Nec Corporation

Kazuo Ogoro

Satoshi Niwa

A portable wireless terminal and a moving velocity detecting method for the portable wireless terminal capable of detecting a moving velocity with high accuracy without increasing power consumption and terminal cost are provided. At the start of a communication, GPS reception-related circuitsandare turned on, an initial position of a portable wireless terminalis detected, a RAKE receiverand a synchronous detectormeasure Doppler shift amounts of down signals at a known frequency received from a plurality of base stations, respectively, and a CPUcalculates relative velocities of the portable wireless terminalto the respective base stations and obtains a current moving velocity of the portable wireless terminalfrom positions of the base stations, the initial position, and the relative velocities. The current position is calculated from the initial position and the current moving velocity, and sequentially updated to be used in place of the initial position at the time of calculating the moving velocity next time. The initial position at the start of the communication may be obtained by using a W-LAN, an RFID system, a wireless IC card or user input information instead of using a GPS.

Portable wireless terminal and moving velocity detecting method for portable wireless terminal

Disclosed are an apparatus and a method for the adjustment time for IQ offset of a quadrature modulator of a transmission circuit. In adjusting the I-offset and the Q-offset of a quadrature modulator, supplied with an I-signal and a Q-signal output from an analog baseband unit to modulate a carrier. Set-up values of the I-offset and the Q-offset, associated with at least three different points on an IQ offset correction plane having an I-component and a Q-component as X- and Y-coordinates, are set for the analog baseband unit at respective different set-up timings. The values of the carrier leak level, associated with three-point offset set-up values of the output signal of the quadrature modulator, are acquired by a sole measurement operation. From the measured values of the three-point carrier leak levels, the values of the carrier suppression ratio for the three points are found from the measured values of the three points of the carrier leak level to find the optimum set-up values of the I-offset and the Q-offset.

Apparatus and method for adjusting quadrature modulator, communication apparatus and program

A portable cellular phone system with an automatic answering telephone function can perform data communication and has automatic answering telephone functions installed on both the network side and a terminal unit side. This system includes a section for transferring a message recorded first by the automatic answering telephone function on the network side to the terminal unit side.

Portable cellular phone system with automatic answering telephone function

An electronic apparatus with backlit display and input device allowing reduced power consumption while maintaining necessary brightness is disclosed. A mode detecting section detects a currently set operation mode when performing a function. The brightness of the backlighting is controlled depending on the currently set operation mode. In the case of a data input mode, the brightness of the backlighting is reduced.

Electronic apparatus with backlighting device

A digital signal processor (DSP) control apparatus includes a DSP, estimation unit, calculation unit, and clock generator. The DSP performs digital signal arithmetic processing using a clock having a variable frequency. The estimation unit estimates an arithmetic processing amount of the DSP. The calculation unit calculates a new clock frequency on the basis of an estimated arithmetic processing amount from the estimation unit. The clock generator supplies a clock having a frequency calculated by the calculation unit to the DSP.

DSP control apparatus and method for reducing power consumption

An impedance-matching method for matching impedances of first and second circuits at two or more frequencies by using an impedance-matching circuit including reactance elements is provided, which makes it possible to set the impedance of two circuits to be connected at an optimum value or values at the frequencies. In the first step, reactance circuits equivalent to the individual reactance elements of the impedance-matching circuit are configured. Each of the reactance circuits comprises reactance elements and has a frequency characteristic giving desired reactance values at the two or more frequencies. In the second step, reactance values of the reactance elements forming each of the reactance circuits configured in the first step are calculated. In the third step, impedance values of the impedance-matching circuit at the two or more frequencies are determined by using the reactance circuits having the calculated reactance values in the second step, thereby equalizing the impedances of the first and second circuits to their optimum value or value. Each of the reactance circuits comprises a parallel or series resonant circuit having a resonant frequency located between two adjacent ones of the frequencies.

Impedance-matching method and circuit at different frequences

A received input signal 10 is received by a reception circuit 20 and a modulator 21, and demodulated data 12 and a reception level signal 16 are obtained. A modulator 23 reconstitutes a modulated wave 13 from the demodulated data 12, and an amplitude detector 21 detects the amplitude of the modulated wave, thus taking out amplitude level variations of the received wave due to modulation components. An analog subtractor 27 cancels the amplitude level variation component with respect to the reception level signal of the received wave. With the cancellation of the amplitude level variations of the received wave due to modulation components, it is possible to follow up quick amplitude level variation of the received wave.

Received signal strength detecting circuit

In an automatic frequency control device for tuning the frequency of an intermediate frequency (IF) signal to a desired or target frequency, a frequency mixer subtracts the frequency of a received signal coming in through an antenna from the frequency of a local oscillation signal output from a voltage controlled oscillator. A reference oscillator outputs a reference oscillation signal on the basis of a control voltage from a digital/analog converter. The local oscillation signal from the voltage controlled oscillator is synchronous in phase to the reference oscillation signal. A frequency measurement circuit measures the frequency of the IF signal. A subtracter subtracts the frequency of the IF signal from the target frequency and thereby produces a frequency error. A multiplier multiplies the frequency error by, in a proportional relation between the frequency of the IF signal and a voltage represented by a control voltage signal, the reciprocal of a gradient of the voltage of the control voltage signal to the frequency of the IF signal. An adder adds the control voltage signal to the output of the multiplier, thereby correcting the control voltage signal. The digital/analog converter converts the control voltage signal to an analog signal and thereby outputs the control voltage.

Automatic frequency control device for tuning an intermediate frequency

A frequency control circuit for a receiver of phase shift keying (PSK) modulated signals comprises intermediate frequency (IF) signal generation circuit for generating an IF signal from a local oscillation signal. A measurement circuit measures the frequency of the IF signal. A detection circuit detects the frequency shift due to the PSK modulation to output a frequency shift signal in response to a first control signal. A control circuit detects that the frequency of the IF signal is converged until the detection circuit can detect the frequency shift due to the PSK modulation. A frequency control circuit further comprises an arithmetic operation circuit for detecting the frequency of the IF signal which can not be affected by the frequency shift due to the PSK modulation, a local oscillation signal generation circuit for outputting a local oscillation frequency signal in accordance with a second control signal, and a compensation circuit for compensating the second control signal in order to converge the frequency of the IF signal on a desired frequency.

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Tokyo, Japan

Kazuo Ogoro