pair experiences no delay. Message elements not treated in pairs undergo a delay T. The delay T is an integral multiple of the duration of a message element (said elements preferably being of equal length T.sub.0). Transmitted messages which have undergone selective transposition are decoded in a similar fashion, whereby the undelayed message element of a pair undergoes a delay 2T, the remaining element of the pair undergoes no delay and messages elements not treated in pairs undergo a delay T.Exchangers of dissimilar delay periods may be connected in cascade to enhance the number of possible delay displacements which message elements may undergo.