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

Systems and methods for beamforming in radio frequency identification (RFID) applications are disclosed. A beamforming system uses a distributed architecture and techniques for antenna beamforming using a feedback control loop to direct radio frequency (RF) energy onto a specific region, referred to as an interrogation zone, which includes a calibration node where one or more RFID tags may be located. The distributed architecture of the beamforming system is resistant to fading and shadowing effects, providing accurate RFID reader operation even in environments with multi-path reflections or environmental changes, such as people moving around or changes in the location of equipment.

A high accuracy search and tracking system that uses a round-trip messaging scheme in which the time of arrive (TOA) of ranging signals is accurately determined to yield the range estimates between a target communications device and one or more search communications devices. Successive ranging estimates are used by a search device to home in upon the target device. The physical location pinpoint communications system can be used alone, or in combination with other location estimation systems that can be used initially, or throughout the search and tracking process to pinpoint the physical location of the target device. The search radio(s) transmits ranging signals to the target radio which responds by transmitting reply ranging signals. Upon reception of the reply ranging signal, the search radio determines the range to the reference radio from the signal propagation time. Errors in TOA estimates can be minimized using advanced processing techniques, if required.

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.

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.

In signal detection system and method implemented to reduce the effects of interference in multi-user detection systems, a receiver defines a frame of symbols containing at least one window based upon a number of user signals contained in a received signal r(t). A symbol amplitude of a single-user in the multi-user system is approximated over the window of the frame based on a number of reflected signal paths of the received user signal. A perturbative correction value is calculated based upon a correlation matrix. An estimation of the symbol amplitude of the single-user signal is calculated over one or a number of windows of the frame. The single-user signal is detected when the symbol amplitudes of the entire signal within the frame has been calculated. To reduce the number of interfering users in a multicell CDMA system, the symbol codes are modified to include an even code and an odd code. The even and odd codes are symmetrically separated over the duration of the symbol to form an interference reduction window. If the delay offsets of the symbol codes are less than the interference reduction window and the even codes are assigned to a first cell, and odd codes to adjacent cells, then the adjacent cell interference vanishes.

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 noncontact sleep monitoring device based no ultrawide-band radar and a noncontact sleep staging method based on ultrawide-band radar. The noncontact sleep monitoring device based no ultrawide-band radar comprises an ultrawide-band radar module, a data acquisition and transmission module, a power module, a data cable and an upper computer. The noncontact sleep staging method includes: using the noncontact sleep monitoring device to acquire radar echo data of a human body lying down and transmit the same to the upper computer; allowing the upper computer to perform DC component removal and Fourier transform on the radar echo data, and analyzing and distinguishing body movement states through frequency-domain waveform; subjecting the radar echo data to digital filtering and Fourier transform to extract sign characteristic parameters; staging the sleep states according to the analyzed and extracted body movement states and sign characteristic parameters. The noncontact sleep monitoring device based no ultrawide-band radar and the noncontact sleep staging method based on ultrawide-band radar can acquire body movement and sign information in noncontact and interference-free manner and can stage the sleep condition, and good comfort and convenience of use are provided.

This invention relates to an equalization apparatus and an equalization method. A plurality of equalizers is applied to the equalization apparatus to eliminate interferences of multiple clusters in a channel. The weights of the equalizers are calculated under minimum mean square error criterion by gains of delay paths of multiple clusters in the whole channel. Therefore, the interference of different clusters in the whole channel can be greatly eliminated.

The invention discloses an underwater time service and synchronization method and a system thereof, wherein a server can provide a precise time benchmark, and a user can calibrate a local clock by interacting information with the server, particularly, the method comprises the following steps: when the user needs to calibrate a clock, the user sends an application signal to a server-side with the sending time as the starting point of the time service; when the service-side receives the application signal, the service-side carries out the time-reversal treatment, acquires a response signal and returns the response signal to the user-side, and the service-side further sends the precise sending time of the response signal to the user in an underwater acoustic communication manner; since the time-reversal mirror has the characteristics of temporal and spatial focusing, the response signal can be focused at the user-side; and the user-side carries out the convolution operation on the received signal and the original application signal to obtain a timing signal; accordingly, the finishing point of the time service can be accurately determined by the timing signal, while the sending time of the response signal from the server-side is exactly the center time point of the entire process of the time service. By taking advantages of the very characteristics, the invention can achieve the real-time time service and synchronization.

