Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporaiton

Seiji Okubo

Toshiharu Kojima

Akinori Fujimura

Tatsuya Uchiki

Hiroyasu Sano

Makoto Miyake

Taisei Suemitsu

Takashi Asahara

Akinori Fujimora

Kentaro Gotou

A wireless apparatus which performs a frequency conversion on a received signal with a mixer and an analog filter, and which corrects for distortion of the received signal, which occurs because the analog filter is not an ideal one, using a digital filter disables the filtering of the received signal by the digital filter when determining from the reception power level (or reception amplitude level) of the received signal that the filtering of the received signal by the digital filter will increase the distortion of the received signal.

Wireless apparatus

A spread spectrum transmitter provides delays having different magnitudes to spread spectrum (SS) signals for a plurality of channels, and multiplexes the SS signals to generate transmission multiplex SS signal. A spread spectrum receiver calculates a partial correlation value between the transmission multiplex SS signal and spreading codes multiplied to the SS signals, multiplies the partial correlation values by a prescribed matrix prepared based on each orthogonal code sequence to calculate a plurality of orthogonal correlation values. The receiver identifies for a respective channel each parallel data sequence related in advance to an orthogonal code sequence whose orthogonal correlation value is a maximum, corrects delay differences of the parallel data sequences, and then performs sampling and parallel-serial conversion to obtain a serial demodulated data sequence.

Spread spectrum transmitter and spread spectrum receiver

A spread spectrum transmission apparatus includes, a chip clock generation section which outputs a chip clock in one frame formed of M+L&#x2212;1 chips, a frame clock generation section which outputs a frame clock synchronized to frame occurrence timing, SS-PPM signal generation sections each of which inserts a pseudonoise code sequence corresponding to one period from some of M chips located at a head of a frame based on K-bit transmission data and generates an SS-PPM signal, delay sections which respectively delay N SS-PPM signals respectively by determined delay quantities, and a multiplexing section which adds up all of outputs respectively of the delay units and generates a multiplexed SS-PPM signal.

Spread spectrum transmission apparatus, spread spectrum reception apparatus, and spread spectrum communication system

A base band signal is sampled, based on an asynchronous sampling clocking, to output two sampled data series. A transmission side complex symbol frequency generator generates a complex transmission symbol frequency component combining an envelope value and an amplitude change amount value, which are each calculated from the two sampled data series. The transmission side complex symbol frequency component is provided to a correlation value calculator that outputs a correlation data series correlated to the complex symbol frequency and the symbol frequency generated by a cosine wave generator. The correlation data series is converted a timing error by an inverse tangent calculator. By the above configuration, a timing reproducing unit, which includes the above components, determines the timing error at a sampling speed of twice the symbol rate.

Method and apparatus for reproducing timing, and a demodulating apparatus that uses the method and apparatus for reproducing timing

There are provided a spread code generating section generates a spread code list from the input parallel information, spread modulating sections generate a plurality of parallel spectrum spread signals corresponding to the parallel information list by multiplying each of the parallel information list and the spread code list respectively, phase shifting sections shift the phase of the parallel spectrum spread signals, delay sections delay the parallel spectrum spread signals. A multiplexing section generates a multiplexed spectrum spread signal by adding the delayed parallel spectrum spread signals. The multiplexed spectrum spread signal are converted into a radio frequency signal, amplified and then transmitted.

Spread spectrum communication system and method for the same

In-phase and orthogonal components of a base band signal having a preamble symbol are squared to obtain squared in-phase orthogonal components. Amount of correlation is obtained between the squared in-phase component and a symbol frequency component output from a VCO or an oscillator, and amount of correlation is obtained between the squared orthogonal component and the symbol frequency component. Finally, a phase control signal for carrying out a phase control is generated by using the obtained amount of correlations.

Timing reproducing device and demodulator

A timing recovery device and demodulator. An adding device adds together an in-phase component and a quadrature component of a base band signal. A subtracting device subtracts the in-phase component and the quadrature component of the base band signal from each other. Then, the correlation between the added signal and a &frac12; symbol frequency component generated at the receiver side and the correlation between the subtracted value and the &frac12; symbol frequency component are calculated. A vector selector compares the added value correlation signal and the subtracted value correlation signal, and selects the larger one of the correlation signals. A timing phase difference calculator then calculates a timing phase difference, using the vector angle indicated by the selected correlation signal.

Timing reproducer and demodulator comprising this

In a DLL, in-phase correlation signal and orthogonal correlation signal are squared and adder to generate correlation power. Delays are provided so that the peaks of N number of divided correlation power portions to have coincided timing with each other. Composite correlation power is generated from the respective correlation power portions. A composite error signal of a sample clock is generated by subtracting the composite correlation power from the composite correlation power that has been delayed. A data clock is generated by frequency-dividing the sample clock based upon an acquisition pulse. A sample clock is finally generated based upon the composite error signal that has been latched and noise-removed therefrom in synchronized timing with the data clock that has been delayed.

Delay lock loop, receiver, and spectrum spreading communication system

In a communication system using the time diversity transmission scheme, the communication system provided with the stable automatic frequency control circuit with the wide frequency pull-in range and under low CN ratio transmission is achieved by removing the modulation phase from the received data through the application of the data correlation of the time diversity. The frequency offset in the received signal is compensated as the phase rotator rotates the phase of the received signal, the phase converter converts the phase rotator output into a phase, the serial-to-parallel converter converts the phase converter outputs into serial-to-parallel sequence, the delay units gives a delay to the serial-to-parallel converter output, the phase adder adds the serial-to-parallel converter output to the delay unit output, the multiplier multiplies the phase adder output by a certain value, the integrator integrates the multiplier output, another integrator integrates the integrator output, and the phase rotator controls the phase of the received signal based on the other integrator output.

Automatic frequency control communication system

In the identical spread code multiplex SS system, a delay correction unit and a multiplexer calculates the multiplexed square correlation value by matching the peak values and adding the square correlation values of all the multiplexed signals. The multiplexed signals are the signals obtained by multiplexing an RF signal in such manner that different specific delay times are respectively given to parallel transmission information sequences multiplied by identical spread codes. Therefore, code synchronization can be realized by using only one correlator for both the orthogonal and an in-phase components.

Initial acquisition circuit

A demodulator is made compact, and with a simple circuit arrangement, and also having a better bit error rate characteristic. A timing phase synchronization detecting circuit 219 judges any one of the following two conditions based upon baseband phase data 202, i.e., an UNLOCK (timing phase asynchronous) condition, and a LOCK (timing phase synchronous) condition. Based upon the judgement result of the timing phase synchronization detecting circuit 219, in a timing recovering means 221, a frequency range of a PLL (phase synchronization loop) is variable, whereas the number of data entered within 1 symbol time is variable in a frequency synchronizing means 222 and a carrier recovering means 223. A data demodulating means 224 outputs demodulation data 206 in response to baseband phase data 202 and a recovery carrier signal 205.

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Tokyo, Japan

Seiji Okubo