A new depth measurement method is described in this paper. This method uses the parallel planes of light each of which flickers in the time domain according to the binary code uniquely assigned to it. When the code length is ⁿ bits, we input ⁿ pictures projected on a certain object in which we locate and "identify" each slit image. Then the depth to the points on the slit images can be calculated by triangulation. The experimental results show that this method is faster and stronger for noise than the conventional methods. We aim to investigate the importance of knowledge about the task domain being used in signal level processing. Picture processing systems are usually task dependent, so the knowledge about the domain can be applied even in signal level processing. The knowledge is, we believe, more powerful to be used at earlier stage in picture processing than to be used at the latter one. A result about the transformation from knowledge to signal-to-noise ratio is shown as an example.

In order to develop a light and small sized fusion splice machine operating from a small battery, a new high frequency discharge method with high voltage trigger has been developed. The method uses a high voltage trigger at the beginning of discharge to reduce power consumption. It was found experimentally that the voltage of an A-C discharge depends vastly on the applied voltage waveform. To use a high voltage trigger method effectively, pertinent applied voltage conditions were found considering the ion movement. By adopting pertinent conditions, the power consumption for discharge reduces to 1/5 of that for the conventional discharge method. The new method is adopted for developing a fusion splice in optical fibers. The developed machine is 2.5 kg in weight including battery, and consumes 25 watts electric power. The average splice loss and splice tension strength are 0.03 dB and 480 g, respectively.

A refractive-index profile formation mechanism in the VAD method for optical fiber preform fabrication was investigated and practical techniques for precisely controlling the preform index profile are proposed. The GeO₂ dopant distribution in the preform is found to be mainly caused by the porous VAD preform surface temperature distribution and by the raw material vapors mixing effect. By applying the surface temperature effect, the index profile can be controlled in the wide profile parameter range of d1-10. Further, by utilizing the maxing effect, it is possible to adjust the profile parameter precisely around a desired value. Transmission characteristics for graded-index fibers obtained with the above control technique are also presented.

When realizing a high-quality land mobile radio transmission system, one of the most important and difficult problems is how to mitigate the multipath fading effect which degrades the signal transmission performance severely. Transmitter diversity without any feedback signal transmission link is the most effective technique, because mobile radio units can be simply implemented. This paper proposes a new transmitter diversity suitable for digital land mobile radio transmission systems using MSK with differential detection. More than two MSK signals carrying the same information are transmitted simultaneously from separate antennas, received combiningly by a single receiver antenna, and demodulated by the conventional differential detector. After describing the diversity principle, bit-error-rate (BER) performance improvement effect is theoretically analyzed and experimentally confirmed by the laboratory simulation tests.

The class of languages generated by unary TOL systems with regular control is considered and investigated. It is shown that the equivalence problem for unary TOL systems with ultimately periodic regular control is decidable. The problems for other versions of unary TOL systems are discussed.