33results about How to "Overcoming multipath interference" patented technology

The invention belongs to the field of radars and provides an excitation source circuit module for a micro radar; the excitation source circuit module comprises a mono-stable pulse generation circuit, a mono-stable pulse delay circuit and an excitation pulse output circuit, wherein the mono-stable pulse generation circuit is used for outputting a pulse signal with a certain pulse width; the mono-stable pulse delay circuit is connected with the mono-stable pulse generation circuit and used for receiving the pulse signal output by the mono-stable pulse generation circuit and outputting a delay pulse signal; and the excitation pulse output circuit is connected with the mono-stable pulse delay circuit and used for performing delay treatment of the pulse signal and outputting a periodic pulse signal. According to the invention, a forward narrow pulse signal with a certain pulse width is generated by the mono-stable pulse generation circuit; a certain delay time is formed by the mono-stable pulse delay circuit; after being subjected to the delay treatment, the pulse signal forms the periodic pulse signal through the excitation pulse output circuit and is output to a radar excitation circuit; the signal receiving and transmitting isolation of the radar is increased; and the multi-path interference of echo after being reflected and refracted for many times on the radar is avoided.

The invention provides a clock synchronization method and a terminal machine. The clock synchronization method comprises the following steps: receiving a first transmission frame sent by a second terminal machine connected with a first terminal machine, wherein the first transmission frame includes a pilot sequence and user data, and at least part of data of the pilot sequence can be used as a cyclic prefix in the first transmission frame to eliminate the multi-path interference to the transmission channel between the first terminal machine and the second terminal machine; acquiring time error information based on the first transmission frame, wherein the time error information is used to indicate the phase difference between a first clock signal generated when the second terminal machine sends the first transmission frame and a second clock signal generated when the first terminal machine receives the first transmission frame; determining a first sampling point for sampling the user data in the first transmission frame and a second sampling point for sampling the pilot sequence in the first transmission frame based on the time error information; and carrying out clock synchronization between the first terminal machine and the second terminal machine based on the first sampling point and the second sampling point.

The invention discloses a cooperation source electromagnetic wave space structure correlation information-based antenna pointing direction induction method and belongs to the fields of electromagnetic wave navigation and signal parameter estimation. The method comprises the steps of firstly determining a correlation matrix between each cooperation source wave structure vector and a signal source electromagnetic wave space structure; then receiving phase shift key control signals in the cooperation source by 1 antenna unit in a polarized sensitive electromagnetic vector sector so as to obtain the polarized oval dip angle of each signal; solving the included angle between each signal arrival vector and the antenna pointing direction according to the signal source electromagnetic wave space structure correlation matrix and the polarized oval dip angles thereof; converting an antenna pointing vector under a receiver coordinate system into a reference source wave structure coordinate system according to the polarized oval dip angle of each signal and the included angle between each signal arrival vector and the antenna pointing direction, and then converting into a geological coordinate system, thus finishing the sensing of the antenna pointing direction of the receiver. The cooperation source electromagnetic wave space structure correlation information-based antenna pointing direction induction method can replace sensors such as a magnetic heading sensor, a gravity direction sensor and a north seeker, and can also be applied to the heading / gesture measuring of a motion platform.

The invention discloses infrared wireless network equipment applied in a satellite capsule. The infrared wireless network equipment applied in the satellite capsule comprises a satellite host computer and satellite-borne electronic equipment, and further comprises an infrared wireless access point and an infrared wireless terminal. The infrared wireless access point is connected with the satellite host computer, and the infrared wireless terminal is connected with the satellite-borne electronic equipment. The infrared wireless terminal comprises a wired interface module A, an infrared optical antenna A, a slave control module and an infrared control module A. The infrared wireless access point comprises a wired interface module B, an infrared optical antenna B, a host control module and an infrared control module B. According to the infrared wireless network equipment, an infrared wireless optical communication way replaces a traditional satellite bus communication way, traditional communication cables among satellite-borne electronic equipment is eliminated, interconnection among electronic equipment inside a satellite is achieved, complexity of connection through the traditional cables is avoided, electromagnetic interference of wireless radio frequency communication is avoided, and the weight of the satellite is lightened effectively.

