102results about How to "Improve the receiving signal-to-noise ratio" patented technology

The invention discloses a synchronous realizing method in the orthogonal frequency-division multiplying system, which comprises the following steps: constructing front/synchronous sequence at the transmitting end to frame and transmit; combining the CP information to do one-time synchronization; utilizing front symbol to estimate the integral times and decimal time-domain frequency deviation; compensating the frequency deviation; using front symbol to do secondary time synchronization; proceeding disposal after synchronizing. The invention improves the synchronous precision to modify the system property as well as the received signal-to-noise ratio, which reduces the calculating quantity without adding the burden of system.

The present invention relates to use of a smart antenna for a RF reader on a Radio Frequency Identification (RFID) system to significantly increase the operating range of the RFID system. The smart antenna can be an adaptive antenna array. The smart antenna comprises a plurality of antenna elements and, by combining the signals from multiple antenna elements, significantly increases the received signal-to-noise ratio. In a noise limited environment, combining the signals to maximize the received signal-to-noise ratio can be based on the maximal ratio combining (MRC) principle. To achieve the best signal quality, the received signal from each antenna can be phase-shifted such that the resultant signals from all antennas are in phase. In addition, the signal from each antenna can be scaled in amplitude based on the square root of its received signal-to-noise ratio.

The method includes following steps: constructing leading / synchronizing sequence on each transmission antenna, as well as carrying out framing and sending operations; carrying out once time synchronization by combining with cycling prefix information on each receiving antenna; using the leading symbols to carry out frequency deviation estimation (FDE) in time domain in integral multiple and decimal multiple for each receiving antenna; merging in equal gain for value of FDE on each receiving antenna so as to obtain final average value of FDE, and carrying out compensation of FDE for data of each receiving antenna; using leading symbol to carry out second synchronization for time; selecting best point of second synchronization for time; using the obtained best point to carry out synchronous post-processing. Satisfying precision required by operation, the invention raises SNR for received signal, does not use too much system resources, and increase redundancy of system, etc.

The invention provides a random access method based on a difference beam, base station equipment and user equipment. The random access method based on the difference beam comprises the following steps: receiving a leading sequence from first UE (User Equipment) by the base station equipment through a difference beam receiving mode; based on the leading sequence, determining an angle deviation of a base station in a beam direction; and performing base station beam adjustment according to the angle deviation of the base station in the beam direction, and transmitting a random access response signal to the first UE through the adjusted base station beam. The random access method based on the difference beam provided by the invention detects the angle deviation of the base station in the beam direction through the difference beam receiving mode, which can adjust a receiving beam of the base station to an optimal beam more quickly than a beam polling mode in the prior art, thereby improving the performance of a random access process.

The invention discloses a Fresnel telescope imaging laser radar, which comprises a laser, a transmitting polarization beam splitter, a first channel space phase modulator, a second channel space phase modulator, a transmitting polarization beam combiner, a laser amplifier, a transmitter-telescope, an optical beam scanner, a receiver-telescope, a receiving polarization beam splitter, a 2*4 90-degree space optical hybrid, an A-path balanced receiver and an A-path amplification and analog to digital converter, a B-path balanced receiver and a B-path amplification and analog to digital converter, a pluralizing device, a time and space coordinate converter, a resampling interpolation space coordinate converter, a matching filter and a control computer. The Fresnel telescope imaging laser radar can realize two-dimensional imaging of a target in a super optical resolution limit, improves the receiving sensitivity and imaging signal-to-noise ratio, greatly increases receiving optical aperture and reduces laser transmitting power. The optical mechanical structures and electronic equipment are simple, and the Fresnel telescope imaging laser radar is a high-resolution imaging laser radar capable of overcoming influence of atmospheric turbulence.

The invention provides a telescope array optical signal reception method based on self-adaptation control of amplitudes and phases. The method comprises the following steps of A, realizing multi-element array reception on optical signals by a telescope array; B, amplifying and filtering the optical signals coming out of each telescope channel successively; C, controlling phase shifters by the feedback of the output end of a superposition output unit to realize the self-adaptation control on the phases, and controlling amplification factors of amplifiers by the feedback of output ends of the amplifiers to realize the self-adaptation control on the amplitudes; and D, enabling the optical signals of all the channels to enter the superposition output unit for coherent superposition after the self-adaptation control of the phases and the self-adaptation control of the amplitudes are performed on the optical signals to obtain high-sensitivity output signals. The invention also provides a telescope array optical signal reception device based on the self-adaptation control of the amplitudes and the phases. The telescope array optical signal reception method and the telescope array optical signal reception device based on the self-adaptation control of the amplitudes and the phases provided by the invention have the beneficial effect that high-sensitivity and high-signal to noise ratio reception is realized on wireless optical signals under the conditions of strong background interference and weak optical signals.

