Raytheon Company

Nathan A Liskov

Robert G Curtis

William J Bickford

Paul J Tanzi

Caesar J Favaloro

David L Hendry

Gregory L Pence

An eye opening monitor for a binary waveform such as provided as the video output of a demodulator. At the decision sample time, the video is compared to -V.sub.th and +V.sub.th reference voltages to determine if it falls in the range defined therebetween. If it does, a counter is reset. Because the carry-out pulses of the counter are used to produce -V.sub.th and +V.sub.th, the range defined therebetween is decreased by the additional time required to count to the carry-out after the counter is reset. The loop stabilizes with the range from -V.sub.th and +V.sub.th being quantitatively indicative of the eye opening. A voltage derived from V.sub.th is visually displayed.

Eye opening monitor

A multiplexer system providing a transmission frame field containing information derived from the cumulative total of stuff bits used over a plurality of frames. The stuff bits which also have assigned positions in the transmission frame are generally used in asynchronous systems to compensate for the input data rate of a group not being a fixed submultiple of the transmission rate. The demultiplexer system uses the information derived from the cumulative total to improve the bit count integrity performance of data channeled out to a user device. Also, during transmission fade conditions, the demultiplexer uses information derived from the frequency of past stuff operations to maintain group bit count close to its expected value.

Multiplexer system providing improved bit count integrity

A digital data communication system employing quaternary phase-shift keying for transmission by a microwave radio link. The digital modulation of the quadrature channel is delayed from the in-phase channel by one-half the time duration of a bit so that the transmitted phase does not experience a quantum shift in excess of 90.degree.. This permits the use of an injection locked oscillator as an amplifier of the microwave transmission.

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Waltham, MA, United States of America

Nathan A Liskov