The invention provides a flight measurement system and a flight measurement method, and solves the technical problem that the existing RTK measurement system cannot perform accurate measurement in a sunken terrain. The system comprises a GNSS receiver used for receiving satellite signals and base station data chain and correction data to form positioning data; a laser ranging device used for measuring the height difference between the unmanned aerial vehicle and the ground when the unmanned aerial vehicle hovers to form correction data; and the unmanned aerial vehicle used for bearing the GNSSreceiver and the laser ranging device and controlled to be suspended to an appointed position. The hovering height of the unmanned aerial vehicle is utilized to avoid multipath interference of homologous wireless signals and improve the receiving sensitivity of the wireless signals. The relative height difference between the unmanned aerial vehicle and the measured position on the ground is obtained by using the mature technology of laser ranging to form correction data, so that the unmanned aerial vehicle can flexibly adjust the hovering height to overcome complex near-field obstacles, the positioning measurement precision of the ground position is ensured, and a reliable guarantee is provided for realizing flexible fixed-point measurement and range measurement.

The invention aims to provide a remote underwater sound communication method and belongs to the technical field of underwater sound communication. The method is based on demodulation and decoding combined iterative detection of differential encoding. A transmitter resists multi-path interference by using spread spectrum communication, the problem of phase jump and loop cycle skipping is solved by using differential modulation quadrature differential phase shift keying with high frequency spectrum utilization rate, and the transmitter adopts demodulation and decoding combined iterative technology to eliminate inter-code interference. The method has the beneficial effects that 1) the error bit rate performance of a remote underwater sound communication system is improved by the demodulation and decoding combined iterative technology; 2) the technical requirement on a non-linear amplifier is reduced by differential modulation, and differential modulation has engineering feasibility; and 3) the multi-path interference of a remote underwater sound channel is overcome by spread spectrum communication.

The invention relates to a wireless digital single channel or multi channel video, voice and data mobile transmission equipment. The invention consists of front end digital picking-up transmitter, digital repeat relay transmitter and terminal digital receiver, front end digital picking-up transmitter divides into one-way front end digital picking-up transmitter and multi-channel front end digitalpicking-up transmitter, one-way front end digital picking-up transmitter at most picks up one-way video, two-way voice and one-way data signal and concurrently transmits to multi-channel front end digital picking-up transmitter or terminal digital receiver, multi channel front end digital picking-up transmitter can gather self-collected video, voice and data signal based on receiving multiple one-way front end digital picking-up transmitter and transmits to terminal digital receiver, all front end digital picking-up transmitters can forward radio frequency signal to terminal digital receiversvia digital repetition relay transmitter at far from terminal digital receiver.

The invention discloses a CDMA (code division multiple access) communication method. The invention relates to a CDMA communication method which is designed for solving the problem that a CP (cyclic prefix) is introduced in an OFDM (orthogonal frequency division multiplexing) system in the current communication method, thereby wasting bands. The method is traditionally implemented based on a BS-CDMA (block spread-code division multiple access) system; a transmitting method for the transmitting ends of a downlink and an uplink comprises the step of sequentially carrying out spectrum spreading, serial-parallel conversion, multiplication with M paths of sub-carriers, parallel-serial conversion, digital-to-analog conversion, carrier modulation and band-pass filtering on data to be transmitted by a user so as to transmit the signals subjected to band-pass filtering to a channel; and a receiving method for the receiving ends of the downlink and the uplink comprises the steps of sequentially carrying out band-pass filtering, demodulation, low-pass filtering, analog-to-digital conversion, serial-parallel conversion, multiplication with M paths of sub-carriers, low-pass filtering, parallel-serial conversion, despreading, and integration and judgment in a bit time Tb on the signals transmitted by a receiving channel of a receiving antenna, and outputting the signals. The method disclosed by the invention is suitable for carrying out wireless communication.

