Abstract: A system for communicating between mobile units and an exchange station, with a radio frequency signal, in which an electric signal from a telephone exchange of the telephone station is converted into an optical signal with an electricity-to-light converter. The optical signal is carried via an optical fiber cable to a transmission communication antenna for emission, with amplification of the optical signal if necessary. The emitted signal is received by a receiving communication antenna, amplified with an optical amplifier if necessary, and converted to an electric signal with a light-to-electricity converter.

Abstract: An optical transmitter for providing a signal light with a reduced degree of polarization, the transmitter being used as a transmitting terminal of an optical repeater system that encompasses optical amplifiers at a signal light transmitter, the optical transmitter includes an optical source for transmitting a signal light source; and a degree of polarization reducing circuit including a polarizing beam splitter splitting the signal light source from the optical source means into a first polarized component and a second polarized component that are orthogonal to each other; a first optical path transmitting the first polarized component input from the polarizing beam splitter while maintaining the polarization plane of the first polarized component; a second optical path, which is spatially separate from the first optical path, transmitting the second polarized component input from the polarizing beam splitter while maintaining the polarization plane of the second polarized component; and a polarizing beam mi

Abstract: This invention relates to a method of recognizing input speech of many unspecific people. Feature parameters representing both a short-time average spectrum envelope characteristic of the input speech, and regression coefficients obtained from the outputs from a wide-band filter bank. The regression coefficients represent the rough directionality of the characteristic of change in the spectrum of the speech signal. Distance is measured between the feature parameters and standard patterns stored in a storage means. The distance between the feature parameters and the stored pattern which is smallest of all the patterns is found to recognize said input speech.

Abstract: Differential data signal transmission technique, providing a differential data signal transmission technique inclusive of the correcting factor that requires no transmitter/receiver other than the GPS receiver, comprises the use of a differential ranging system where spread spectrum signals (SS signal) are multiplied at the same frequency, transmission rate, and modulation method used by the GPS satellites, but with different codes from those used by the GPS satellites, the SS signals used to transmit correcting factor from an earth station on the ground to a mobile station on the ground carrying a GPS receiver via a geostationary orbit satellite or a low earth orbit satellite.