Canon Kabushiki Kaisha

Norihiro Mochizuki

Koichi Egara

Toshihiko Myojo

Tadashi Eguchi

Akira Torisawa

Kenji Nakamura

Takahiro Hachisu

Tetsuo Kanda

Katsuo Saito

Ichiro Kato

Rie Suzuki

Akihiro Koyama

Hidetada Nago

Kazuo Moritomo

Atsushi Takasaki

Kazuo Yoshinaga

Akane Yokota

Takao Fujita

A receiving apparatus includes a base-band conversion circuit, a synchronizing circuit/code generator and a demodulator. The base-band conversion circuit converts a received signal into a base-band signal. The synchronizing circuit/code generator detects a spread code included in the received signal to generate a plurality of spread codes in synchronization with the spread code included in the received signal. The demodulator uses the plurality of spread codes supplied by the synchronizing circuit/code generator to demodulate the base-band signal.

Spread spectrum receiving apparatus

In a communication apparatus of the transmitting side, n number of parallel signals are respectively spread-modulated by the n number of spreading codes and summation thereof is obtained. Also, m number of parallel signals are respectively spread-modulated by the m number of spreading codes and summation thereof is obtained. These two signals are modulated with quadrature carriers, synthesized and transmitted to the receiving side.

Spread spectrum communication apparatus

A spread spectrum receiving apparatus is constructed by a generator for generating a reference clock, a phase shift circuit for shifting the phase of the reference clock generated by the generator in accordance with a code timing in a reception signal and the reference clock, and a de-spreading circuit for de-spreading the reception signal in accordance with the reference clock whose phase is shifted by the phase shift circuit. The de-spreading circuit generates a code for de-spreading in accordance with the phase shifted reference clock. The phase shift circuit has a calculator for calculating a phase shift amount so as to synchronize the code timing in the reception signal with the code for reception in accordance with a deviation between the code timing in the reception signal and the reference clock.

A spread spectrum reception apparatus generates a local reference code and a timing signal having 1/2 the period of the reference code. Correlation calculation between a received spread spectrum signal and the local reference code is performed. Upon reception of the correlation calculation result, a peak detector detects a correlation peak signal. The rate of a code generation clock is adjusted in accordance with the phase difference between the timing signal and the correlation peak signal to perform de-spread processing of the received signal.

Spread spectrum communication apparatus utilizing a phase difference

A spread spectrum receiving apparatus comprises: a reproducing circuit to reproduce a carrier signal from a reception signal and a diffusion code; a demodulation circuit to demodulate the reception signal into a base band signal on the basis of the carrier signal reproduced by the reproducing circuit; and a judgment circuit to judge the reception data from the base band signal from the demodulation circuit. The reproducing circuit has an operation circuit to arithmetically operate the reception signal and the diffusion code and a detection circuit to detect a difference between the phases of an output of the operation circuit and an output of an oscillator. The oscillator oscillates at a carrier frequency in accordance with a phase difference detected by the detecting circuit.

A surface acoustic wave device includes a piezoelectric substrate, first and second input transducers formed on the substrate and adapted for respectively generating surface acoustic waves corresponding to input signals, the first and second input transducers each having a shape to focus the surface acoustic waves generated thereby, an output transducer formed between the first and second input transducers on the substrate and adapted for obtaining a convolution -signal of the surface acoustic waves generated by the first and second input transducers, and conductive films, one formed between the first input transducer and the output transducer and another between the second input transducer and the output transducer on the substrate. A communication system includes a transmitter for transmitting a signal modulated according to information, a circuit for receiving the modulated signal transmitted from the transmitter, a circuit for generating a reference signal, a surface acoustic wave device, as described above, for outputting a convolution signal of the modulated signal and the reference signal, and a demodulating circuit for restoring the information, using the convolution signal output from the surface acoustic wave device.

Surface acoustic wave device and communication system using it

A surface acoustic wave device includes a piezoelectric substrate, a wave guide path provided on the piezoelectric substrate and an interdigital transducer for exciting a surface acoustic wave. The interdigital transducer is provided with plural portions of mutually different pitches of the electrode finger, respectively corresponding to different frequencies. The portions are parallelly arranged along a direction perpendicular to the propagation direction of the surface acoustic wave. The surface acoustic wave generated by the interdigital transducer is entered in concentrated manner into the wave guide path.