The invention provides a navigation angle measurement method based on quantum entanglement microwave and a realization apparatus thereof. In this method, two paths of quantum entangled microwave signals are transmitted locally, and the time interval of the two adjacent measurements is obtained by orthogonal component correlation detection at a receiving end to further obtain a target azimuth angle. The navigation angle measuring apparatus is composed of a ground emitting part and an airborne receiving part, wherein the ground emitting part comprises an entangled microwave generator, a delay device, a horizontally polarized antenna and a vertically polarized antenna, and the airborne receiving part comprises a horizontally polarized antenna, a vertically polarized antenna, an amplifier, an oscillator, an IQ orthogonal branch detector, a data processor and a display. The safety performance and anti-interference capability during navigation angle measurement are improved, which is of great importance under complex electromagnetic environments.

The invention discloses a multi-mode mine mobile communication system which comprises a control unit, a tree structure passive optical network, a downhole explosion-proof MIMO base station, a downhole explosion-proof SISO base station, a distributed MIMO antenna and a downhole mobile terminal. Multiple modes are dynamically adopted for the system in operation, wherein in the SISO mode, SISO signals are processed through the system by means of a communication gateway of the distributed MIMO antenna and a far-end antenna unit; in the MIMO mode, MIMO output signals are processed through the system by means of the communication gateway of the distributed MIMO antenna and a far-end antenna unit group; in the mixed mode, the SISO signals and the MIMO output signals are processed through the system by means of the communication gateway of the distributed MIMO antenna and antenna unit groups. The system is simple in structure, flexible in deployment, large in the channel capacity, high in anti-jamming capability, wide in network coverage area, capable of overcoming near-far effects, eliminating communication dead zones and meeting the requirements for mining specific operating environments and security and applicable to underground coal mine mobile communication and mobile monitoring.

The invention discloses a frequency hopping pulse bit encoding underwater acoustic communication method based on linear frequency modulation signals. The method comprises the steps of utilizing the characteristic that time slots are not overlapped in underwater multipath interference, adopting modulation combination of frequency modulation encoding and pulse bit encoding to conduct modulation on information, increasing the number of the time slots of each frame by increasing the quantity of frequency hopping to improve the time length of each frame, enabling the delay spread of most multipath signals to be smaller than the duration time of each frame, and utilizing a filter for extracting main path signals from a frequency domain at a receiving terminal. According to the frequency hopping pulse bit encoding underwater acoustic communication method based on the linear frequency modulation signals, on the premise that the multipath interference resistance performance is ensured, devices of a transmitting terminal and the receiving terminal are simplified, the power required by transmission is reduced, the speed of data transmission is increased, and the defects that a traditional underwater acoustic communication technology is complex in device, large in power consumption, large in multipath interference on information, slow in transmitting speed and the like are overcome.

The invention relates to a method for receiving a long scrambling code of a downstream cluster service in a time division duplex communication system, which comprises the steps as follows: a base station broadcasts and transmits system data information with the long scrambling code to a target user group in the cell; user equipment estimates channel impulse responses for training sequences in the cell and in the neighboring cells according to the received system data information to obtain the channel impulse responses corresponding to each cell; the power of the channel impulse responses of each cell is estimated to obtain the power of the channel impulse responses corresponding to each cell, and the power of the channel impulse responses is sorted to determine the cells with effective receptions; and the rake reception and interference elimination, demodulation and decoding process are carried out cell by cell to the cells with effective receptions so as to obtain expected user data. Based on the method, the invention also provides a receiver-transmitter unit for realizing the method. The invention effectively overcomes the multi-cell interference, so as to improve the transmission performance of the cluster mass-sending service and the cell capacity.