Kabushiki Kaisha Toshiba

Kabushiki Kaisha Kaisha

Seiji Isobe

Takeshi Sawada

Masaru Suga

Seiji Okubo

Takao Hirakura

Makoto Kaijima

A nonlinear compensator comprising a signal processing section, a distortion detecting section, and a distortion correcting section. The signal processing section detects the time difference and phase difference between two signals by calculating correlation, synchronizes the two signals with each other, and causes the phase of one signal to coincide with that of the other. The distortion detecting section determines an amplitude error and a phase error in the two signals and inputs the errors as distortion components to a distortion correcting section. The distortion correcting section sequentially selects the amplitude, the phase, and the amount of compensation corresponding to the value of the amplitude from the amounts of compensation registered at the initial stage and updated adaptively, and adds the amount of compensation to the digital base band signal obtained at the input demodulation section to compensate for the distortion components.

Nonlinear compensator

An OFDM modulator includes an OFDM modulator section for conducting OFDM modulation on a signal, based upon an OFDM clock F , and outputting an OFDM signal, an adder for adding the OFDM clock F to a local signal F for frequency conversion, and a frequency converter for conducting frequency conversion on the OFDM signal supplied from the OFDM modulator section, based upon an output signal of the adder. The OFDM modulator thus outputs an IF signal having a frequency equivalent to that of the local signal. As a result, the floating frequency component of the OFDM clock on the OFDM modulator section side is canceled by the floating frequency component of the OFDM clock on the frequency adder side. There is thus obtained an IF signal which can be synchronized to a frequency (for example, 10 MHz) of an external device and which has the same frequency as that of the local signal F .

Signal generator and OFDM modulator synchronized to external device

A phase shifter includes first and second mixers which mix a first signal with a second signal having a phase different from the first signal, respectively, third and fourth mixers which mix the second signal with the output signals of the first and second mixers and a combiner which combines the output signals of the third and fourth mixers to produce an output signal having a phase which is inverted with respect to the first signal.

Phase shifter

An interference signal suppressor includes two antennas for receiving desired signals and interference signals, a first adder circuit in which the output signals of two antennas are added to each other, a subtractor circuit in which the output signal of two antennas are subtracted to each other, a signal generating circuit for producing an opposite phase signal with that of the interference signal provided from the first adder circuit and the opposite phase signal are added to each other and a controlling circuit for adjusting the amplitude and the phase of the opposite phase signal to suppress the interference signal.

Growing community of inventors

Yokohama, Japan

Seiji Isobe