Efficient surface acoustic wave device capable of excitation in plural

A surface acoustic wave device includes a substrate having piezoelectricity, at least two input electrodes, provided on the substrate, for exciting first and second surface acoustic waves, and an output electrode for taking a convolution signal of the two surface acoustic waves out. The substrate has a roughness configuration on a back face thereof and a maximum depth of the roughness configuration is not less than a wavelength of bulk waves of convolution output taken out of the output electrode.

Surface acoustic wave device improved in convolution efficiency,

A demodulation apparatus and a communication system using the same are disclosed. The apparatus comprises code generation means for generating a reference spread code corresponding to a first signal modulated by a spread code, and an elastic surface wave element for receiving the first signal and a second signal output from the code generation means, and outputting a demodulated information signal. The elastic surface wave element comprises a piezoelectric substrate, a first excitation electrode, formed on the piezoelectric substrate, for generating a first elastic surface wave which propagates in a predetermined direction in accordance with the first signal, a second excitation electrode, formed on the piezoelectric substrate, for generating a second elastic surface wave which propagates in a direction opposite to the predetermined direction in accordance with the second signal, and an acousto-electric converter, formed between the first and second excitation electrodes on the piezoelectric substrate, for outputting a convolution signal of the first and second signals on the basis of the first and second elastic surface waves, wherein the acousto-electric converter selectively converts an elastic surface wave having a wave number twice a wave number of the first and second elastic surface waves into an electrical signal.

Demodulation apparatus and communication system using the same

A diffusion code generating method for a code division multiplex communication by a spread spectrum system is provided. A receiving apparatus according to the above method receives the signal which was multiplexed by using a plurality of sets of diffusion codes and comprises: a generator to generate a sync code and a plurality of sets of diffusion codes other than the sync code; a correlator to obtain a correlation between a reception signal and the sync code generated from the generator; and a receiver to receive the reception signal on the basis of the plurality of sets of diffusion codes generated from the generator. The generator generates the sync code in a manner such that the cross-correlation values are set to very small values at positions near a code sync point or are enough smaller than the autocorrelation peak of the sync code or are set to very small values at both of or either one of the positions before and after the code sync point.

Diffusion code generating method for spread spectrum communication

A surface acoustic wave device includes a piezoelectric substrate, an input electrode formed on the substrate and an output electrode formed on the substrate. A surface acoustic wave is generated from the input electrode to propagate in a predetermined direction in accordance with an input signal. In the output electrode, a plurality of taps are arranged in a propagation direction of the surface acoustic wave on the substrate. The surface acoustic wave is converted into an electrical signal by the output electrode. The taps of the output electrode are weighted so that signals output from the taps have substantially equal magnitudes.

Surface acoustic wave device, and demodulation device and communication

A surface acoustic wave element is provided with a piezoelectic substrate, a first input transducer, a second input transducer and an output device such as output electrode. The piezoelectric substrate has a first and a second surfaces which are mutually faced. The first input transducer is formed on the first surface of the substrate to generate a first surface acoustic wave which propagates in a predetermined direction. The second transducer is formed on the first surface of the substrate to generate a second surface acoustic wave which propagates in a direction opposite to the predetermined direction. The output device is formed on the first surface of the substrate to extract a signal produced by an interaction of the first and second surface acoustic waves. At least part of the second surface of the substrate is caused to be inclined in a direction perpendicular to the predetermined direction with respect to the first surface.

Surface acoustic wave element and communication system using the same

In a surface acoustic wave device, there are arranged a piezoelectric substrate, an input electrode and an output electrode. The input electrode is formed on the substrate, and generates a surface acoustic wave propagated in a predetermined direction, in accordance with an input signal. The output electrode is also formed on the substrate, and converts the surface acoustic wave to an electric signal. One of the input and output electrodes includes a plurality of taps equidistantly arranged in a propagation direction of the surface acoustic wave. The other one of the input and output electrodes may comprise a pair of taps arranged at a predetermined distance in the propagation direction. The electrode including a plurality of taps or the electrode including a pair of taps satifies a predetermined relation established among a length between the taps, a transmission speed of the input signal, a propagation velocity of the surface acoustic wave and so forth. According to such a structure, two bits of the signal can be processed without a delay circuit. A demodulating device and a communication system respectively include the surface acoustic wave device so that a circuit structure can be simplified and that data can be reproduced with a high signal quality.

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Yokohama, Japan

Norihiro Mochizuki