The invention relates to a remote steady communication method for an underwater unmanned platform. By use of the physical characteristic that an underwater acoustic channel is asymmetric about time and by use of a bidirectional adaptive multichannel decision feedback equalizer formed by combining a time reverser and an adaptive multichannel decision feedback equalizer, equalization of a single vector hydrophone-based bidirectional adaptive multichannel decision feedback equalizer is carried out. The remote steady communication method for the underwater unmanned platform introduces an error feedback filter circuit to form the bidirectional adaptive multichannel decision feedback equalizer, so as to carry out the equalization of the single vector hydrophone-based bidirectional adaptive multichannel decision feedback equalizer. According to the remote steady communication method for the underwater unmanned platform, the probability of a signal decision mistake is reduced, and the equalization error rate is further reduced; an error in the past time is fed back into the equalizer to reduce the relevancy between error signals in the equalizer, so that the error rate after the equalization is further reduced, and the steadiness of a receiver is effectively improved; and the equalization performance of the receiver is further improved.

The invention belongs to the technical field of mobile communication, in particular to a multicast transmit beamforming method and system based on angle information. In the invention, the angle information of target mobile stations is utilized to replace the complete channel information used in the traditional beamforming algorithm, thus the method and system are more suitable for a trunking communication system unable to obtain the channel information timely; and the beamforming gain is also utilized to replace the signal to noise ratio (SNR) used in the traditional beamforming algorithm to serve as the new beamforming optimization target, so the specific channel information can not be involved. The flow related to the invention comprises the following three steps: firstly, obtaining the angle information of the mobile stations by a base station; secondly, generating a beamforming vector based on that the beamforming gain serves as the optimization target; and finally, combining the beamforming vector with the signal to finish transmitting. According the invention, the received SNRs of the target users in the group sending services in trunking communication can be obviously improved; and the method and system provided by the invention are very applicable to the trunking communication system.

The invention belongs to the technical field of FM signal processing, and discloses an earphone circuit and a method for processing FM frequency band signals received by an earphone. The method comprises the following steps of: performing low impedance processing on an FM frequency band noise signal coupled to an audio signal through a first capacitor; continuing to perform attenuation processing on the FM frequency band noise signal through magnetic beads to make the energy of the FM frequency band noise signal further reduced; and coupling the FM frequency band signals of a left channel and a right channel of the earphone through a second capacitor to make the strength of the FM frequency band signals increased. The method can inhibit the FM frequency band noise signal in a listening end system from transmitting outwards and enhance the receiving strength of useful FM frequency band signals, thereby effectively improving FM receiving signal-to-noise ratio.

A multipath signal carrier phase error estimation device is used to realize the coherent demodulation of down rake receiver. The expressions of the multipath received signal carrier wave and the local carrier phase error theta can be exported according to the expression of multipath received signal and the following instruction book provides the exporting process; the multipath signal carrier phase error estimation device is provided according to the expressions. The device separately sends the outputs of QAM coherent demodulator to six multiplier units of In-phase and Quadrature, the outputs of three multiplier units of In-phase are sent to three processors and then sent to the other three multiplier units to be multiplied by the three outputs of three multiplier units of Quadrature, and finally the phase error tracking signal of signal in each path can be obtained; the phase error tracking signal control phase shifter adjusts the phase of local coherent carriers and recovers the local coherent carriers which are separately synchronous with three-path received signal carriers, the local coherent carriers are used to demodulate three-path signals and finally the In-phase and Quadrature of the three-path signals are separately combined and descrambled.

The invention relates to a submersible buoy seismic data acquisition station which solves the problem of difficult marine seismic signal acquisition of the existing technology, and is composed of a hydrophone, a buoy, a connecting rod, a digital unit, a control module, a data communication unit, GPS and a power supply module. The buoy floats on the water surface. The hydrophone is placed underwater. The hydrophone and the buoy are connected through the connecting rod L. The digital unit, the control module, the data communication unit, the GPS and the power supply module are arranged in the buoy. The power supply module powers the digital unit, the control module, the data communication unit and the GPS. The control module establishes communication connection with an external host through the data communication unit, and receives an instruction of the external host or a preset instruction to control the digital unit, the data communication unit WU, the GPS and the power supply module. The data communication unit provides a communication service for the acquisition station. The digital unit converts an analog signal of the hydrophone into a digital signal. The GPS unit provides location information and a time marker for the acquisition station. The submersible buoy seismic data acquisition station has the advantages of good stability and noise reducing, and is conducive to improving the seismic signal receiving sensitivity and the signal to noise ratio.

The invention provides a beam forming method for a three-hop relay collaborative communication model. Under the condition that the total power of a relay node is strived not to exceed a certain threshold value, the received signal-to-noise ratio of a destination node is maximum. Two relay node groups exist in the three-hop relay collaborative communication, and each group corresponds to respective beam forming weight vectors. The beam forming method alternately fixes two relay node group weight vectors, applies semi-definite relaxation to convert the original problem into a convex optimization problem, then applies methods, like an interior point method, passes through a plurality of iterations, and finally achieves joint optimization of two weight vectors.

