40results about How to "Reduce multipath interference" patented technology

A digital receiver, that may be used to receive VSB / QAM digital television signals, includes an adaptive fine carrier recovery circuit that compensates for deviations in the carrier frequency or phase. The carrier recovery circuit de-rotates a signal including phase errors. Estimations of phase errors are filtered using a filter whose gain and bandwidth are adjusted adaptively. This allows the carrier recovery circuit to track phase / frequency offset without introducing significant jitter. In one embodiment, the receiver includes a DFE, and the adaptive carrier recovery circuit mitigates instability that might be associated with the DFE.

This invention relates to sense through the wall radar. A main channel of a radar system (12) is operated at a frequency capable of penetrating opaque barriers such as the wall (24) of a building (22) to sense targets (16) therein. The main channel performance may be impaired by multipath interference, i.e., radar returns resulting from targets (20) outside the building (22) illuminated by reflection from the wall (24). A guard channel of the radar, operating at a higher frequency which does not penetrate the wall (24), is used to identify targets (20) outside the building (22) and suppress the multipath interference they produce in the main channel.

A frequency-division multiplexing transmission apparatus for transmitting data in a frequency spectrum specific to both symbol and mobile station, is disclosed. The apparatus encodes transmission data, modulates the encoded data, compresses the time domains of each symbol of the modulated transmission-symbol sequence, repeats the symbols a specified number of times, rearranges each of the symbols of the obtained repetitive-symbol sequence so that they have the same arrangement as the transmission-symbol sequence, generates each phase that changes at a speed specific to each symbol of the transmission-symbol sequence, performs phase rotation specific to the symbols for each symbol of the rearranged repetitive-symbol sequence, generates phase that changes at a speed specific to a mobile station, performs phase rotation specific to the mobile station for the symbol sequence for which the phase rotation was performed, and transmits the phase-rotated symbol sequence.

A receiving apparatus, a receiving method, and a radio communications system are disclosed. The receiving apparatus is for receiving CDMA signals transmitted by M antennas and received by N antennas, where M and N are positive integers. The receiving apparatus includes a multipath receiving signal demodulating unit for primary demodulation of the CDMA signals received by the receiving antennas to obtain estimated transmission signals, and for obtaining signals in a multipath environment of each path of the receiving antennas based on the estimated results. Further, the receiving apparatus includes a multipath interference canceling unit for deducting signals of the paths other than a target path from the signals received by the receiving antennas to obtain multipath interference cancelled signals. Further, the receiving apparatus includes a demodulator for secondary demodulation of the multipath interference cancelled signals.

The invention provides a GNSS multipath signal simulating-and-generating method and a GNSS multipath simulating-and-generating system. The GNSS multipath signal simulating-and-generating method comprises the steps of acquiring a GNSS signal of an urban valley region by means of a high-sampling-rate broadband signal sampler and introducing out intermediate-frequency data, and furthermore calibrating acquisition route information by means of high-precision combined navigation calibration equipment; extracting a multipath signal characteristic parameter in the intermediate-frequency data through a multipath estimation algorithm; estimating three parameter models of the GNSS signal in an urban environment according to the multipath signal characteristic parameter, wherein the three parameter models comprises a multipath signal delay distribution probability density model, a multipath signal energy ebb model and a multipath signal life cycle model; generating the characteristic parameter of the simulated multipath signal based on the three parameter models, and transmitting the characteristic parameter of the simulated multipath signal to a navigation signal simulator, thereby generating a corresponding simulated multipath signal. The GNSS multipath signal simulating-and-generating method and the GNSS multipath signal simulating-and-generating system settle a technical problem of incapability of simulating the multipath signal with a reality characteristic.

The embodiment of the invention discloses a system and a method for accurately positioning a wireless sensor network and is applied to the field of communication. The system comprises one or more positioned objects and a server, wherein each positioned object comprises an identification card used for performing information interaction with one or more wireless card readers which are arranged in a wireless card reading base station; respective relative distance relative to each wireless card reader is measured by using a symmetrical double-sided two-way ranging (SDS-TWR) algorithm; and the server is used for calculating and determining a coordinate position of each identification card by using a semidefinite programming algorithm according to the relative distance. Due to the SDS-TWR positioning technology and the semidefinite programming algorithm, the system has the advantages of high stability, high positioning accuracy, high operating rate and high expandability, is applicable to indoor accurate positioning, such as accurate positioning for underground coal mines, prison staff, commercial building personnel and assets and the like, and is also applicable to outdoor positioning, such as positioning in intelligent vehicle management, outdoor security patrol and the like.