A wireless communication system that provides energy efficient, high bandwidth and low cost wireless communication. In one embodiment, the communication system utilizes a fan out, pencil beam arrangement in which electro-magnetic energy is transmitted from a hub to customer premises equipment (CPE) with a fan or similar antenna and from the CPEs to the hub via pencil beam antennas. The pencil beam antennas provided higher link margin. The hub may include a shared aperture antenna device for receiving pencil beam transmissions from the CPEs. A shared aperture antenna device may also be used for transmission from the hub to the CPEs.

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.

The invention relates to a maritime ultra-short wave beyond visual range communication device, and belongs to the technical field of the communication device. The device is composed of a radio frequency receiving unit, a radio frequency transmitting unit, a baseband unit and so on. The device is characterized in that an antenna is connected with the radio frequency transmitting unit and the radio frequency receiving unit through an electronic switch. The radio frequency transmitting unit and the radio frequency receiving unit are connected with the baseband unit. The radio frequency transmitting unit is composed of an excitation module and a power module. The radio frequency receiving unit is composed of a radio frequency front end module, a frequency conversion module, an intermediate frequency amplification unit and an intermediate processing module. The baseband unit is composed of a DSP digital signal processing unit, an FPGA field-programmable gate array module. The device has the advantages that the noise coefficient is low, the sensitivity is high, the dynamic range is wide, the low signal to noise ratio demodulation is accurate, the multi-path interference of remote communication can be reduced, the maritime beyond visual range communication distance is long, the communication quality is good, and the existing problems that the multi-path interference of the remote transmission is serious, the noise interference is high, the beyond visual range communication cannot be realized, and the maritime beyond visual range communication quality is influenced are solved.

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.

This invention provides a channel estimation method based on two-dimension spreading spectrum, which contains time domain receiver and frequency domain receiver receiving channel estimation method, using two-dimension spreading spectrum ideal processing one dimension spreading spectrum signal in time domain and frequency domain, fully utilizing the energy of receiving leading signal and reducing multiple route interference, dividing signal band width into many sub-band width less than relative band width to reduce the influence of channel frequency selectivity and raise the accuracy of channel estimation, said invention can be used for ime domain receiver and frequency domain receiver.

The invention relates to a pseudo-range feedback integrated navigation method for reducing multi-path interference, to improve the satellite navigation positioning accuracy. The method is characterized by comprising the following steps: setting a pseudo-range residual rejection threshold, comparing the pseudo-range residual rejection threshold with a pseudo-range residual absolute value of each ofassociated navigation satellites, setting the satellites of which the respective pseudo-range residual absolute value is greater than the pseudo-range residual rejection threshold as the unusable satellites, setting the satellites of which the respective pseudo-range residual absolute value is less than or equal to the pseudo-range residual rejection threshold as the effective satellites, settingmeasured pseudo-range observed quantity of each of the effective satellites as the effective and usable measured pseudo-range observed quantity and participating in subsequent navigation solution, setting measured pseudo-range observed quantity of each of the unusable satellites as the unusable measured pseudo-range observed quantity for rejection, namely the subsequent navigation solution is notparticipated in. Therefore, the influence of the measured pseudo-range observed quantities with too large error generated by multipath interference on the satellite positioning accuracy is reduced oravoided.

The invention discloses a circularly polarized positioning antenna and wearable equipment. The circularly polarized positioning antenna comprises a feed branch knot, a first feed arm and a second feedarm, wherein the first feed arm and the second feed arm form an angle; a first radiation arm is coupled with the first feed arm, the first radiation arm is arranged in a first clearance area extending in the arrangement direction of the first feed arm in a bent mode, and the first clearance area is located on one side of the first feed arm; a second radiation arm is coupled with the second feed arm, and the second radiation arm is arranged in a second clearance area extending along the arrangement direction of the second feed arm in a bending manner; the electric signals on the first radiation arm and the second radiation arm meet the conditions that the amplitudes are equal and the phase difference is 90 degrees, and circular polarization radiation is realized, so that multipath interference is reduced, and the positioning precision of the positioning antenna of the wearable equipment is effectively improved; and the antenna is arranged in the clearance areas in a bending mode, so that the size of the whole antenna can be reduced, miniaturization is facilitated, and the antenna can be achieved on a wearable product more easily.

