| 4011408 |
Audio transmission protection apparatus |
| Mar-8-1977 |
In delay module means, an input signal is divided into a number of subsignals, each separated from the others by a selected time delay. In a primary module the subsignals are selectively weighted and combined... |
| 4004089 |
Programmable cryptic device for enciphering and deciphering data |
| Jan-18-1977 |
An encrypter for encoding and decoding data, wherein clear text data to be encoded is logically combined with a portion of a non-linear pseudo-random bit sequence signal to provide a partially encoded... |
| 3985958 |
Secret telephony |
| Oct-12-1976 |
1. In secret telephony, means to analyze speech message waves into slowly varying currents representative of energy variations in respective portions of the speech frequency band, distributor means for... |
| 3978288 |
Method and apparatus for the secret transmission of speech signals |
| Aug-31-1976 |
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... |
| 3970790 |
Method and device for the coded transmission of messages |
| Jul-20-1976 |
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... |
