Abstract: A static random access memory device is usually equipped with an address decoder having unused output nodes, and an external address signal designating one of the unused output nodes causes output data paths to be kept in a precharged state and, accordingly, feed-through current to flow through output data drivers, because only small differential voltage is left between the precharging voltage level and the threshold level of the component transistors of the output data drivers, wherein a switching circuit allows the output data paths to couple with either high or low voltage source upon selection of one of the unused output nodes so as to protect the output data paths against the feed-through current.

Abstract: The present invention provides two branches of a base station transmitter and a base station receiver, respectively, and inserts a delay circuit for ensuring a delay time difference between D and U waves required to obtain the best bit error rate for a DSK system, BPSK-RZ system, QPSK-RZ system or the like, into each system of the transmitter and the receiver, respectively, or into either the transmitter or the receiver of each system, thereby efficiently improving the bit error rate.

Abstract: A digital communication system, in which digital information is represented by a quaternary information symbol (11, 01, 00, 10) and the double step phase shift, each step represented by (.pi./4, 3.pi./4, 5.pi./4, 7.pi./4), is performed per 1/2 time slot in correspondence to each information symbol, so that the number of phase shift per unit time in the case of the identical transmission rate can be decreased to 1/2, as compared with a .DELTA..theta./2-DSK system, and expansion of the bandwidth can be decreased to 1/2.

Abstract: The present invention provides a digital communication system in which one time slot is divided into a first half section and a second half section and the carrier phase difference .theta. between each neighboring first half section is set to either (.pi., 0) with respect to a binary information symbol (1,0) or (0, .pi./2, .pi., 3/2.pi.) with respect to a quaternary information symbol (11, 01, 00, 10). In addition, the phase difference .psi. between the first half and the second half of any time slot is a constant value .psi..sub.0 (for example, .pi.rad) irrespective of the symbol, or .psi..sub.i determined with respect to a symbol (for example, +.pi./2 with respect to a symbol 1 or -.pi./2 with respect to a symbol 0). Therefore, an arbitrary complementary characteristic can be obtained when differentially demodulated in a multipath fading channel, irrespective of the amplitude characteristic of a demodulation signal.

Abstract: The present invention provides a communication system which employs a signal whose carrier phase is shifted by a constant amount .DELTA..theta. per time slot in correspondence to each symbol (1 or 0) transmitted, and the phase shift is performed by .DELTA..theta./2 (or -.DELTA..theta./2) in the first 1/2 time slot and further by .DELTA..theta./2 (or -.DELTA..theta./2) in the second 1/2 time slot thereby to improve the bit error rate in multipath propagation.