Abstract: A spectrum diffusion signal including data representing a center frequency of an acoustic surface filter in a transmitter side is transmitted with its carrier-frequency being swept. When a receiver side receives a modulation signal, a spectrum diffusion signal including data representing a center frequency of an acoustic surface filter in a receiver side is transmitted on the carrier-frequency equal to the center frequency of the surface acoustic wave matched filter in the transmitter side included in the modulation signal. Thereafter, the transmitter side transmits spectrum diffusion signals having the carrier-frequency equal to the center frequency of the surface acoustic wave matched filter in the receiver side included in the modulation signal.

Abstract: A code division multiple access apparatus which is capable of high-speed synchronization, is simple in construction and, moreover, achieves reduced consumption of electric power during standby. When a specific pattern contained in a signal received by a receiving antenna is detected by a SAW matched filter, a correlation peak is output from the filter. A bit synchronization signal generating circuit detects the correlation peak thereof and generates a synchronization signal after a set time has elapsed from the detection of the correlation peak. An orthogonal PN code generator generates a predetermined orthogonal PN code in accordance with the synchronization signal. Further, a carrier generator generates a carrier in response to the output of the SAW matched filter. This generated carrier is modulated by the output of the orthogonal PN code generator.

Abstract: A radio IC card system includes an IC card and a toll collector. When an automobile with the IC card passes by a tollgate, the toll collector installed in the tollgate transmits a first radio signal which is spread modulated using a pseudorandom noise (PN) code from an antenna. The first radio signal is received by the antenna of the IC card and is transmitted to a surface acoustic wave (SAW) correlator. The SAW correlator extracts a PN code included in the received signal, and outputs a peak signal. An accumulation circuit accumulates the peak signal. A threshold discharger is activated to switch on a relay switch when the output voltage of the accumulation circuit exceeds a constant value. Thereby, the voltage of a battery is supplied to a data communication unit. Then, the identification code of the IC card and a record of tollgates by which the automobile has passed are transmitted via radio signal to the toll collector.

Abstract: A radio data transmitter includes radio switching circuit which is activated in response to first radio signal having a predetermined particular pattern, and a data transmitter unit. The data unit transmits a first radio signal include a carrier modulated by predetermined data from an antenna when supplied with power in accordance with the activation of the radio switching circuit, and subsequently disconnect the power supply. In addition, a radio data receiver includes switch-activation to circuit for transmitting the first radio signal having the predetermined particular pattern, a receiving circuit for receiving the second radio signal including the data from the data transmitter unit activated by the first radio signal having the predetermined particular pattern, and a storage device for storing data received by the receiving circuit.

Abstract: A radio switching apparatus is provided which is actuated upon reception of a radio signal and which is capable zero or near-zero standby electric power consumption. The radio switching apparatus includes a receiving antenna; a surface-acoustic-wave device to which a signal received by the antenna is fed and which extracts a specific pattern contained in the signal; a storing circuit for storing output electric power of the surface-acoustic-wave device; and a switch circuit which is turned on when the output voltage of the storing circuit exceeds a set value.

Abstract: In a spread-spectrum communication apparatus using a convolver as a correlator, demodulating processes in a receiver apparatus using a carrier and a PN code are performed under a non-synchronous condition.

Abstract: An acoustic surface wave device includes a substrate made of an elastic material, a multilayer structure disposed on a surface of the substrate and having a silicon dioxide layer and an aluminum nitride layer superimposed on each other, and electrodes having predetermined configurations formed on the multilayer structure. The main component of the elastic material is a silicon monocrystal, whose temperature coefficient of delay time for acoustic surface waves is positive, and the piezo-electric axis of the aluminum nitride is either perpendicular or parallel to the surface of the substrate, with a negative delay coefficient, counteracting that of the substrate.

Abstract: A surface acoustic wave device comprises an elastic substrate having a major surface with a given crystal orientation and having a positive temperature coefficient of delay (TCD), and AlN film deposited on the elastic substrate so that piezoelectric axis of the AlN film has a predetermined direction with respect to the major surface of the elastic substrate having a negative TCD, and electrodes provided on the AlN film or between the elastic substrate and the AlN film.