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.