Mitsubishi Denki Kabushiki Kaisha

Tatsuya Uchiki

Toshiharu Kojima

Seiji Okubo

Hiroyasu Sano

Makoto Miyake

A spread spectrum transmitter provides delays having different magnitudes to spread spectrum (SS) signals for a plurality of channels, and multiplexes the SS signals to generate transmission multiplex SS signal. A spread spectrum receiver calculates a partial correlation value between the transmission multiplex SS signal and spreading codes multiplied to the SS signals, multiplies the partial correlation values by a prescribed matrix prepared based on each orthogonal code sequence to calculate a plurality of orthogonal correlation values. The receiver identifies for a respective channel each parallel data sequence related in advance to an orthogonal code sequence whose orthogonal correlation value is a maximum, corrects delay differences of the parallel data sequences, and then performs sampling and parallel-serial conversion to obtain a serial demodulated data sequence.

Spread spectrum transmitter and spread spectrum receiver

A spread spectrum transmission apparatus includes, a chip clock generation section which outputs a chip clock in one frame formed of M+L&#x2212;1 chips, a frame clock generation section which outputs a frame clock synchronized to frame occurrence timing, SS-PPM signal generation sections each of which inserts a pseudonoise code sequence corresponding to one period from some of M chips located at a head of a frame based on K-bit transmission data and generates an SS-PPM signal, delay sections which respectively delay N SS-PPM signals respectively by determined delay quantities, and a multiplexing section which adds up all of outputs respectively of the delay units and generates a multiplexed SS-PPM signal.

Spread spectrum transmission apparatus, spread spectrum reception apparatus, and spread spectrum communication system

A typical Viterbi decoder having a coherent detection function suffers from degraded performance under certain fading-induced phase shift conditions when used in a time diversity system. This problem is resolved by providing a demodulator for demodulating a data sequence multiplexed by multiplexing a plurality of data sequences of a same content with a time difference inserted therebetween for a time diversity system, which comprises: a phase correction unit for phase correcting the multiplexed data sequence; a diversity combiner for demultiplexing the multiplexed data sequence output from the phase correction unit into a plurality of data sequences, removing the time difference inserted between data sequences, and combining the data sequences; and a Viterbi decoding unit for Viterbi decoding the diversity combined signal from the diversity combiner.

Demodulator and communications system

An adaptive array communication system includes an adaptive control unit ( ) which performs a weighting process by multiplying received signals from a plurality of antennas by complex weights which are different from each other for respective states to combine the received signals, a decoding unit ( ) which calculates a metric corresponding to a transition to a desired state, and an error vector calculation circuit ( ) which calculates an error vector for calculating complex weights which are different from each other for the respective states.

Adaptive array communication system and receiver

In a communication system using the time diversity transmission scheme, the communication system provided with the stable automatic frequency control circuit with the wide frequency pull-in range and under low CN ratio transmission is achieved by removing the modulation phase from the received data through the application of the data correlation of the time diversity. The frequency offset in the received signal is compensated as the phase rotator rotates the phase of the received signal, the phase converter converts the phase rotator output into a phase, the serial-to-parallel converter converts the phase converter outputs into serial-to-parallel sequence, the delay units gives a delay to the serial-to-parallel converter output, the phase adder adds the serial-to-parallel converter output to the delay unit output, the multiplier multiplies the phase adder output by a certain value, the integrator integrates the multiplier output, another integrator integrates the integrator output, and the phase rotator controls the phase of the received signal based on the other integrator output.

Automatic frequency control communication system

In the communication system using the binary phase shift keying (BPSK) modulation method, an erroneous data that might be caused by a carrier slip of carrier wave generated during coherent detection can be compensated. The modulation unit of the transmitter transmits identical data at differentiated timing through BPSK modulation, and the coherent detector circuit of the demodulation unit of the receiver detects waves upon receiving signals. The compensating circuit makes time differences in transmitted data equal and compares them to detect mismatch in order to compensate carrier slip found in the received signal and then the combination circuit realizes the combination.

Carrier slip compensation method for coherent detection

A synchronization determining method and circuit for determining a synchronization state of a multiplexed data stream derived by multiplexing a plurality of data streams having the same contents with a time lag provided therebetween, wherein the synchronization determining circuit establishes synchronization without decreasing transmission efficiency, generating incorrect code sequences, or increasing overall circuit scale. In each embodiment of the present invention, synchronization is established without using synchronization words. Because synchronization is achieved without feedback loop delay, incorrectly decoded sequences are not generated for a period of time before synchronization is established. Also, because no maximum pass metric state detecting circuit is required, circuit scale, power consumption, and operating speed can be improved.

Synchronization determining circuit, demodulator and communication system

A receiver, an automatic gain controller suitable for the receiver, a control signal generator suitable for the automatic gain controller, a reception power controller using the automatic gain controller and a communication method using the receiver. The instantaneous power of a received signal output from a variable gain amplifier or attenuator is detected by a power detector. The detected instantaneous power is quantized by a comparator and filtered through a random walk filter. An up-down counter counts up or down in accordance with the increment signal or the decrement signal obtained by filtering. In this manner, error in the gain control of the variable gain amplifier or attenuator is obtained.

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Tokyo, Japan

Tatsuya Uchiki