Clarion Co

Nippon Electric Co., Ltd.

Masaharu Mori

Masahiro Hamatsu

Kiyoshi Amazawa

Shigeo Akazawa

Shigeru Takeuchi

Motohiro Gochi

Shoichi Minagawa

Yoshitaka Uchida

Takashi Taniyama

Masahiro Tsuchiya

Kouichi Tanaka

Takao Kurihara

Ryuichi Asai

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

In a spread spectrum communication system for communicating data by spreading spectrum, thereof, using PN codes, on the transmitter side, a first modulated output portion, which is spread-spectrum-modulated, containing no data to be transmitted and a second modulated output portion, which is spread-spectrum-modulated, following the first modulated output portion and containing data to be transmitted are generated; and the second modulated output portion is transmitted with a low electric power and the first modulated output portion with a high electric power. On the receiver side, a correlation-demodulated output is generated by correlation-demodulating a received input; and from the correlation-demodulated output consisting of a first correlation-demodulated output portion corresponding to the first modulated output portion and a second correlation-demodulated output portion corresponding to the second modulated output portion the first correlation-demodulated output portion is detected. Further timing signal serving as a reference for an operation on the receiver side is generated, starting from the first correlation-demodulated output portion.

Spread spectrum communication device

In a spread spectrum communication system for communicating data by spreading spectrum thereof, using PN codes, on the transmitter side, a first modulated output portion, which is spread-spectrum-modulated, containing no data to be transmitted and a second modulated output portion, which is spread-spectrum-modulated, following the first modulated output portion and containing data to be transmitted are generated; and the second modulated output portion is transmitted with a low electric power and the first modulated output portion with a high electric power. On the receiver side, a correlation-demodulated output is generated by correlation-demodulating a received input; and from the correlation-demodulated output consisting of a first correlation-demodulated output portion corresponding to the first modulated output portion and a second correlation-demodulated output portion corresponding to the second modulated output portion the first correlation-demodulated output portion is detected. Further timing signal serving as a reference for an operation on the receiver side is generated, starting from the first correlation-demodulated output portion.

A spread spectrum communication device according to the present invention includes a transmitter and a receiver, and suppresses demodulation errors to a minimum value, even if there exit a plurality of narrow band disturbing signals. In the transmitter, a first PN (pseudo noise) code from a fist PN code generator and a second PN code having a delayed phase coming from a shift register are inputted to a multiplexer and switched according to an exclusive logic sum of data and a disturbing signal. The multiplexer output is modulated by a modulator so that it can be transmitted. In the receiver, a correlation output from a correlator is detected by a detector and a detection output thereof is digitalized by a voltage comparator. A correlation pulse thus obtained is applied to two AND gates. Two time window pulses are each applied to two multiplexers nd are switched by a control signal, the outputs of the multiplexers being respectively applied to these AND gates. Pulses from these AND gates are counted by an up-counter and a down-counter in a demodulating circuit to demodulate the data.

A spread spectrum receiver using a correlator is disclosed, in which first and second comparing means comparing a correlation spike coming from the correlator with a first and a second reference voltage are used, the reference voltages being regulated, depending on the output of the first comparing means so that variations of the correlation spikes are followed precisely to obtain a two-valued correlation pulse.

Spread spectrum receiver

A spread spectrum receiver using a correlator includes a pattern matching circuit for deciding presence or absence of a pulse output which is obtained upon coincidence between the pattern of a correlator output and a predetermined pattern, so as to switch a PN code inside the receiver or the center frequency of a received signal when absence of the pulse output is acknowledged.

The present invention is a spread spectrum communications system where the plural pseudonoise codes are switched such that one pseudonoise code represents binary '1' and another pseudonoise code represents binary '0' of the binary data to be transmitted. Further, in the receiver, a reference pseudonoise code is generated which is asynchronous with respect to the carrier and with respect to the pseudonoise codes of the transmitter. The reference pseudonoise code is used in a convolver to reproduce the transmitted information signal.

A correlation pulse generator used in a receiver of a spread spectrum communication system comprises peak hold circuit for holding peak values of positive and negative correlation spikes, threshold setting circuits for generating thresholds based on the peak values, and a comparing circuit for comparing the threshold with a correlation spike to generate a correlation pulse, so that when a level difference exists between positive and negative correlation spike levels of a correlation output, their peaks can be held independently, and thresholds based on the peaks can be generated independently.

Spread-spectrum receiver

A spread spectrum communication receiver is disclosed, which is provided with a correlator for correlating a received PN code contained in a received signal with a reference PN code contained in a reference signal generated on the receiver side, the output of which is given to pattern judgment means such as a matched filter, etc., and an operation of the initial synchronization of the two PN codes in the correlator is effected by using a judgment output obtained when the pattern of the output of the correlator is in accordance with a predetermined judgment pattern.

Spread spectrum communication receiver

An integrating circuit is configured to feed a correlator output to a first integrating and dumping circuit and to a second integrating and dumping circuit and to subsequently add their respective outputs in a composing circuit. The first integrating and dumping circuit and the second integrating and dumping circuit are activated selectively by a switching control switch to perform their integrating and dumping operations.

Integrating circuit

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 spread spectrum receiver including a convolver for establishing initial synchronization of received and reference pseudo noise codes and a delay lock circuit or other circuit for subsequently tracking the phase difference between both pseudo noise codes includes a delay adjuster which is provided between a reference pseudo noise code generator and a code phase adjuster for supplying the reference pseudo noise code generator with a control signal to delay the control signal in order to eliminate a variety of the delay time of the convolver and influences of the temperature characteristic.

Growing community of inventors

Tokyo, Japan

Masaharu Mori