Nippon Telegraph and Telephone Corporation

Nippon Telephone and Telegraph Corporation

Mamoru Ugajin

Tsuneo Tsukahara

Kenji Suzuki

The transmitting side encodes a digital signal to be transmitted by using a code not containing any DC component, and transmits the digital signal without using any carrier. The receiving side performs decoding corresponding to encoding for the received signal, and restores the original digital signal.

Wireless communication system, wireless transmitter, wireless receiver, wireless communication method, wireless transmission method and wireless reception method

A spread-spectrum demodulator includes a spreading code generating section, correlation value computing section, data signal demodulating section, peak signal detecting section, and spreading code generation control section. The spreading code generating section generates a spreading code for correlating with a received spread signal. The correlation value computing section computes a correlation value between the spread signal and the spreading code output from the spreading code generating section. The data signal demodulating section detects the peak of an output from the correlation value computing section and demodulates a data signal on the basis of the detected peak. The peak signal detecting section detects the peak of the output from the correlation value computing section. The spreading code generation control section changes the shifting direction of the spreading code relative to the spread signal every time a peak is detected by the peak signal detecting section.

Spread-spectrum demodulator

A mixer circuit used in a radio receiver for mixing two frequencies and providing an intermediate frequency which is the difference of the two frequencies. Excellent image rejection is provided by decreasing an amplitude error and a phase error of an output IF signal in differential form.

Mixer circuit

An input stage for adjusting the gain or conductance Gm depending upon a control voltage applied and an output stage for securing a sufficiently high output impedance and a sufficiently wide output dynamic range are connected between the voltage source and the ground in parallel with each other.

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Tokyo, Japan

Mamoru Ugajin