Clarion Co

Shigeo Akazawa

Masahiro Hamatsu

Masaharu Mori

Yoshitaka Uchida

Mamoru Endo

Takeshi Hashimoto

A spread spectrum receiver includes, for example, a correlator consisting of two convolvers whose correlation outputs are applied to a demodulator respectively via two variable gain amplifiers whose gains are controlled in response to a demodulation output from the demodulator.

Automatic gain control system

On the transmitter side, data to be transmitted are converted into a plurality of parallel data sets by a serial-parallel converter 101 and spread spectrum modulation is effected by means of PN code generators 105 and selectors 102. Each of the modulated outputs is delayed by a delaying circuit 103 with reference to a sounder channel and the phase thereof. The output thus delayed and the output of the sounder channel are added by an adder 104 to be multiplexed and transmitted. On the receiver side, correlation between a received signal and a reference signal is formed by a correlator 201 to obtain a correlation pulse from the correlation output thus obtained. Data demodulation is effected by means of a sounder detecting circuit 209, a sampling pulse generating circuit 210 and an information detecting circuit 211, starting from this correlation pulse. According to the structure described above, in SS communication, data demodulation can be effected with a high efficiency by using a single correlator.

Spread spectrum communication device

On the transmitter side of a spread spectrum communication device according to the present invention, transmission date are converted into a plurality of parallel data sets by a serial-parallel convertor and spread-spectrum-modulation is effected by means of PN code generators and selectors. Different modulated outputs are delayed by delay devices, using a sounder channel and the phase thereof as a reference. The delayed outputs and the output of the sounder channel are added by an adder, multiplexed and transmitted. On the receiver side correlation of a received signal with a reference signal is formed by a correlator and a correlation pulse is obtained from the correlation output. Data are reproduced by means of a sounder detecting circuit, a sampling pulse generating circuit and an information detecting circuit. In this way data reproduction can be effected with a high efficiency by means of a single correlator.

In a spread spectrum communication device it is intended to simplify a circuit and to realize cost down by controlling the gain of correlation spikes on the basis of a peak value held by a peak value holding circuit in a correlation pulse generating circuit.

Automatic gain control device for spread spectrum communication device

A multiplex communication device by the spread spectrum communication system is disclosed, in which a reference signal and a plurality of information signals are multiplexed to be transmitted after having spreading-modulated each of them, and data demodulation for the plurality of information signals is effected on the basis of a correlation-demodulated reference signal by executing correlation operation of this multiplexed received signal with a reference signal by means of a single correlator.

A carrier sense circuit for sensing a carrier component of a received signal in a spread spectrum system includes a multiplier which produces a squared signal by multiplying the received signal by itself, a filter which extracts from the squared signal a carrier component of a spread spectrum signal included in the squared signal, and a detecting circuit which detects the level of the carrier component and which outputs a carrier sense signal when the level of the carrier component is greater than a predetermined level. The filter is a band pass filter having a central frequecny of 2f.sub.c where f.sub.c is the central frequency of the spread spectrum signal. Where the spread spectrum system includes an initial synchronization circuit, and a correlation arrangement which correlates the received signal with a reference signal to produce correlation pulses, a circuit can be provided to start the initial synchronization circuit in response to simultaneous occurrence of the carrier sense signal and one of the correlation pulses.

Spread spectrum receiver and carrier sense circuit therefor

A spread-spectrum communication receiver uses two convolvers and a phase shifter to demodulate data from correlation outputs of the convolvers. The demodulated output is used to control the phase-shifting amount of the phase-shifter and gains of the correlation outputs.

Spread-spectrum communication receiver

A phase shifter is disclosed which performs a desired phase shift by distributing an input signal to two signals whose phases are different by 90.degree. from each other which signals are added to each other after having been weighted with a sine and a cosine function signal, the sine and the cosine function signal being able to be set in a digital manner.

Spread spectrum receiver having phase shifter for effecting phase

A receiver for spread spectrum communication is disclosed, which is provided with two convolvers and in which a first and a second reference signal, each of which consists of a 4-phase-modulated signal formed on the basis of a first PN code, a second PN code and a first CW signal, are supplied to a second input of each of the convolvers, respectively, while a received signal is supplied to a first input of each of the convolvers so that the correlation output of each of the convolvers is decoded so as to obtain an information signal.

Receiver for spread spectrum communication

A receiver for spread spectrum communication decoding spread spectrum signals so as to obtain data by correlating a same received signal given to a first input of each of the convolvers constituting a correlator with two reference signals given to the other input of each of the convolvers, is disclosed, in which a phase shifter is disposed on the other input side of either one of the convolvers and the phase shifter generates one of the two reference signals having a predetermined phase difference with respect to the other.

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Tokyo, Japan

Shigeo Akazawa