Murata Manufacturing Co., Ltd.

Murata Manufacturingco., Ltd.

Tetsu Nishimura

Toru Ishii

Motoi Nakanishi

Nobumitsu Amachi

Ikuo Takakuwa

Suguya Ibaraki

Yuki Maruno

Hisaki Honjo

A target location inference apparatus includes a receiving section and an operation section. The receiving section receives a first radio signal from a first transmitter disposed on a target and a second radio signal from a second transmitter disposed in a reference location. The operation section infers a target presence range in which the target is present with respect to the reference location. The target presence range is inferred based on a first received radio signal strength, in the receiving section, of the first radio signal and a second received radio signal strength, in the receiving section, of the second radio signal.

Target location inference apparatus, target location inference method, target information providing apparatus, and target location inference system

A location estimation system includes non-directional stationary devices having respective non-directional antennas configured to receive a radio signal transmitted by a mobile device; and directional stationary devices having respective directional antennas configured to receive a radio signal transmitted by the mobile device. The non-directional stationary devices output, as pieces of location estimation information for estimating a location of the mobile device, pieces of information indicating received signal strength indicators of the received radio signal. The directional stationary devices output, as pieces of complementary information for identifying a non-directional stationary device used for location estimation from among the non-directional stationary devices, pieces of information indicating received signal strength indicators of the received radio signal.

Location estimation system and location estimation method

A position detection system () includes receivers (to) constituting a radio mesh network, and a gateway device (). Each of the receivers (to) includes a receiving unit (), a sending unit (), and a control unit (). When the receiving unit () in each of the receivers (to) receives the beacon, the control unit () generates first reception information containing information indicating signal strength of the received beacon and identification information of the relevant receiver, and sends the first reception information from the sending unit (). When the receiving unit () receives second reception information, the control unit () sends the second reception information. When receiving the second reception information generated by the other receiver, the receiver () connected to the gateway device () sends the received second reception information to the server device () through the gateway device ().

Position detection system and receiver

A position estimation apparatus includes receivers that are disposed at different known positions and are configured to measure a reception intensity of a radio wave emitted from a mobile object and a calculator configured to sequentially perform, for each target receiver that is one of the receivers, processing for updating an estimated position of the mobile object such that the estimated position is closer to a presence circle having a center at the target receiver and a radius based on a reception intensity measured by the target receiver.

Position estimation apparatus and position estimation method

A lighting system serving as a wireless network system includes a plurality of lighting appliances, which are a plurality of wireless devices, that each have unique identifier and transmit/receive a radio signal. Under control performed by a lighting controller, an operation is sequentially performed with respect to each of the plurality of lighting appliances in which one lighting appliance from among the plurality of lighting appliances broadcasts a measurement signal that includes the identifier of that lighting appliance and the other lighting appliances receive the measurement signal and measure reception quality, which depends on the distance between the lighting appliances.

Wireless network system and reception quality measurement method

A position detection system includes a transmitter that transmits a first beacon signal with a first strength and at a first incidence and that transmits a second beacon signal with a second strength, which is greater than the first strength, and at a second incidence, which is lower than the first incidence, a plurality of receivers that are installed at known positions different from each other and that measure signal strengths of the first beacon signal and the second beacon signal, and a calculator that performs first processing in which the position of the transmitter is detected on the basis of a signal strength of the first beacon signal measured by one of the receivers and second processing in which the position of the transmitter is detected on the basis of signal strengths of the second beacon signal measured by two or more of the receivers.

Position detection system

A radar device includes a transmission antenna and a reception antenna having a plurality of antenna elements. The radar device switches the antenna elements in synchronization with a modulation cycle, thereby obtaining a reception signal. At this time, the radar device obtains the reception signal by switching the antenna elements using a first measurement phase and a second measurement phase having different switching cycles as one set. The radar device calculates an azimuth sine value sin &#x3b8;from the reception signal in the first measurement phase and also calculates an azimuth sinusoidal value sin &#x3b8;from the reception signal in the second measurement phase. Then, the radar device calculates a relative velocity V from the azimuth sine value sin &#x3b8;, the azimuth sine value sin &#x3b8;, an interval time difference &#x394;t between switching cycles, and an inter-antenna element spacing d.

