Abstract: A wireless communication apparatus has a first communication unit configured to perform at least one of transmission and reception by using a multicarrier signal constituted by a plurality of subcarriers shaped by a band-limited pulse waveform; and second communication unit configured to perform at least one of transmission and reception by using a signal having a different modulation format or modulation constant from said signal of said first communication unit. Said first communication unit configured to perform communication without using at least one of said plurality of subcarriers, and said second communication unit configured to perform communication using a band of said subcarrier not used by said first communication unit.

Abstract: A receiver includes an array antenna, terminals, switches, a receiving circuit, a switch control unit and a reactance setting unit. Receiving circuit determines a received frequency and a received signal quality of a received signal by demodulating the received signal provided from the array antenna. The receiving circuit provides the received frequency to the reactance setting unit as a frequency setting signal, and provide the received signal quality to the switch control unit and the reactance setting unit. The reactance setting unit sets a set of the reactances corresponding to the received frequency in the terminals for each frequency, and the switch control unit switches connections in the switches to provide the received signal quality equal to or greater than the threshold.

Abstract: An array antenna apparatus (100) includes a radiating element (A0) for receiving a transmitted radio signal, two parasitic elements (A1, A2), and two variable reactance elements (12-1, 12-2) connected to the respective parasitic elements (A1, A2), and a directivity characteristic of the array antenna apparatus is changed by changing reactances set to the variable reactance elements. An antenna controller (10) selects and sets one reactance to be set from those in a first case in which a first reactance set is set to the two variable reactance elements (12-1, 12-2) and a second case in which a second reactance set is set to the two variable reactance elements (12-1, 12-2) to be able to obtain a diversity gain equal to or larger than a predetermined value, based on a received radio signal, based on signal quality of the radio signal.

Abstract: An antenna structure with reduced bulkiness and capable of changing antenna directivity is provided. In order to achieve such an effect, the antenna structure includes a feed element of one of an inverted F type and a loop type, and a passive element of one of the inverted F type and loop type, and having a variable reactor so as to be capable of changing an electrical length, and the feed element and passive element are disposed with a predetermined distance therebetween.

Abstract: An array antenna apparatus includes a dielectric substrate, a feeder element, a parasitic element, and a directivity control unit. The feeder element and the parasitic element have an equal length. The feeder element and the parasitic element are arranged such that they intersect with each other at a substantially central portion of the parasitic element and a feeder unit of the feeder element and such that the parasitic elements are arranged symmetrically around the feeder element. An interval between the feeder element and the parasitic element is not larger than half wavelength of a radio wave. The parasitic element has a varactor diode serving as a variable capacitance element loaded. The directivity control unit supplies a control voltage to the varactor diode, and switches directivity of the array antenna apparatus.

Abstract: An antenna structure with reduced bulkiness and capable of changing antenna directivity is provided. In order to achieve such an effect, the antenna structure includes a feed element of one of an inverted F type and a loop type, and a passive element of one of the inverted F type and loop type, and having a variable reactor so as to be capable of changing an electrical length, and the feed element and passive element are disposed with a predetermined distance therebetween.

Abstract: An array antenna apparatus includes a dielectric substrate, a feeder element, a parasitic element, and a directivity control unit. The feeder element and the parasitic element have an equal length. The feeder element and the parasitic element are arranged such that they intersect with each other at a substantially central portion of the parasitic element and a feeder unit of the feeder element and such that the parasitic elements are arranged symmetrically around the feeder element. An interval between the feeder element and the parasitic element is not larger than half wavelength of a radio wave. The parasitic element has a varactor diode serving as a variable capacitance element loaded. The directivity control unit supplies a control voltage to the varactor diode, and switches directivity of the array antenna apparatus.

Abstract: A receiver includes an array antenna, terminals, switches, a receiving circuit, a switch control unit and a reactance setting unit. Receiving circuit determines a received frequency and a received signal quality of a received signal by demodulating the received signal provided from the array antenna. The receiving circuit provides the received frequency to the reactance setting unit as a frequency setting signal, and provide the received signal quality to the switch control unit and the reactance setting unit. The reactance setting unit sets a set of the reactances corresponding to the received frequency in the terminals for each frequency, and the switch control unit switches connections in the switches to provide the received signal quality equal to or greater than the threshold.

Abstract: A diversity receiver with simplified construction, excellent receiving signal quality even with very low fading speeds wherein, on the basis of a signal from a receiving unit capable of detecting the receiving signal intensity, an antenna changeover is effected when the receiving signal intensity falls below a changeover threshold value. When, at the termination of a first lapse time from the first antenna changeover, the receiving signal intensity is below that immediately before the first antenna changeover, an antenna changeover is again effected and any antenna changeover is prevented from being effected for a second lapse time from the second changeover. The second lapse time is set to be longer than the first lapse time.

Abstract: The invention aims at adaptive array diversity reception of high convergence speed of combined weight by a simple signal processing, in a receiver by time division transmission system. Signals received by antennas (branches) are converted into base band signals in a receiving circuit, and are combined by a complex multiplying section and complex adder. The weight of the complex multiplying section is calculated by a weight calculating section. In the weight update algorithm of the weight calculating section, the step size in the least mean square is variable. That is, the initial value is set at a large value, and is decreased according to the lapse of time in each time slot, and is initialized at every change of time slot. As a result, by the same amount of calculation as in ordinary least mean square, the convergence speed of weight updating can be enhanced.

Abstract: In a diversity receiver, an averaging circuit produces a short-time average value of an instantaneous value of a receiving electric field intensity at a receiving section. A ROM produces an appropriate threshold value corresponding to the short-time average value from the averaging circuit. A threshold decision circuit compares the threshold value produced from the ROM with the instantaneous value of the receiving electric field intensity and controls an antenna switch to switch antennas when the instantaneous value decreases below the threshold value.

Abstract: A frequency modulator includes a reference frequency oscillator, a voltage controlled oscillator provided with a control input terminal and a modulation input terminal, a frequency divider for dividing an output of the voltage controlled oscillator, a phase comparator for generating an output signal corresponding to a phase difference between an output of the reference frequency oscillator and an output of the divider, a first filter having an input terminal and an output terminal, the input terminal thereof being connected to an output terminal of the phase comparator, while the output terminal thereof being connected to the control input terminal of the voltage controlled oscillator, and a second filter having an input terminal and an output terminal, the input terminal being inputted a modulating signal and the output terminal being connected to the modulation input terminal of the voltage controlled oscillator.

Abstract: An optical disk apparatus equipped with an objective lens for converging light from a light source onto a track formed on an optical disk, the objective lens being arranged to be movable and an error detecting section for detecting a difference in position between the light converged by the objective lens and the track on the optical disk. Included in the servo section of the optical disk apparatus are an amplifier for amplifying an output of the error detecting section with an amplification factor which is variable and a filter circuit for cutting off a frequency component of an output of the amplifying means, the cutoff frequency being variable. On the basis of the output of the filter circuit, a moving device moves the objective lens so that the difference between the converged light and said track is reduced. The amplification factor of the amplifier and the cutoff frequency of the filter circuit are determined in correspondence with the position of the objective lens.