Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A surface acoustic wave device comprises a piezoelectric substrate, a plurality of input transducers, formed on the substrate, for generating surface acoustic waves corresponding to input signals, a plurality of waveguides which are juxtaposed on a region of said substrate where the surface acoustic waves generated by said input transducers overlap each other, and in which signals are generated due to an interaction of the surface acoustic waves, the waveguides generating surface acoustic waves corresponding to the signals due to the interaction, and an output transducer for receiving the surface acoustic waves generated from the waveguides, converting the signals due to the interaction into electrical signals, and extracting the electrical signals, the output transducer being constituted by a plurality of portions, juxtaposed in a widthwise direction of the surface acoustic waves generated from the waveguides, for receiving some components of the surface acoustic waves generated from the waveguides, and outp

Abstract: A surface acoustic wave device comprises a substrate, a plurality of input transducers formed on the substrate for generating first and second surface acoustic waves propagating in opposite directions to each other, and a plurality of waveguides arranged in a direction orthogonal to the propagating direction of the first and second surface acoustic waves on a region where the first and second surface acoustic waves overlap. Each waveguide producing a third surface acoustic wave propagating in a direction where the waveguides are arranged, with the interaction between the first and second surface acoustic waves, and on at least two of the waveguides, third surface acoustic waves reflected at respective side edges cancel each other, and an output transducer converts the third surface acoustic waves propagating from the waveguides into an electrical signal.

Abstract: An elastic surface wave convolve comprises a piezoelectric substrate, a plurality of input transducers formed on said substrate for generating elastic surface waves corresponding to respective input signals, a plurality of waveguides provided side by side on a region of the substrate where elastic surface waves radiated from the input transducers overlap, wherein a convolution signal of input signals is produced due to parametric mixing effect of elastic surface waves in respective waveguides, these waveguides generating an elastic surface wave corresponding to the convolution signal, and an output transducer for receiving the elastic surface wave radiated from the waveguides and taking out an electrical signal by conversion of the convolution signal, wherein the width of elastic surface wave radiated from the waveguides is narrower immediately before reception with the output transducer than immediately after radiation from the waveguides.

Abstract: A surface acoustic wave convolver comprises:a piezoelectric substrate:plural input transducers formed on the substrate and adapted for respectively generating a surface acoustic wave corresponding to an input signal; andan output transducer for interferring thus generated surface acoustic wave and obtaining a convolution signal of the input signal from a surface wave generated by thus interfered surface acoustic wave, wherein the output transducer is formed by first and second output electrodes provided in parallel manner between the input transducers and having mutually different lengths along the propagating direction of the surface acoustic wave.

Abstract: In a surface acoustic wave elastic convolver capable of showing sufficiently high convolution efficiency with a simple structure, the convolver comprises a piezo-electric substrate, plural input transducers formed on the substrate for respectively generating surface acoustic waves corresponding to input signals, an output transducer for obtaining a convolution signal of the input signals, from a surface acoustic wave generated by non-linear interaction, of the surface acoustic waves generated by those input transducers, and a dielectric film of a non-linear effect larger than that of the substrate, formed on the substrate in at least an area where the output transducer is formed.