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Multilevel amplitude-shift-keying (MASK) and quadrature amplitude-shift-keying (QASK) as signaling techniques for multilevel digital communications systems, and the problem of providing symbol synchronization in the receivers of such systems are discussed. A technique is presented for extracting symbol sync from an MASK or QASK signal. The scheme is a generalization of the data transition tracking loop used in PSK systems. The performance of the loop was analyzed in terms of its mean-squared jitter and its effects on the data detection process in MASK and QASK systems.

Multilevel amplitude-shift-keying (MASK) and quadrature amplitude-shift-keying (QASK) as signaling techniques for multilevel digital communications systems, and the problem of providing symbol synchronization in the receivers of such systems are discussed. A technique is presented for extracting symbol sync from an MASK or QASK signal. The scheme is a generalization of the data transition tracking loop used in PSK systems. The performance of the loop was analyzed in terms of its mean-squared jitter and its effects on the data detection process in MASK and QASK systems.

Multilevel amplitude-shift-keying (MASK) and quadrature amplitude-shift-keying (QASK) as signaling techniques for multilevel digital communications systems, and the problem of providing symbol synchronization in the receivers of such systems are discussed. A technique is presented for extracting symbol sync from an MASK or QASK signal. The scheme is a generalization of the data transition tracking loop used in PSK systems. The performance of the loop was analyzed in terms of its mean-squared jitter and its effects on the data detection process in MASK and QASK systems.

Multilevel amplitude-shift-keying (MASK) and quadrature amplitude-shift-keying (QASK) as signaling techniques for multilevel digital communications systems, and the problem of providing symbol synchronization in the receivers of such systems are discussed. A technique is presented for extracting symbol sync from an MASK or QASK signal. The scheme is a generalization of the data transition tracking loop used in PSK systems. The performance of the loop was analyzed in terms of its mean-squared jitter and its effects on the data detection process in MASK and QASK systems.

A representation of nonstationary narrowband random processes in terms of nonstationary quadrature components is proposed in a form analogous to that used to represent wide sense stationary narrowband random processes. The represen­tation is then applied to a specific case in which the nonstationary narrowband random process is generated by the product of white noise and a deterministic periodic signal and then is processed by a narrowband filter. This representation is used in the modeling of a bi-level pulsed noise jammer which is assumed to be present in a communication channel. The effect of such a jammer on a direct sequence, binary phase shift keyed (DS-BPSK) spread spectrum communication receiver is evaluated and characterized in terms of the error rate performance of the receiver. Families of performance curves are plotted to demonstrate the effect of various parameters, namely signal-to-noise ratio, jammer power to signal power ratio, and processing gain, on the error rate of the complete spread spectrum receiver. The analysis carried out differentiates between two cases, namely fast jammers and slow jammers. However, the analytical tools developed make it possible to consider either one of the two cases without resorting to quasi-stationary arguments as has been done in the past.

The method of synthesis of Barker signals’ on generalized matrix of autocorrelation function has been used. The details of “inner” structure of Barker’s signals with N = 5;7;11;13, have been shown, which are used for the synthesis of Barker signals’ with components noquantized in duration. Binary phase manipulated signals with length of code N [8;11], the side peaks of which don’t exceed the one on module have been discovered. The signals with the length of code N = 15, which, under appropriate processing, on quadratic criterion exceed the non existing Barker’s signals with N = 15 have been found. 

Tones and binary information are transmitted as phase variations on a carrier wave of constant amplitude and frequency. The carrier and tones are applied to a balanced modulator for deriving an output signal including a pair of sidebands relative to the carrier. The carrier is phase modulated by a digital signal so that it is + or - 90 deg out of phase with the predetermined phase of the carrier. The carrier is combined in an algebraic summing device with the phase modulated signal and the balanced modulator output signal. The output of the algebraic summing device is hard limited to derive a constant amplitude and frequency signal having very narrow bandwidth requirements. At a receiver, the tones and binary data are detected with a phase locked loop having a voltage controlled oscillator driving a pair of orthogonal detection channels.

Available from National Technical Information Service, Springfield, Va

Available from National Technical Information Service, Springfield, Va

The method of synthesis of Barker signals’ on generalized matrix of autocorrelation function has been used. The details of “inner” structure of Barker’s signals with N = 5;7;11;13, have been shown, which are used for the synthesis of Barker signals’ with components noquantized in duration. Binary phase manipulated signals with length of code N [8;11], the side peaks of which don’t exceed the one on module have been discovered. The signals with the length of code N = 15, which, under appropriate processing, on quadratic criterion exceed the non existing Barker’s signals with N = 15 have been found

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A representation of nonstationary narrowband random processes in terms of nonstationary quadrature components is proposed in a form analogous to that used to represent wide sense stationary narrowband random processes. The representation is then applied t a specific case in which the nonstationary narrowband random process is generated by the product of white noise and a deterministic periodic signal and then is processed by a narrowband filter. This representation is used in the modeling of a bi-level pulsed noise jammer which is assumed to be present in a communication channel. The effect of such a jammer on a direct sequence, binary phase shift keyed (DS-BPSK) spread spectrum communication receiver is evaluated and characterized interns of the error rate performance of the receiver. Families of performance curves are plotted to demonstrate the effect of various parameters, namely signal-go-noise ratio, jammer power to signal power ratio, and processing gain, on the error rate of the complete spread spectrum receiver. The analysis carried out differentiates between two cases, namely fast jammers and slow jammers. However, the analytical tools developed make it possible to consider either one of the two cases without resorting to quasi-stationary arguments as has been done in the past. (Theses).

Bibliography: p. [483]-487