Abstract: An apparatus for providing electronically tunable biphase modulation. The apparatus includes an input for supplying a signal to be modulated and a coupler including first, second, third and fourth ports. The first port is coupled to the input. The apparatus also includes a first switch coupled to the second port. The first switch operates in response to a modulating signal. The apparatus further includes a first reactance element coupled to the first switch, an output coupled to the third port, a phase-shifting network coupled to the fourth port, a second switch coupled to the phase-shifting network and a second reactance element coupled to the second switch. The second switch operates in response to a modulating signal.

Abstract: An apparatus for providing electronically tunable biphase modulation including an input and a first switch having a first output, a second output and a first input coupled to the input. The first switch couples the first input to either the first output or to the second output in response to a modulating signal. The apparatus also includes a first signal path having a first phase shift and a second signal path having a second phase shift different than the first phase shift. The first signal path is coupled to the first output and the second signal path is coupled to the second output. The apparatus also includes a second switch having a first input coupled to the first signal path, a second input coupled to the second signal path and a terminal output.

Abstract: A microprocessor based system which implements BCH decoder algorithms in a sufficiently efficient manner to allow real time BCH decoding of a BCH(255,131) code is disclosed. Table lookup operations utilizing successive M-bit serial portions of BCH encoded input data as table offsets permit the microprocessor to generate syndrome using M-bit parallel portions of the input data. Additional table lookup operations which utilize tables stored in ROM memory speed execution time of multiply operations and detection of roots for inverse error location polynomials.