The invention discloses a real vehicle frequency modulation radio interference test system and method, related to the technical field of vehicle test. The real vehicle frequency modulation radio interference test system is equipped with a portable media device and a FM transmitting circuit and a signal processing and contrast display circuit connected with the portable media device, and is also equipped with a vehicle host connected with the signal processing and contrast display circuit; the FM transmitting circuit is equipped with an FM transmitting antenna; and the vehicle host is equippedwith a radio antenna. According to the real vehicle frequency modulation radio interference test system and method provided by the invention, the initial test signal (1kHz) is compared with the signaloutput by the demodulation of a vehicle computer in real time, and the distortion of the real vehicle output waveform is monitored at any time; once the vehicle computer is interfered by electrical equipment on the vehicle such as a windscreen wiper, the demodulated waveform is distorted, and through performing real-time dual channel visual comparison with the original 1kHz modulation signal, thereal vehicle interference source can be located quickly, and an important basis is provided for the sound evaluation of the real vehicle radio.

The invention discloses a circularly polarized positioning antenna and wearable equipment. The circularly polarized positioning antenna comprises a first annular radiator working in a first frequencyband, a first branch knot which is in coupling connection with the first annular radiator and is used for accessing a first feed signal so as to excite the first annular radiator to work in a first radiation mode, and a second branch knot which is in coupling connection with the first annular radiator; a preset distance is formed between the second branch knot and the first branch knot; the secondbranch knot is used for grounding or used for accessing a second feed signal; the two radiation modes have the same amplitude and 90-degree phase difference, namely the annular radiator generates right-handed circular polarization radiation. Therefore, the positioning antenna can better receive navigation satellite signals, and right-handed circular polarization radiation generated by the annularradiator can also filter left-handed circular polarization navigation satellite signals reflected by a high-rise building or the ground to reduce multipath interference, thereby effectively improvingthe positioning precision of the positioning antenna of the wearable equipment.

The invention relates to the technical field of electronic communication, and provides a positioning antenna and wearable equipment. The positioning antenna comprises an annular radiator which is connected with a coupling body in a coupling manner, and the coupling body extends along the edge of the annular radiator; the positioning antenna further comprises a feed branch knot which is in couplingconnection with the annular radiator; one end, far away from the annular radiator, of the feed branch knot is used for accessing a radio frequency signal; the positioning antenna further comprises agrounding branch knot which is in coupling connection with the annular radiator; one end, far away from the annular radiator, of the grounding branch knot is used for accessing a geoelectric signal; the annular radiator of the positioning antenna can generate right-handed circular polarization radiation, so that the positioning antenna can better receive a navigation satellite signal, and meanwhile, the right-handed circular polarization radiation generated by the annular radiator can also filter the left-handed circular polarization navigation satellite signal reflected by a tall building orthe ground to reduce multipath interference; and the positioning precision of the positioning antenna of the wearable equipment is effectively improved.

A system for reducing multipath interference in a wireless data transmission generally includes a processor and memory device for capturing one or more data packets of the wireless data transmission. The transmitting device associates a time value and/or a spatial value to each of the data packets. Upon capture, the processor determines whether the captured data packet is reflective or non-reflective by comparing the time value or spatial value, as applicable, of the captured data packet to the time value or spatial value of each stored non-reflective packet. The system identifies the captured data packet as non-reflective, if the time value (or spatial value) of the captured packet is different from the time value (or spatial value) of each stored non-reflective packet.

A wireless communicating apparatus is provided which includes two receiving methods, and can determine a favorable receiving method. The wireless communicating apparatus executes, which is provided with the two receiving methods of a first receiving method which is used in a propagation path environment in which it is necessary to reduce the multi-path interference, and a second receiving method which is used in the propagation path environment in which it is not necessary to reduce the multi-path interference, a first determination (step S1) for determining whether or not the fluctuation in time for the path is less than a predetermined threshold, and a second determination (step S2) for determining whether or not the number of the paths is less than a predetermined threshold, and determines (step S3, 4) to use which receiving method of the first receiving method or the second receiving method to communicate via wireless according to a first determination result and a second determination result.