Keying

About: Keying is a research topic. Over the lifetime, 6598 publications have been published within this topic receiving 82943 citations.

Probability of error of M-ary PSK and DPSK on a Rayleigh fading channel

Abstract: M-ary phase-shift keying and differential phase-shift keying (DPSK) on a slow fading Rayleigh channel without diversity is investigated. Expressions for the distribution of the phase angle between a vector with Rayleigh amplitude distribution and a noiseless reference, and between two vectors both with Rayleigh amplitude distribution perturbed by Gaussian noise are obtained. >

Spread spectrum communication system

Abstract: A spread spectrum communication system includes a transmitter and a receiver, and an on-off keying signal is inputted to the transmitter. A carrier signal is modulated by the on-off keying signal, and a spread spectrum signal is produced by multiplying a modulated signal by a first PN code (16) which is repetition of 3-bit data. The spread spectrum signal is transmitted through a transmission antenna (19). In the receiver, a second PN code which is repetition of 4-bit data larger than the first PN code by 1 bit is generated. Therefore, a phase of the second PN code becomes coincident with a phase of the first PN code every 12 bits. Then, a spread spectrum demodulation is performed by multiplying (24) a received spread spectrum signal by the second PN code to reproduce the carrier signal being modulated by the on-off keying signal. The on-off keying signal is restored by envelope -detecting a reproduced carrier signal.

Alphabetic Data Entry via the Touch-Tone Pad: A Comment

Abstract: Computer analysis indicates the feasibility of single-stroke keying for data entry of alphabetic names using the standard touch-tone telephone pad. In many practical job situations little ambiguity...

Laser linewidth requirements and improvements for coherent optical beam forming networks in satellites

Abstract: A coherent optical beam forming network using phase-locked semiconductor lasers as sources is presented. For this scheme the spectral purity of the intermediate frequency derived from mixing the signals from two semiconductor lasers is considered. The relationship between the linewidths of the lasers in a satellite transmitter and the phase error at the detector of a microwave differential quaternary phase-shift keying earth station receiver is analyzed. The demands placed on the linewidths from the point of view of phase stability requirements are calculated using quaternary phase-shift keying modulation at data rates of 33 and 131 Mb/s. It is shown that a substantial improvement in performance can be achieved when phase locking the two lasers to each other is feasible. >

On the Q factor inaccuracy in the performance analysis of optical direct-detection DPSK systems

Abstract: In this letter, we analyze the validity of the use of the Q parameter evaluation in the study of the bit-error-rate (BER) performance of direct-detection differential phase-shift keying optical systems. We show that the inaccuracy of the estimate of the BER based on the Q factor can be very large.