63 results about "Spread spectrum modulation" patented technology

The invention discloses an unmanned aerial vehicle anti-collision method and system based on LoRa communication, and belongs to the technical field of risk avoidance of multiple unmanned aerial vehicles. The method comprises the following steps: constructing an ad hoc network communication architecture to realize flight state broadcast and synchronization; fusing the multi-source data by adopting a space-time alignment algorithm, and constructing a dynamic airspace situation map taking a local machine as a center; calculating a time window and space overlapping probability of the predicted intersection; a multi-priority dynamic negotiation protocol is considered, and autonomous decision making of the unmanned aerial vehicle cluster in a scene without a central node is supported; and dynamically adjusting the flight path, speed and height through a collaborative obstacle avoidance algorithm. Through a spread spectrum modulation technology and an adaptive power control mechanism, over-the-horizon communication coverage of more than 10km level is realized; through fusion of a kinematics prediction model and a risk quantification algorithm, millisecond identification and hierarchical response of collision threats are realized, a global optimal avoidance strategy is achieved, communication delay and calculation bottleneck brought by centralized decision are effectively avoided, and the real-time collaborative obstacle avoidance capability in a complex airspace is ensured.

The invention discloses an anti-multipath and anti-frequency offset satellite communication method based on chirp spread spectrum modulation joint architecture, and relates to the technical field of satellite or data chain communication, the method comprises the following steps: mapping input K bit information into a modulation symbol K, K belongs to {0, 1,..., N-1}; s02, a corresponding chirp baseband signal s [n] is generated according to the modulation symbol K, and the expression of the chirp baseband signal s [n] is as follows: n = 0, 1,..., N-1; and S03, carrying out digital-to-analog conversion on the chirp baseband signal. According to the invention, through integrated design of spread spectrum and modulation depth, and by use of the complete orthogonal autocorrelation characteristic of chirp signals and an FFT demodulation mechanism, the problems that a traditional architecture has significant bottlenecks in the aspects of resource efficiency, dynamic adaptability, anti-interference capability and the like and is difficult to meet high-performance communication requirements in a high-speed moving and complex multipath scene are effectively solved; the anti-multipath and anti-Doppler performance is significantly improved, and the calculation and resource overhead of the receiving end is greatly reduced.

The invention discloses an unmanned aerial vehicle formation communication system based on a LoRa technology and a method thereof. The communication system comprises a ground control unit, a main control processing unit, a sensing array unit, a power supply management unit and a mobile communication unit. The ground control unit generates a formation flight scheme, and the main control processing unit fuses RTK positioning data to generate a dynamic control instruction; the mobile communication unit constructs a radio data transmission module based on a LoRa technology, supports dynamic switching between an ESP-NOW broadcast mode and a TCP transparent transmission mode, and realizes low-delay instruction transmission and low-power-consumption data interaction. The sensing array unit integrates an RTK positioning module and an inertial measurement unit, monitors the state of the unmanned aerial vehicle in real time, and ensures that the formation spacing error is less than 10cm. Through long-distance low-power-consumption communication and power and frequency band dynamic optimization of the LoRa technology, in combination with high-precision positioning and anti-interference spread spectrum modulation, large-scale formation synchronization efficiency and flight stability are remarkably improved, and the method is suitable for scenes such as agriculture, rescue and cluster performance and has the advantages of low cost and high reliability.

The invention relates to a spread spectrum underwater acoustic communication coding and decoding method, which comprises the following steps of: performing dual-channel coding modulation, sequentially performing CRC (cyclic redundancy check) coding, serial-parallel conversion, multi-system error correction coding and interleaving operation on an information bit stream at a transmitting end, then performing spread spectrum modulation on a code element by using a pseudorandom sequence, and finally mapping modulation output of an I channel and a Q channel into a baseband signal, and a spread spectrum underwater acoustic communication signal is formed through pulse shaping and up-conversion processing. According to the method, the communication accuracy is improved through a dual-channel incoherent and coherent redundancy decoding mode and an opportunity cross validation decoding mode.

