Abstract: A redundancy system for use in a communications satellite. Eight traveling wave tube amplifiers are provided for five communications channels in a manner such that full service is maintained even though any three of the amplifiers have failed. A ten-switch network connects the five channels to the inputs of the eight TWT amplifiers, and a mirror-image ten-switch network connects the outputs of the eight TWT amplifiers to the five channels.

Abstract: A switch matrix for connecting any one of a large number of communications lines, transmitting a message header, with any other non-busy one of the lines. A plurality of connection links are provided. A message header identifies a transmitting line carrying a request-to-send signal, and the address of a desired receiving line. Means responsive to a received header determines the availability of an unconnected link and the not-busy condition of the desired receiving line, and connects a selected link from the transmitting line to the desired receiving line, whereby to permit the transfer of information. A link-activity checker operates automatically to disconnect a link when transmission of data through the link ceases.

Abstract: A digital phase synchronization system in which a received pulse wave is compared in a phase detector with a local pulse wave obtained by frequency dividing the output of a local oscillator. One output of the phase detector is used to control the subtraction or addition of pulses from the local oscillator until phase synchronization is achieved. Another output of the phase detector is used to control the number of pulses which are subtracted or added. The number of pulses subtracted or added is proportional to the phase difference when the phase difference is greater than a predetermined value, and is limited to one or a few pulses when the phase difference is below the predetermined value.

Abstract: An engine diagnostic apparatus includes a first transducer positioned in the oil filler neck of the engine for translating the crankcase pressure waveform into a corresponding electrical waveform having a frequency component proportional to engine speed. A second transducer is positioned to translate an exhaust pressure waveform emitted by the engine to a corresponding electrical waveform having a frequency component representative of an engine fault at a frequency proportional to engine speed. The two frequency components are compared to provide diagnostic information.

Abstract: A flat field laser recorder includes means to direct a beam from a laser through an acousto-optic light modulator, an acousto-optic light deflector/modulator, and a beam scanner, to scan-lines on a linearly-moving light-sensitive film. The acousto-optic light modulator is operated by electrical oscillations which are amplitude modulated by a video information signal. The acousto-optic light deflector/modulator is operated by electrical oscillations which are amplitude modulated to provide an automatic brightness control of the beam, and are frequency modulated to provide an automatic scan-line spacing control. In addition, a plurality of simultaneous oscillation frequencies are selectively applied to the deflector/modulator to provide beam spot elongation control in the direction perpendicular to the scan-lines.

Abstract: A phase locked loop including a voltage-controlled oscillator and a divider is used to derive a clock timing signal from a received data stream having a given bit transmission rate. The divider may be programmable so that the circuit can derive a clock from a data stream having any one of a plurality of integrally-related bit rates. A second phase locked loop (having a second programmable divider) is inserted in the feedback path to permit clock recovery from data streams having fractionally-related bit rates.

Abstract: In a system in which alternate lines of one color television video signal normally are delayed half the period of the color subcarrier at a transmitting terminal to minimize the cross modulation of the color subcarrier with the color subcarrier of another video signal amplified in a common amplifier such as in a satellite transponder, an intermediate line delay unit at the receiving terminal is normally operative to delay intermediate lines of the one video signal half the period of the color subcarrier, and is automatically inhibited from delaying intermediate lines of the one video signal when the received alternate lines of said one video signal are for any reasons not delayed at the transmitting terminal.

Abstract: A recording and reproducing system capable of recording at one speed and playback at another speed includes a capstan linear drive for a tape, and a headwheel drive means to drive heads in a transverse direction over the tape. Recording and/or playback is accomplished at any speed within a first given two-to-one speed range by operating the capstan linear drive at a corresponding speed, and by operating the headwheel at a speed which has a first given constant ratio with the linear speed. Recording and/or playback is accomplished over a second different adjacent two-to-one speed range by operating with the capstan linear drive at a corresponding proportional speed, with the headwheel at a speed which has a second different constant ratio with the linear speed, and with the rotating headwheel physically tilted by a given small angle relative to the transverse direction.

Abstract: A circuit for generating a clean square electrical pulse having a duration equal to the spark zone duration in an internal combustion engine includes a comparator connected to produce an output when the signal input thereto, coupled from the primary winding of the ignition coil, exceeds a predetermined high voltage at the reference voltage input of the comparator. A one-shot multivibrator triggered by the initial output of the comparator generates an output continuing beyond the duration of high voltage ringing in the signal from the ignition coil. A "nor" gate receptive to outputs from the comparator and the one-shot produces an output which reduces the reference voltage applied to the comparator to a value below the plateau of the signal from the ignition coil. The "nor" gate provides the desired output spark zone duration pulse.

Abstract: A phase locked loop includes a voltage-controlled oscillator, and a phase and frequency detector for comprising an input signal pulse wave with a pulse wave from the voltage-controlled oscillator, and for providing a frequency control voltage to the voltage-controlled oscillator. When the pulses overlap, a pulse comparison circuit in the phase and frequency detector produces a frequency "up" signal or a frequency "down" signal proportional to the correction necessary. When the pulses do not overlap, the pulse comparison circuit produces a "non-overlap" signal which effects a rapid frequency correction by causing a current pump in the phase and frequency detector to increase its output to a fixed maximum value, and by causing a loop filter to increase its bandwidth to a fixed maximum value.