The invention discloses a follow-up tracking WIFI transmission device and a control method thereof. The device includes a cloud deck controller, and an acceleration sensor, a geomagnetic sensor, a Beidou navigation receiver, a wireless communication unit, a WIFI unit and an antenna cloud deck connected to the cloud deck controller. The device also includes a directional antenna arranged on the antenna cloud deck. The directional antenna is connected to the WIFI unit. The control method includes determining the coordinates of the device itself through Beidou satellite signals and sending the coordinate information to other access points; determining an optimal communication chain according to the combination of a routing algorithm and the coordinate information of the whole communication access point combined; determining the posture information of the device itself through the geomagnetic sensor; calculating the antenna azimuth angle and controlling the antenna cloud deck for antenna alignment. According to the invention, long range WIFI communication is realized and a problem of dynamic moving network construction of multiple access points when using the directional antenna is solved. Effects in aspects of prolonging WIFI communication distance, improving communication security, improving network invulnerability, reducing electromagnetic interference and the like are obvious.

Transmitting apparatus and receiving apparatus for communication systems using coded orthogonal frequency-division multiplexed (COFDM) dual-subcarrier modulation (DCM) signals. The same coded data is mapped both to COFDM subcarriers located in the lower-frequency half spectrum of the DCM signal and to COFDM subcarriers located in its upper-frequency half spectrum. The mapping of COFDM subcarriers in those half spectra employ labeling diversity. A primary design goal in some preferred labeling diversity formats is to support reception of DCM with less error when accompanied by interfering additive white Gaussian noise (AWGN). A primary design goal in some preferred labeling diversity formats is to reduce the peak-to-average power ratio (PAPR) of the COFDM DCM signals. In preferred forms of COFDM DCM signal, the quadrature amplitude modulation (QAM) of COFDM subcarriers is Gray mapped to position palindromic lattice-point labels along one of the diagonals of each square QAM constellation.

The invention provides an optical antenna integrating polarization, isolation, receiving and transmitting. A laser beam of a laser emission module passes a wave plate group formed by a lambda/4 wave plate and a second lambda/2 wave plate to become S linearly polarized light. The S linearly polarized light reaches a first lambda/2 wave plate through a polarization beam splitter to be modulated into linearly polarized light, wherein an angle of 45 degrees is formed between the linearly polarized light and the original polarization direction. The linearly polarized light is emitted through a collimating mirror and an optical antenna. During receiving, an incidence light signal received by the optical antenna reaches the first lambda/2 wave plate through the collimating mirror, and is subjected to transmission and modulated into linearly polarized light of P polarization. The linearly polarized light of P polarization is output in a lossless manner through the polarization beam splitter, reaches an optical receiving module through a light gathering mirror and then is received by a detector of the optical receiving module. The optical path of the receiving light output by the polarization beam splitter is perpendicular to the optical path of the emission light entering the polarization beam splitter. The same optical antenna of the receiving end is arranged opposite to the emission end. An angle of 45 degrees is formed between fast axes of the first lambda/2 wave sheets of the receiving end and the emission end. Thus, weight and size of the system are greatly reduced; networking is convenient to perform; reliability is high; receiving signal to noise ratio is improved; and the optical antenna is especially suitable for satellite optical communication.

The invention discloses a distributed loop overlap space time code transmission method based on a bidirectional multi-relay network. The problems that the diversity gain is low, the error rate performance is poor and the detector is complex in the prior art are mainly solved. The method comprises the following implementation steps: two source nodes perform precoding on a baseband modulation signal to obtain a source node transmission signal; the two source nodes simultaneously transmit the precoded signal to all relay nodes; all the relay nodes receive the signals transmitted by the two source nodes; each relay node performs linear compression processing on the received signal, so that transmission signals on two antennas can be obtained and are transmitted to the two source nodes; and the two source nodes receive the signals transmitted by the relay nodes and construct a determination signal, and finally the determination signal is detected by employing a maximum likelihood detection method. The method has the advantages of improving the error rate performance of the system, obtaining the full diversity gain and maximum coding gain and lowering the complexity of the detector and can be used for bidirectional multi-relay network transmission.

A signal transmission method based on binary phase shift keying modulation and orthogonal frequency division multiplexing technology. The conventional bpsk signals on the frequency domain subcarriersare grouped, each packet signal is transformed into a new packet signal containing two consecutive zero signals and six BPSK signals. The new packet signal is interleaved by a channel and then subjected to an inverse Fourier transform, and the generated time domain OFDM signal is added with a cyclic prefix and sent to a communication channel. After receiving the signal, firstly, the received signal is Fourier-transformed, then inverse channel interleaved, and then the signal is grouped and demodulated. Firstly, the positions of two zeros in each grouped signal are determined based on the energy of the signal. Then, the analysis results of the other six BPSK signals are obtained according to the grouped inverse mapping relation and the traditional OFDM signal processing mechanism. The invention improves the transmission mechanism and can obtain lower transmission error rate performance than the traditional BPSK + OFDM modulation method under the same information transmission rate.