Abstract: The specification discloses a digital cryptographic system wherein each of the transmitting and receiving units includes a housing having a front panel. A push-button switch input array is mounted on the front panel, with each push-button switch corresponding to a different number to enable the manual inputting of code variables therethrough. A digital display is provided on the front panel to temporarily display each of the code variables input through the array. Storage circuits are provided to store the code variables input through the array. A switch is provided on the front panel to enable any one of the stored code variables to be selected. A random code generator is operable in response to the selected stored code variables in order to generate a sequence of randomized key digital bits. Circuitry is provided to encipher clear text digital data in a synchronous manner and to transmit enciphered data through a synchronous data link.

Abstract: The specification discloses an electronic digital enciphering system which is selectively operable in a plurality of different modes. The system may be operated in an off-line mode for preparing enciphered message tapes prior to transmission via teleprinter message circuits. The system may also be operated in an on-line asynchronous mode wherein a sending station may asynchronously transmit enciphered data on-line to a remote receiving unit, synchronization being provided by the start/stop pulses of the individual digital characters. The system may also be operated in an on-line synchronous mode wherein a sending and a receiving unit are automatically synchronized in time by local self-contained clocks in order to bridge fades or interference in a transmission medium such as radio telegraph, or the like. The system may be utilized on either half-duplex or full-duplex communication channels.

Abstract: The specification discloses an electronic digital enciphering system which is selectively operable in a plurality of different modes. The system may be operated in an off-line mode for preparing enciphered message tapes prior to transmission via teleprinter message circuits. The system may also be operated in an on-line asynchronous mode wherein a sending station may asynchronously transmit enciphered data on-line to a remote receiving unit, synchronization being provided by the start/stop pulses of the individual digital characters. The system may also be operated in an on-line synchronous mode wherein a sending and a receiving unit are automatically synchronized in time by local self-contained clocks in order to bridge fades or interference in a transmission medium such as radio telegraph, or the like. The system may be utilized on either half-duplex or full-duplex communication channels.

Abstract: The specification discloses an electronic digital enciphering system which is selectively operable in a plurality of different modes. The system may be operated in an off-line mode for preparing enciphered message tapes prior to transmission via teleprinter message circuits. The system may also be operated in an on-line asynchronous mode wherein a sending station may asynchronously transmit enciphered data on-line to a remote receiving unit, synchronization being provided by the start/stop pulses of the individual digital characters. The system may also be operated in an on-line synchronous mode wherein a sending and a receiving unit are automatically synchronized in time by local self-contained clocks in order to bridge fades or interference in a transmission medium such as radio telegraph, or the like. The system may be utilized on either half-duplex or full-duplex communication channels.

Abstract: The specification discloses a digital cryptographic system wherein each of the transmitting and receiving units includes a housing having a front panel. A push-button switch input array is mounted on the front panel, with each push-button switch corresponding to a different number to enable the manual inputting of code variables therethrough. A digital display is provided on the front panel to temporarily display each of the code variables input through the array. Storage circuits are provided to store the code variables input through the array. A switch is provided on the front panel to enable any one of the stored code variables to be selected. A random code generator is operable in response to the selected stored code variables in order to generate a sequence of randomized key digital bits. Circuitry is provided to encipher clear text digital data in a synchronous manner and to transmit enciphered data through a synchronous data link.

Abstract: The specification discloses circuitry useful in a digital cryptographic system having a digital prime sequence which controls the generation of randomized key data. The circuitry includes a register for storing the digital prime sequence prior to generation of the randomized key data. A memory is provided which includes address inputs and data outputs and which stores predetermined digital relationships. A stage of the register is connected to an address input of the memory to select one of the stored digital relationships. A source of selectable digital bits is connected to another address input of the memory. The data outputs of the memory are operable to be coupled to the input of the register for generating an enciphered digital prime sequence. A clock clocks the contents of the register through the stages of the register in order to cause the enciphered digital prime sequence to be loaded into the register.

Abstract: The specification discloses a random digital code generator operable over a series of key cycles for generating a randomized digital bit during each key cycle. The generator includes a plurality of first registers each having a predetermined cycle period which does not have a common factor with the cycle period of any other of the first registers. Circuitry is provided to step each of the first registers a predetermined number of steps per key cycle. A plurality of second registers are provided, along with circuitry for generating different numbers of clocking signals per key cycle for each of the second registers. Circuitry generates control pulses in response to the clocking signals and further in response to digital bits derived from selected taps on the first registers. The control pulses randomly control the number of times each of the second registers is stepped during each key cycle.

Abstract: The specification discloses an electronic digital enciphering system which is selectively operable in a plurality of different modes. The system may be operated in an off-line mode for preparing enciphered message tapes prior to transmission via teleprinter message circuits. The system may also be operated in an on-line asynchronous mode wherein a sending station may asynchronously transmit enciphered data on-line to a remote receiving unit, synchronization being provided by the start/stop pulses of the individual digital characters. The system may also be operated in an on-line synchronous mode wherein a sending and a receiving unit are automatically synchronized in time by local self-contained clocks in order to bridge fades or interference in a transmission medium such as radio telegraph, or the like. The system may be utilized on either half-duplex or full-duplex communication channels.

Abstract: The specification discloses a voice scrambler technique wherein a voice signal is split into a plurality of discrete frequency sub-bands. A random code generator generates a randomized sequence of digital signals. A preselected first portion of each of the digital signals is utilized to control the rearrangement of the order of the frequency sub-bands according to a limited subset of all possible combinations of rearrangements of the frequency sub-bands. The limited subset is chosen to include only the most unintelligible of the possible combinations of rearrangements of the frequency sub-bands. A preselected second portion of each of the digital signals is utilized to control the random inversion of one of the frequency sub-bands.

Abstract: The specification discloses a voice scrambler technique wherein a voice signal is split into a plurality of discrete frequency sub-bands. A random code generator generates a randomized sequence of digital signals. A preselected first portion of each of the digital signals is utilized to control the rearrangement of the order of the frequency sub-bands according to a limited subset of all possible combinations of rearrangements of the frequency sub-bands. The limited subset is chosen to include only the most unintelligible of the possible combinations of rearrangements of the frequency sub-bands. A preselected second portion of each of the digital signals is utilized to control the random inversion of ones of the frequency sub-bands.

Abstract: The specification discloses a voice scrambler technique wherein a voice signal is split into a plurality of discrete frequency sub-bands. A random code genertor generates a randomized sequence of digital signals. A preselected first portion of each of the digital signals is utiized to control the rearrangement of the order of the frequency sub-bands according to a limited subset of all possible combinations of rearrangements of the frequency sub-bands. The limited subset is chosen to include only the most unintelligible of the possible combinations of rearrangements of the frequency sub-bands. A preselected second portion of each of the digital signals is utilized to control the random inversion of ones of the frequency sub-bands.

Abstract: A hydrodynamically balanced quiet control valve for a submarine (underwater ehicle) hovering system. The valve has a cylindrical valve element within a four-port valve housing. The interior of the valve element is divided into three chambers by a pair of parallel partitions extending lengthwise of the element and equally spaced from the element axis. Apertures in the cylindrical wall of the element are arranged, in cooperation with the partitions, to produce substantially constant total flow resistance through the valve when installed in the system, regardless of the angular rotation of the cylindrical valve element. A hover computer controls the angular position of the element in response to sensed pressure variations from the pressure at a preselected hovering depth.