Target detection method for use in radar and radar device using the target detection method

A radar apparatus includes a transmitting antenna and a receiving antenna that has a plurality of antenna elements, and switches the plurality of antenna elements in synchronization with a modulation period to acquire receiving signals. At this time, the antenna elements are switched in accordance with a combination of a first sub-phase and a second sub-phase in which the antenna elements are sequentially switched in opposite directions to thereby acquire the receiving signals. The radar apparatus calculates an azimuth sine value sin &#x3b8;from the acquired receiving signals of the first sub-phase and calculates an azimuth sine value sin &#x3b8;from the receiving signals of the second sub-phase. Next, the radar apparatus calculates an actual azimuth &#x3b8; through an averaging process of these azimuth sine values sin &#x3b8;and sin &#x3b8;.

Radar target detecting method, and apparatus using the target detecting method

A radar target detection method in which an azimuth at which a target is located is detected on the basis of reception signals obtained through antenna elements of an array antenna by detecting a change in levels of spectrum peaks in an azimuth spectrum of reception signal intensities, calculating a level of correlation between the level change of each spectrum peak and a directivity pattern of the array antenna in an azimuth range corresponding to the spectrum peak, and determining an azimuth corresponding to one of the spectrum peaks having the highest corresponding correlation level to be the azimuth at which the target is located.

Radar target detection method and radar apparatus using the same

A radar system in which a beat signal is generated by transmitting a transmission signal that is subjected to frequency modulation into a triangular wave and receiving a reflection signal from a target, the beat signal is sampled, and a window function is applied to yield a discrete frequency spectrum. When the window function is applied, a first window function having an amplitude that is gently attenuated from the center of the sampling period toward both sides thereof is applied in a lower frequency band in the frequency spectrum (at close range), and a second window function having an amplitude that is sharply attenuated from the center of the sampling period toward both sides thereof is applied in a higher frequency band in the frequency spectrum (at far range).

Radar system with peak frequency analysis and window functions

A radar can detect target azimuths located outside and adjacent to a scanning angular range of a beam by determining changes in received signal strength (a signal-strength profile) in the azimuthal direction as a function of a beam azimuth in a predetermined scanning angular range, and estimating the target azimuth causing the signal-strength profile from the signal-strength profile, which is portion of a convex located adjacent to the outermost angle in the scanning angular range. For example, the target azimuth is estimated by a ratio between the received signal strength at the outermost angle of about 10.0&#xb0; and the received signal strength at about 9.5&#xb0;, which is one beam inside the outermost position.

Radar

An FM-CW radar detects at least one of the relative distance and the relative speed of a predetermined object based on the frequencies of projection portions observed in the frequency spectrums of beat signals in an ascending-modulation section and a descending-modulation section, where the projection portions are generated by one and the same object. The radar determines the moving speed of a predetermined moving object such as a vehicle or the like having the radar mounted thereon, and the frequency difference between the projection portions observed in the frequency spectrums of the beat signals in the ascending-modulation section and the descending-modulation section is inversely calculated, where the frequency difference corresponds to the stationary object, and a predetermined pair corresponding to the frequency difference is extracted on a priority basis.

A radar performs accurate and appropriate pairing even if peaks of approximately identical signal intensities or even if a plurality of peak groups having identical representative beam bearings exist in the frequency spectrum. First, the peak frequency of a peak which appears in the frequency spectrum is determined for each of an up-modulating interval and a down-modulating interval in predetermined beam bearings, and signal-intensity profiles in the beam bearings are extracted with regard to a plurality of beam portions which are adjacent to the beam bearings. Next, the correlation level between the signal-intensity profiles at the up-modulating interval and the down-modulating interval is determined, and pairing is performed in sequence starting from the profiles having a higher correlation level.

A radar system achieves adjustment of a time-change characteristic of a frequency-modulating voltage signal to a voltage-controlled oscillator for determining a transmitting signal such that the time-change characteristic of the frequency-modulating voltage signal is changed by a minute amount and the frequency spectrum of a beat signal is determined. The adjustment is performed so that the shape of a bulge in signal intensity included in the frequency spectrum is the sharpest.

Radar system

In a radar, a coupler extracts a part of a transmission signal as a local signal and a mixer mixes a reception signal from a circulator and the local signal so as to output an intermediate frequency signal which is the frequency difference between the transmission signal and the reception signal. An IF-amplifying circuit amplifies the intermediate frequency signal and an AD converter converts the signal to digital data. A DC-removing unit removes a DC component by subtracting the average from the data and an FFT operation unit performs fast Fourier transform so that the distance to a target and the relative velocity of the target are calculated based on a peak included in the frequency spectrum.

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Toyonaka, Japan

Tetsu Nishimura