Communications Satellite Corporation

William H Childs

Christoph E Mahle

Peter A Carlton

An MSK modulator having a simple construction with only a single necessary adjustment. The digital bit stream to be modulated is fed directly to the control input of a 0,.pi. phase shifter in a single-sideband modulator. A phase shift circuit is used to couple an IF signal to the IF signal input of the single-sideband modulator with the phase thereof adjusted by 0 or .pi. in response to two contiguous bits of the input data stream so as to maintain phase continuity in the output of the modulator for all possible bit combinations in the input stream.

Simplified minimum shift keying modulator

A temperature compensated time delay element employs a non-temperature compensated delay element along a first delayed path, and a second non-temperature compensated delay element along a second 'undelayed' path to provide a net time delay equal to the difference between the delays in the delayed and undelayed paths. The substrate materials used in the delay elements in the delayed and undelayed paths, and the time delays of the two paths, are selected such that the variation of net phase shift, or time delay, with temperature is zero. The temperature coefficients of the substrate materials in the delayed and undelayed paths can both be positive, thus allowing the use of common substrate materials. The temperature compensated time delay element finds particular utility in differentially coherent signal detection systems.

Temperature compensated time delay element for a differentially coherent

A microwave integrated circuit (MIC) quadrature phase shift keying (QPSK) modulator uses a novel arrangement of couplers to permit the IF ports to be adjacent one another so that, in mixer applications, it is unnecessary for the circuitry to leave the plane of the MIC. A symmetrical arrangement of the MIC ensures near-perfect phase orthogonality of the RF.sub.2 split and the power/phase identity of the RF.sub.1 split.

Planar QPSK demodulator

A microwave integrated circuit (MIC) quadrature phase shift keying (QPSK) demodulator uses a novel arrangement of couplers to permit the IF ports to be adjacent one another so that, in mixer applications, it is unnecessary for the circuitry to leave the plane of the MIC. A symmetrical arrangement of the MIC ensures near-perfect phase orthogonality of the RF.sub.2 split and the power/phase identity of the RF.sub.1 split.

Periodic fins are provided on the lid of a microwave integrated circuit (MIC) package in order to reactively suppress specified bands of frequency and thereby increase the permissible dimensions of the MIC package.

Periodic lid for integrated circuit

A planar microwave switch matrix is composed of three-state phase shifter switches, a planar crossover and switchable 3-dB attenuators. The three-state phase shifter switches are each composed of two planar 3-dB quadrature hybrid couplers interconnected by two switchable phase shifters. The phase shifters are both switchable between zero phase delay and a predetermined phase delay, but the predetermined phase delay is different for each phase shifter. The planar crossover is composed of two cascaded 3-dB quadrature hybrid couplers. The construction of all components of the switch matrix is readily implemented using microwave integrated circuit (MIC) technology. The switch matrix is intended for use in switched satellite time division multiple access (SS-TDMA) systems but can be remotely configured for broadcast applications.

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Gaithersburg, MD, United States of America

William H Childs