Abstract: A semiconductor device for an IC tag comprises a receive unit for demodulating receive data from a received RF signal and a signal processing unit for detecting a command comprising data signals from the receive data demodulated by the receive unit and executing processing based on the command, wherein the signal processing unit has a command acceptance mode for detecting the command from the receive data and a command execution mode for executing the command, and cancels the data signal when the data signal is detected from the receive data in the command execution mode.

Abstract: A semiconductor device for an IC tag comprises a receive unit for demodulating receive data from a received RF signal and a signal processing unit for detecting a command comprising data signals from the receive data demodulated by the receive unit and executing processing based on the command, wherein the signal processing unit has a command acceptance mode for detecting the command from the receive data and a command execution mode for executing the command, and generates an error signal when the data signal is not detected from the receive data in the command acceptance mode.

Abstract: A communication system comprises an IC tag, and a reader/writer for performing radio communication with the IC tag. The reader/writer further comprises an encoding unit for encoding a digital signal having at least one bit and generating an encoded signal and a transmission unit for transmitting a modulated wave acquired by modulating a carrier based on the encoded signal during an acceptance period when the encoded signal is accepted in the IC tag, and transmitting the carrier to the IC tag during an execution period when the processing based on the encoded signal is executed in the IC tag. The IC tag further comprises a receive unit for receiving the modulated wave or the carrier transmitted from the reader/writer and a power supply voltage generation unit for generating the power supply voltage based on the received modulated wave or the carrier.

Abstract: A semiconductor device for an IC tag comprises a receive unit for demodulating receive data from a received RF signal and a signal processing unit for detecting a command comprising data signals from the receive data demodulated by the receive unit and executing processing based on the command, wherein the signal processing unit has a command acceptance mode for detecting the command from the receive data and a command execution mode for executing the command, and cancels the data signal when the data signal is detected from the receive data in the command execution mode.

Abstract: A semiconductor device for an IC tag comprises a receive unit for demodulating receive data from a received RF signal and a signal processing unit for detecting a command comprising data signals from the receive data demodulated by the receive unit and executing processing based on the command, wherein the signal processing unit has a command acceptance mode for detecting the command from the receive data and a command execution mode for executing the command, and generates an error signal when the data signal is not detected from the receive data in the command acceptance mode.

Abstract: A semiconductor device, comprises a receive circuit for generating receive data from received radio signals, a power supply voltage generation circuit for generating power supply voltage based on the received radio signals, a control circuit for performing logical processing based on the received data, a transmission circuit for generating radio signals including transmission data and transmitting the radio signals via an antenna and an oscillation circuit, which is operated using the power supply voltage generated by the power supply voltage generation circuit, for generating a predetermined frequency of clocks.

Abstract: An adaptive noise canceling system for improving a S/N ratio and clarity of a output signal includes a delay for delaying the input signal X(j) by a fixed time delay a, a filter for filtering the delayed signal D(j), a subtracter for subtracting the filtered signal Y(j) from the input signal X(j), a coefficients adjuster for adaptively adjusting coefficients of the filter using a least-means-square (LMS) algorithm, a level adjuster for adjusting a level of an error signal .epsilon.(j) which is obtained by subtracting the filtered signal Y(j) from the input signal X(j), and an adder for adding the level adjusted signal .epsilon.(j) to the filtered signal Y(j).

Abstract: A CW (Continuous Wave) radio frequency signal converted to an IF (Intermediate Frequency) signal is mixed with a local oscillator signal by an IF mixer, and the obtained signal is converted to a digital signal by an ADC (Analog-to-Digital Converter). A digital bandpass filter passes only the target component in the output of the ADC. The passed IF signal is demodulated by a digital demodulator, and the demodulated signal is converted to an analog signal before being output as a sound. When pitch control to increase the reception pitch by .DELTA.f is instructed, an MPU (Microprocessor Unit) alters the frequency of the local oscillator signal by .DELTA.f as well as the center frequency of the digital bandpass filter by .DELTA.f, so that the center frequency of the input signal to a narrow-band filter coincides with the center frequency of the digital bandpass filter.

Abstract: A demodulator receives a radio signal and causes a carrier signal reproducing circuit to reproduce the carrier signal of the received signal. One amplifier amplifies the amplitude of the reproduced carrier signal by K, and another amplifies the amplitude of the reproduced carrier signal by (K+2). An adder adds the reproduced carrier signal, amplified by K, and the received signal. A subtracter subtracts the received signal from the reproduced carrier signal amplified by (K+2). The output signal of the adder is demodulated by a first FM demodulator and the output signal of the subtracter is demodulated by a second FM demodulator. Another subtracter outputs the difference between the demodulated signals from the first and second FM demodulators as a demodulated signal of the received signal.

Abstract: The filter coefficients of a digital band pass elliptic filter can be approximated to a linear function of the center frequency of the pass band width. The filter coefficients of a band pass digital filter having a predetermined center frequency and the slope of this linear function are stored in first and second memories. A central processing unit (CPU) obtains the difference between a desired center frequency and a predetermined center frequency. A multiplier multiplies the slope stored in the second memory by the difference obtained by the CPU. An adder adds each of the filter coefficients stored in the first memory to an associated one of the products output from the multiplier. The adding results become the filter coefficients for obtaining the desired center frequency. Those filter coefficients are set in a digital filter.

Abstract: A Single-Sideband (SSB) modulator includes:a demultiplexer for successively distributing an A/D converted digital signal x(t) to L sequences x.sub.1 (t.sub.1), x.sub.2 (t.sub.2)... ...x.sub.L (t.sub.L) in accordance with a sampling period t, an adder including L/2 adders for adding constants to x.sub.i (t.sub.i) of the demultiplexer, where i is either an even or an odd number; a phase shift network system comprising L/2 phase shift networks for making a 90-degree phase difference between the outputs of the adder and x.sub.i (t.sub.i) of the demultiplexer; a timing signal generator for generating timing signals expressed by A(-1).sup.(KL)/2+n and/or A(-1).sup.((K-1)L)/2+n in accordance with the sampling period t; a multiplier including L/2 pair of multipliers for multiplying the outputs of the phase shift network system by the outputs of the timing signal generator; a multiplexer for selecting the outputs of the multiplier in accordance with the sampling period t.

Abstract: The filter coefficients of a digital band pass elliptic filter can be approximated to a linear function of the center frequency of the pass band width. The filter coefficients of a band pass digital filter having a predetermined center frequency and the slope of this linear function are stored in first and second memories. A central processing unit (CPU) obtains the difference between a desired center frequency and a predetermined center frequency. A multiplier multiplies the slope stored in the second memory by the difference obtained by the CPU. An adder adds each of the filter coefficients stored in the first memory to an associated one of the products output from the multiplier. The adding results become the filter coefficients for obtaining the desired center frequency. Those filter coefficients are set in a digital filter.