Abstract: Centralized controlling apparatus controls overall flow of signals. Calling apparatus transmits a call signal in response to a call instruction signal transmitted from the centralized controlling apparatus. Information receiving apparatus receives the call signal to transmit an answer signal. Answer receiving apparatus transmits an answer acknowledge signal when it receives the answer signal. The centralized controlling apparatus transmits an information/control signal to information transmitting/distributing apparatus when it receives the answer acknowledge signal. The information transmitting/distributing apparatus distributes the information/control signals to a plurality of information transmitting apparatus. The plurality of information transmitting apparatus transmits simultaneously the information signals to the information receiving apparatus by radio.

Abstract: A diversity system utilizing a plurality of branches has been found for an angle modulated digital signal transmission. The received signal on each branch is modulated with a local signal which has the same period as the digital signal, and satisfies the orthogonal relationship with each other. The modulated signals are combined by simply summing them, and the combined signal is differentially detected. In the case of two branches, said orthogonal local signals are .sqroot.2/T.multidot. sin (2.pi./T)t, and .sqroot.2/T.multidot. cos (2.pi./T)t, where T is the bit duration of the digital signal, and said local modulation is the amplitude modulation. The present invention can provide the same diversity effect as the prior maximal ratio combining system, although the present invention does not utilize a complicated cophasing means between each branches.

Abstract: In a multitransmitter digital signaling system for mobile communications consisting of a plurality of base stations, different waves are superposed on the digital information signals in adjacent base stations and carrier waves of the same frequency are angularly modulated by the superposed signals at the same modulation index and simultaneously transmitted from the base stations to one service area.

Abstract: The differential detection system comprises a demodulator for a modulated carrier transmission system for binary signals, in which a symbol detected from the phase difference between the received signal delayed by one signaling interval and the signal received in the present signaling interval is converted into data and a symbol detected from the phase difference between the received signal delayed by two signaling intervals and a signal received in the present signaling interval is converted into parity. The data and the parity are applied to a decoder for a rate 1/2 single error correcting self-orthogonal convolutional code effecting demodulation with non-redundant error correction. The correction system is also applicable to demodulate a carrier wave modulated by m (an integer) level digital data.

Abstract: A unique carrier frequency allocation in a digital mobile communication system having a service area consisting of a number of radio coverage zones is disclosed. A single standard carrier frequency is used in the service area but the carrier frequencies are arranged to be slightly shifted relative to each other for stations in adjacent radio coverage zones in order to improve the receiving efficiency in a region covered by overlapping zones. The invention defines a condition for the shift frequencies for the radio coverage zones.