Abstract: A mobile communication system is provided which serves as an information infrastructure capable of providing intelligent information transmission and services. A mobile station on each vehicle traveling on a road includes first and second transceivers for carrying out radio communications with a third transceiver of a base station installed on a roadside. The first transceiver of a first mobile station is linked not only with the third transceiver of the base station through a first communication channel, but is also linked with the second transceiver of a second mobile station via a second communication channel. The first mobile station carries out information communications with the base station using the first communication channel, and at the same time with the second mobile station via the second communication channel.

Abstract: An ultrasonic imaging system is provided for forming an orthographic and a tomographic image of an object. The system comprises a receiving transducer array having a plurality of elements positioned at the lattice points of a parallelogram and a transmitting transducer array having a plurality of elements arranged in a straight line parallel to one side of the parallelogram at a period equivalent to the length of the side. A receiving beam former compensates for the delay time of the received signal for each element in the receiving transducer array and adds the compensated signals for all the elements. The receiving beam former comprises a quadrature demodulator which decomposes the output of a receiving transducer element into the inphase component and the quadrature component of a transmitting carrier signal.

Abstract: There is disclosed a visual scan converter which accepts digitalized video data in a polar coordinates system from a source such as a radar receiver, a sonar, or an ultrasonic imaging system, and converts the data format to make it suitable for presentation on a cathode ray tube in a standard television or other orthogonal raster at flicker free rates. The input data in a polar coordinates system is first stored in a digital memory, which is read with the orthogonal coordinates system. In reading said digital memory, an orthogonal address generated by a raster address generator is converted to a polar address, which is applier applied to said digital memory. An interpolation is performed for the outputs of the digital memory.

Abstract: The sum and difference signals of a pair of data channels are applied to a pair of roll-off filters, respectively. The outputs of said roll-off filters are modulated by a pair of carrier signals which have the phase difference (.pi./2) to each other. The modulated signals are added to each other in an adder and a single output signal is provided from the output of said adder. Said output signal and another output signal relating to another pair of data channels, and some pilot signals are applied to an adder, the output of which is transmitted to a receiving station in the form of a multi-channel multiplex data signal. At the receiving station, the received signal is demodulated with the inverse process of the above modulation steps and the demodulated data signals are applied to an automatic equalizer. The present invention described above provides high speed data transmission through a narrow-band-line which has only almost the Nyquist band width.