Abstract: Couplers for coupling achromatic light having wavelengths of blue through red to and from an optical film waveguide along collinear paths parallel with the waveguide. Each coupler is constituted by a prism made of a material which, over the range of wavelengths of interest, has a change in refractive index which differs from the change in refractive index of the waveguide film by less than 0.5 percent of the refractive index of the prism material.

Abstract: An analog-to-digital (A/D) converter which is capable of encoding each one of analog signal samples occurring at a high rate, such as 40 MHz (25 ns spacing), to eight digital output bits representing any one of 256 levels. Sixteen sixteen-level A/D converter sub-units each providing four binary output bits are connected in series across analog signal input terminals. A priority encoder and a multiplexer are responsive to the carry outputs of the A/D sub-units to produce four high-order digital output bits representing the rank of the sub-unit having a voltage range encompassing the voltage of an analog input signal. Gating means responsive to the four high-order output bits pass four low-order digital output bits from the one of the sixteen sub-units identified by the four high-order bits.

Abstract: A plastic sheet is embossed with three angularly-multiplexed holograms to represent three colors of an image. Light is directed to the holograms from three directions, in sequence, to recreate the three colors of the image in sequence on the face of a black-and-white vidicon. The three field sequential signals from the vidicon are sequentially stored in three solid state frame memories, from which the three color-representing signals are read out simultaneously to the three guns of a color kinescope. Alternatively, the three holograms represent red, blue and luminance, and only red and blue frame memories are required, and during display the luminance-representing signal is repeatedly read out from the vidicon to the color kinescope simultaneously with repeated readout from the red and blue frame memories.

Abstract: Data relating to the attitude and spin rate of a spacecraft is stored in a data storage system located at an earth station in communication with the spacecraft. Leading and trailing edges of the data, usually in the form of pulses, received from sensors suitably mounted on the spacecraft, address locations in a random access memory (RAM) into which the count accumulated in a counter is written. At the end of each group of pulses, referred to as a frame, data relating to the status of the pulses received from the spacecraft is also loaded into the random access memory. Simultaneously, a computer is signalled that a complete frame of data has been loaded in the random access memory. The computer then generates address and other signals such that the data can be read out of memory and thereby allow the computer to calculate the attitude and spin rate of the spacecraft.

Abstract: An interface unit for use between a telephone system in which a single-frequency tone is transmitted in both directions when the circuit is on-hook (idle) and a single-channel-per-carrier radio system in which the radio frequency carrier is not transmitted when the circuit is idle. A transmitting portion includes a single-frequency tone detector means responsive to termination or initiation of the tone from the telephone system to turn on the radio frequency carrier. A receiving portion includes a radio frequency carrier detector means operative to switch the telephone system from the output of a local single frequency local oscillator to a voice frequency line from the radio system, and a single frequency detection means to switch the telephone system back to the output of the local single frequency oscillator.

Abstract: Buffer division matrix for multiplexing and demultiplexing information signals in a communication system. A controller network controls information flow through a memory shared with a processor. The shared memory and the controller network comprise the buffer matrix, operating as a buffer division circuit switch and as a dynamic multiplexer/demultiplexer for high speed trunks. The buffer matrix is coupled to the processor as if the matrix were a memory. A control memory contains information about each subscriber and trunk to be serviced by the buffer matrix, information to control channel scan, and the characteristics of each channel. The control memory is initialized by the processor. Subscanning is implemented to increase the efficiency of the system.

Abstract: The cylinder of an internal combustion engine having a fault is identified by using a non-contacting transducer to generate a reference engine-cycle electrical signal having a phase determined by a reference one of the cylinders of the engine, and by using a non-contacting transducer to generate a fault engine-cycle electrical signal having a phase determined by the one of the cylinders having a fault. The phase difference between the fault electrical signal and the reference electrical signal is translated to a number identifying the cylinder having the fault.

Abstract: A desired output frequency can be generated by applying a corresponding digital phase step number to an accumulator to generate multiples of the number for application to a sine wave look-up table from which digital samples of the sine wave amplitude are obtained. The digital samples can be applied through a digital-to-analog converter to produce the desired output frequency in analog form. A time division multiplex system is disclosed in which a plurality of digital phase step numbers are used to generate an equal plurality of output frequencies. Each digital phase shift number may be altered in accordance with modulating signals so that each output frequency is frequency-shift keyed, and/or phase shift keyed, and/or on-off keyed.

Abstract: The compression in the cylinders of an internal combustion engine is tested by analyzing the battery voltage waveform when the engine is cranked by the starter motor with ignition or fuel inhibited. The detected voltage waveform is amplified in a manner to emphasize the a-c component having cycles between positive voltage peaks, each cycle having a negative voltage peak due to a compression stroke. A missing negative voltage peak indicates a very low compression in one cylinder. The voltage cycles are integrated and the integrals are compared to detect compression imbalance. The base level of each integration is made equal to the level of an adjacent positive voltage peak.

Abstract: A pulse code modulation (PCM) time division multiplex (TDM) telephone exchange to which n telephone lines are sequentially connected during n respective sequential time slots. An unlimited number of phones may be connected together for conference purposes by means of a summation memory in which each conference storage location is used for accumulating the sum of message samples from one or more lines during a write-in cycle and supplying the sum of the message samples to one or more of the lines during a subsequent read-out cycle. The summation memory is indirectly addressed by a connection control memory. A portion of each message sample stored in a sample memory is subtracted from each sum of message samples read out during the same time slot from the summation memory, so that a speaker hears an attenuated sidetone version of his own voice.