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

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 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 discloses a hydroacoustic communicating method of shallow sea remote level channel, which is characterized by the following: adopting the modulating pattern of continuous phase frequency shift keying (CPFSK) to modulate highest utility rate MSK pattern to solve envelope constant and phase mutation problem; fitting for remote shallow sea level channel; adopting coherent deexpanding pattern for communicating end to realize high-property transmission; displaying good spread-spectrum communication on the multi-path for hydroacoustic channel.

The invention discloses high-speed omni-directional wireless laser communication equipment. The equipment mainly comprises a shell, wherein, the shell is internally equipped with an MCU (micro control unit) modular circuit, a wireless encoding-decoding and modulation-demodulation modular circuit, an operational amplifier modular circuit, a filter modular circuit, an omni-directional optical antenna modular circuit, a signal processing modular circuit, a control signal interface circuit and a power supply modular circuit; and an omni-directional optical antenna, a communication interface, a control signal interface and a power interface are arranged on the shell. By utilizing the high-speed omni-directional wireless laser communication equipment, certain mobile communication equipment, terminals and electronic equipment in an aircraft and a cabin can be interlinked together so as to realize high-speed omni-directional simultaneous two-way transmission of data signals such as a speech signal, an image signal, a network signal and the like; and trivial cabling is avoided, and weight and power consumption of a system are reduced.

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 discloses a method that uses CCK code to produce the low interference window spreading code, in which, the non-cyclic self-related and non-cyclic inter-related sequences of the low interference window spreading code are less than the predetermined values in the vicinity of zero-offset, including the following steps : 1) according to the spreading gain, choose CCK code ; 2) according to the cost function being the minimum or less than the predetermined value, ensure that the associated value is minimum or less than the predetermined value CCK weight code. The low interference window spreading code can be used for time-domain spreading communication systems, better overcoming the multi-path interference of wireless channel, and meanwhile, reducing the multi-user interference; it also can be used for OFDM communication systems, processing frequency domain spreading modulation in the OFDM frequency domain, which can reduce ICI interference due to frequency shift or Doppler expansion.

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 an indoor visible light power distribution simulation calculation method including specular reflection, which solves the problem that only the diffuse reflection mode is considered in the modeling of the traditional indoor visible light communication channel. The invention mainly converts the traditional reflection mode that only considers the diffuse reflection. In order to consider the reflection method of the combination of diffuse reflection and specular reflection, and give the method used to calculate the specular reflection, it makes up for the shortcomings of incomplete consideration in the traditional channel modeling and simulation process, and is more in line with the actual scene to a certain extent. Enables further optimization of indoor visible light modeling.

The invention provides a method and system for collecting data in an SCDMA system. The system at least contains BSes, a BSC, an HLR, a data collection device, a GWF and an APP Server; the method contains the following: a plurality of BSes on an ACCO generate a paging request toward a DCE which launches a distribution establishment process of a wireless link on an ACCI; after signaling interaction with other devices, the BSes transmit allowed information of data transmission to the DCE; then data transmission is conducted between the DCE and a DTE; upon receipt of data transmitted by the BSC, the GWH transmits the data to the APP Server through an SLa interface. By adopting the invention, transmission interference of multi-paths is avoided; accurate receiving and realizing in-phase CDMA is ensured; interference among multiple accesses is reduced; system capacity is increased; the problem of aero link blockage caused by large capacity of data collection and short time of burst communication in a single time is prevented.

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 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 a satellite signal directional forwarding device. The satellite signal directional forwarding device comprises a receiving module, a control module and at least a directional transmitting antenna; the receiving module and the control module are arranged on the top of a building; the control module is connected between the receiving module and the directional transmitting antenna and is used for receiving satellite signals processed by the receiving module, adjusting the amplitude of the satellite signals, and transmitting the adjusted satellite signals to the directional transmitting antenna; and the directional transmitting antenna is disposed on the side surface of the building so as to directionally transmit the adjusted satellite signals. According to the satellite signal directional forwarding device of the invention, the receiving module is adopted to receive and process the satellite signals and transmits the processed satellite signals to the control module for amplitude adjustment; the directional transmitting antenna is adopted to transmit the adjusted satellite signals; and therefore, the building will not block and interfere the signals, and thedistortion-free directional forwarding of navigation signals can be realized.

The invention relates to a zero-intermediate-frequency spread-spectrum receiver processing module. The processing module is composed of a frequency mixer, a pseudo-code correlator, an integral cleaner, a digital loop filter, a code phase counter, a carrier complete phase counter, a code delay control circuit, a code DCO, a phase control logic, a carrier DCO and a read-write control logic; the frequency mixer is connected to the pseudo-code correlator; the pseudo-code correlator is connected to the integral cleaner; the integral cleaner is connected to the read-write control logic; the read-write control logic is connected to the code DCO and the phase control logic; the phase control logic is connected to the code phase counter; and the code phase counter is connected to the carrier complete phase counter and the carrier DCO. By means of the zero-intermediate-frequency spread-spectrum receiver processing module disclosed by the invention, the design problem of a related despreading and demodulating circuit for received signals in a navigation system is solved; the disadvantages of low secrecy performance, poor anti-interference performance and the like in the traditional radio navigation system are overcome; and thus, high-precision, high-reliability and autonomous navigation positioning of important areas in important directions can be realized.

The invention provides a high-dynamic transformation method of a broadband special network of a high-speed train. The method comprises the following steps: setting a high-dynamic converter (HIDI) on a high-speed train; setting the high-dynamic converter on a train-ground communication mode in a coverage range of ground LTE (Long Term Evolution) base station (eNode) along the line of the high-speed train; and setting the high-dynamic converter on a train-satellite mode when no ground LTE (Long Term Evolution) base station (eNode) covers along the line of the high-speed train. The method provided in the invention combines the LTE technology, the satellite navigation technology and the satellite communication technology when the high-speed train moves at 300-500 km/h, so as to provide the broadband mobile communication, the network and the multi-media service for users in the train carriage and the other users moving at a high speed.