Tetsudo Kizai Kogyo Company Limited

Nippon Electric Co., Ltd.

Nec Corporation

Yoshio Matsuo

Kentaro Matsubara

Yukitsuna Furuya

Yoshihiko Akaiwa

Junji Namiki

Yoshinori Nagata

Yasuo Kato

In order to achieve the spectrum economy and reduce the power consumption of a transmitter and reduce the error rate at a receiver and simplify receiver circuitry, at least one bit stream to be transmitted is quadrature modulated in a manner that the signal points do not define a trace on a complex amplitude plane which passes through the origin of the plane coordinates or in the vicinity thereof. The received signal is hard limited and frequency-discriminated to determine the instantaneous angular velocity of the received signal and is integrated to detect the phase variation between two consecutive received signals, and thereafter is decided with respect to the phase variation according to the decision threshold levels 0 and .+-..pi. radians.

Digital radio communication system utilizing quadrature modulated

A rail fastening device comprises a curved tapered spring having free ends adapted to engage a rail flange for preventing lateral and tilting motion of the rail. The spring is secured by a fastening element having a detent which is rotated and slid into a shaped hole in an anchor embedded in the tie on which the rail is supported.

Rail fastening device

A cam actuated elastic rail securing device comprises a spring member which is adapted to engage the flange of a rail and to cooperate with a rotary cam element to apply an elastic restraining force to the rail when the cam is rotated relative to an anchor and slid axially to lock the cam against reverse rotation.

Cam type elastic rail fastening device

An elastic rail fastening device for securing a rail to a concrete tie having a spike secured therein. A top pressing spring engages the top surface of the rail flange for holding the rail against the tie. One end of the spring is supported beneath a shoulder on the metal spike. A spring receiver is fitted to the tie, and the other end of the top spring bears thereagainst. A side spring is inserted between the side of the rail flange and the spring receiver to receive transverse pressure working on the rail.

Elastic rail fastening device

An elastic rail fastening device which uses a metal spike having a projecting jaw, the lower part of the spike being buried in a concrete support. A deformed S-shaped plate spring is provided with one end contacting the upper surface of a spring receiver, a first bent-down portion urged downwardly for depressing the upper surface of the rail flange as laid on the concrete support, a middle portion having the upper surface contacting the projecting jaw, a second bent-down portion for contacting the side of the spring receiver, and the other end contacting the side of the rail flange. The spring receiver is interposed between a guide on the concrete support and the second bent-down portion, whereby the spring receiver pushes up the one end of the spring.

A low level initial acquisition signal consisting of a continuous wave signal portion followed by a phase-modulated signal portion is transmitted via a satellite to a receiving station. The received CW signal is converted by a voltage-controlled variable frequency local oscillator to an intermediate frequency signal which is fed to a narrow passband filter. The local oscillator frequency is linearly swept, and the maximum signal passing through the filter during one sweep is detected. The local oscillator is then locked at the local frequency which produced the maximum signal, thereby effecting frequency acquisition. Next, the phase-modulated signal portion is multiplied by a phase-modulated signal output from a variable phase local signal generator. The phase of the local generator is also swept, and the maximum phase correlation signal passing through the band pass filter is again detected, and the phase of the generator output is corrected by the phase shift which produced the maximum phase correlation signal. This phase shift is used as a basis for determining the proper timing for acquisition of the correct time slot in the TDMA frame at the satellite for a transmitted data burst. The acquisition is confirmed by comparing the maximum phase correlation signal obtained during phase sweeping with the signal level obtained after the phase of the generator has been locked.

Initial acquisition signal detection system for TDMA satellite

A rail fastening apparatus for cooperation with a rail which is supported on and extends transversely across a tie. The apparatus comprising a steel support positioned adjacent one side of the rail and having a leg portion which is buried in the tie and an upper portion which projects upwardly above the tie. A lever is pivotally supported on the upper portion for swinging movement about an axis which extends substantially parallel with the longitudinally extending direction of the rail. The lever has a cam associated therewith. A spring-receiver structure is mounted on the tie and positioned on the opposite side of the axis from the rail, and an elongated plate-like spring extends between the spring-receiver structure and the rail. The spring has one end supported on the spring-receiver structure and the other end supported on a flange of the rail. The spring is disposed below the lever and positioned so that the cam is adapted for engaging a central portion of the spring, whereby rotation of the lever causes the cam to engage the spring and resiliently deflect same downwardly to thereby press the rail securely against the tie.

Rail fastening apparatus

A compact transmitter-receiver circuit particularly adapted for short-distance mobile communication includes a pair of parallel nonlinear circuits, first and second hybrid circuits connected to the pair of nonlinear circuits on their high- and low-frequency sides, respectively, and a radio-frequency generator and a driver circuit connected to the respective hybrid circuits. One of the four terminals of the first hybrid circuit serves as a common input-output terminal of the transmitter-receiver circuit without necessitating any particular means conventionally required for separation between transmission and reception signals.

Transmitter-receiver circuit

Amplitude-and-phase modulated signals, as received, are represented by corresponding points on a reference signal plane of points to which results of demodulation, phase errors, and amplitude errors are preliminarily assigned. Responsive to the received signals, a detector produces position signals representative of the corresponding points. Responsive to the position signals, a demodulation and error-detection circuit produces result signals, phase error signals, and amplitude error signals representative of the results of demodulation, phase errors, and amplitude errors assigned to the corresponding points. Responsive to control signals specifying a predetermined area of the reference signal plane and to the position, phase error, and amplitude error signals, a selection circuit produces phase and amplitude control signals, which correct the reference signal plane to reduce the phase and amplitude errors of the position signals. After correction, the result signals become the demodulated signals.

Demodulator for amplitude-and-phase modulated signals having control

A monitor for a receiver specifies a predetermined region within each of a plurality of continuous discrimination domains of a signal space, with each domain including a true signal point representative of an original signal which the receiver may allowably receive. The monitor compares each of the regions to the actual signal points represented in the receiver input signal and produces a monitor output signal representative of the frequency at which the actual signal points of the received signal are outside of the predetermined regions.

Growing community of inventors

Tokyo, Japan

Yoshio Matsuo