Sanders Associates Limited

Lockheed Martin Corporation

Alfred J Cann

Martin R Richmond

Royden C Sanders

Bruce A Ricker

Suppression of jamming from multiple sources is achieved by detecting the AM difference frequency produced by the beating of a desired signal and the smaller of the multiple jamming signal with the stronger jamming signal and applying same to one input of a single-sideband modulator while simultaneously applying the received signal (containing both the desired signal and the jamming signals) to the other input to the single-sideband modulator whereby the larger jamming signal is suppressed. The sum and difference outputs of the single-sideband modulator containing the upper and lower sidebands, respectively, of the desired signal plus the smaller jamming signal are each processed by a jamming cancellation circuit to suppress the smaller jamming signal and their outputs combined to receive the desired signal.

Multiple source jamming signal cancellation system

A low-loss, low-cost passive pulse width to voltage converter is provided by utilizing a diode clamp having a resistor in series therewith to provide a soft clamp or integrating clamp.

Pulse width to voltage converter circuit

A new method and apparatus for generating an analog output signal as a function of a digital input in the form of digital words over a specified range. The range is divided into a plurality of intervals, and the function is approximated by a linear segment in each interval. Each linear segment is defined by a step value, which is the value of the linear segment at the beginning the interval, and a slope value, which is the slope of the linear segment in the interval. The function is then approximated for any desired digital word in the range by determining the step and slope values for the interval into which the digital input signal falls, determining an incremental value by multiplying the slope value by the difference between the digital input signal and the value of the digital input signal at the beginning of the interval, and adding the incremental value to the step value.

Digitally controlled electronic function generator

Attenuation of a signal is achieved by biphase modulating the signal with an asymmetrical duty factor rectangular wave. In one embodiment of the invention an input signal is applied to a phase reversal switch having as its second input thereto an asymmetrical duty factor rectangular wave.

Attenuator

A satellite relay communications system includes a ground relay station arranged so that each message from one subscriber to another is relayed by the satellite relay to the ground relay, processed by the ground relay and then transmitted to the second subscriber by way of the satellite relay. Processing at the ground relay station includes a switching function in which the carrier frequency of each message is changed from the frequency used for transmitting by the subscriber sending each message to the frequency used for reception by the subscriber to whom the message is addressed. This permits each subscriber to use a single transmitting frequency and a minimum number of receiving frequencies.

Satellite communications system incorporating ground relay station

Reduction of interference from off-frequency signals in an a.m. receiver is achieved by substituting an average detector for the conventional peak detector employed in such receivers. Conversely, enhancement of off-frequency signal reception is achieved by employing an average detector in parallel with a peak detector with their outputs subtracted.

Modified A. M. detector

A single configuration-invariant hybrid phasing circuit is utilized for both phase detection and phase shifting in a quasi-coherent memory to produce an essentially constant amplitude CW signal which is later gated to produce constant amplitude false range pulses. In one mode of operation the subject circuit acts as a phase detector to sense the phase difference between a portion of the received signal and the recirculated signal. In the other mode of operation the subject circuit acts as a phase shifter to phase shift the recirculated signal such that this phase difference is less than 45.degree.. This effectively adjusts the loop delay for the wavelength of the incoming signal. Thus, the subject circuit adjusts the phase of the signals in a recirculation loop of the quasi-coherent memory such that no portion of the CW signal formed during the recirculation is out of phase with any other portion by more than 45.degree., to thereby limit amplitude variations in the transmitted pulse level with frequency.

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Wilton, NH, United States of America

Alfred J Cann