A new switching diversity technique employing a carrier-jitter sensor is proposed for application to mobile radio transmission systems. Performance of the sensor has been examined both theoretically and experimentally, and it is found to respond well to noise as well as interference. In addition, this sensor can be implemented by digital devices. Diversity experiments in which a digital-type sensor was employed in digital mobile radio channels show that diversity effectively reduces performance degradation due to multipath fading.

Polarization evolution and the degree of polarization in twisted optical fiber are measured using an identical fiber sample. Measured polarization degree is consistently explained using independently measured linear birefringence, polarization dispersion and light source spectral data. As the result, polarization characteristics in twisted optical fibers could be comprehensively understood by revealing the mutual relation between several characteristics. Twisted optical fiber is designed based on equations supported by experiment. To get good polarization preserving fiber with a twist rate as low as several turns/m, core ellipticity of starting fiber should be less than about 1%. Linear birefringence and polarization dispersion data are compared with theoretical values derived from fiber parameters and the sources of discrepancies are discussed.

This paper proposes a new residue number multiplication scheme based on the cylic type of relationship which exists between the entries in the residue number multiplication truth-table when the modulus is any prime number. Using the scheme, multiplication is direct without table consultation and an entire truth-table is realizable. The multiplier circuit is simple and compact and allows pipelined processing of data. The flexibility of the multiplier is exploited in the implementation of an RNS based high-order FIR digital filter by using a programmable low order section. The suitability of the modular digital processor for VLSI is also indicated.

This paper describes the voice-data hybrid transmission facilities, which can be obtained by using 64 kbit/sec digital line. Instead of using separate transmission facilities for voice and data services, or instead of increasing the digital transmission rate, the silent portion of telephonic speech can be used to transmit the data. The line is available for the data transmission when a pause of the voice is detected, and the line is blocked for the data transmission during a talkspurt of the voice. Two models of the hybrid transmission system are shown. The first model, in which the data arrive randomly in bursts, is useful to describe a kind of interactive process. The second model, in which the data arrive continuously, describes file transfers, facsimile transmissions, etc. The necessary buffers, the blocking probabilities, the data delay, and other factors of both models are calculated.

This paper describes an optimal logic partitioning/test points setting by using testability measures in large digital circuits. First, signal lines' testability measures (controllability and observability) in a circuit are computed. Next, the circuit is transformed into a network which consists of nodes (corresponding to circuit elements) and arcs (corresponding to signal lines). Then, after the arcs' capacity is defined as a function of the testability measures, the original logic partitioning/test points setting problem for the circuit is transformed into that for the maxflow in the network flows. This problem is solved by using the maxflow/ mincut theorem. Finally, it is shown that a simple logic circuit is considered using the proposed method.

A loop detection is inherent in a context-sensitive parsing. A new detection method is presented for a top-down context-sensitive parsing using a grammar G_E. This method requires only two input items, while the previous one requires three.

A measurement technique of chromatic dispersion in single-mode fiber transmission lines is proposed. By using a local signal generator, an optical line to transmit a reference signal is unnecessary in the proposed measurement technique, even if the input and output end points of the fiber are separated by a large distance.