Method for transmitting digital data between a bottom hole assembly and a surface assembly of a drilling rig, wherein at least one of the bottom hole assembly and the surface assembly comprises a transmitting transducer actuatable to generate acoustic waves propagating in a drilling fluid and the other of the bottom hole assembly and the surface assembly comprises a receiving transducer configured to detect acoustic waves, comprising the following steps : processing in sequence the data by means of convolutional coding, an interleaving operation and at least one spread spectrum modulation technique, obtaining a processed digital signal; - converting the processed digital signal into an analog signal; - actuating the transmitting transducer in such a way as to generate, in the drilling fluid, acoustic waves that correspond to the analogue signal; receiving the analog signal through the receiving transducer; converting the analog signal into a received digital signal; - processing in sequence the digital signal received by means of at least one demodulation technique, one "de- interleaving" operation and one convolutional decoding, obtaining the received data.

A signal transmission method based on constellation-aided LoRa modulation includes: a modulated bit sequence and a phase shift keying (PSK) bit sequence are obtained, and the modulated bit sequence is subjected to Gray mapping and spread spectrum modulation to generate a LoRa signal set; the PSK bit sequence is subjected to PSK constellation mapping based on a preset constellation point coordinate set to output a PSK constellation point set; the LoRa signal set is subjected to PSK modulation based on a preset imaginary unit and the PSK constellation point set to generate a transmission signal; a complex number sequence is generated based on the transmission signal and a preset raw down chirp signal; and real-imaginary part judgment is performed on the complex number sequence to output a LoRa modulation information sequence set and a PSK symbol judgment result. A signal transmission system based on CA-LoRa is further provided.

The application discloses a three-level inverter harmonic suppression method based on zero vector symmetrical reconstruction and spread spectrum composite modulation, and the method comprises the following steps: step 1, signal acquisition and voltage instruction acquisition; step 2, spread spectrum modulation parameter setting; step 3, basic vector action time calculation; step 4, zero vector symmetrical reconstruction of vector sequence; step 5, switch time calculation and register updating; and step 6, PWM signal generation and system closed loop operation. The application realizes full-band suppression of inverter output PWM harmonics by deeply fusing the zero vector symmetrical reconstruction technology and the spread spectrum modulation technology. The application can be applied to a permanent magnet synchronous motor driving system powered by a three-level voltage source inverter, can simultaneously suppress the PWM harmonic amplitude near the odd carrier frequency and the even carrier frequency, effectively reduces electromagnetic vibration and noise, and has extremely high application value in the field of high-power inverters and motor drives.

Various embodiments comprise systems, methods, architectures, mechanisms or apparatus providing far-field wireless charging of implanted medical devices, Internet of Things (IoT) and the like via a leader radio configured for receiving spread spectrum (SS) modulated radio waves from a plurality of slave radios within an area including the leader radio and a target device, for receiving from the target device backscatter radio energy associated with the (SS) modulated radio waves, and for generating slave radio control signals; the leader radio, in a charging mode of operation, being configured for determining changes in received power associated with backscatter radio energy received from the target device and responsively transmitting control signals toward the slave radios configured to cause the slave radios to modify respective radio wave transmission times such that slave radio wave transmissions are substantially phase aligned when received at the target device.

The present invention belongs to the technical field of signal detection and estimation, and more specifically relates to a method for blindly estimating LoRa signals based on linear frequency modulation characteristics. The method of the present invention mainly uses the carrier frequency to down-convert the intercepted LoRa signal, utilizes the linear spread spectrum modulation characteristics of the LoRa signal to estimate the frequency modulation slope parameters of the LoRa signal, and uses the estimated parameters to further estimate the remaining parameters of the signal. Finally, by limiting the parameters of the LoRa signal, a more accurate estimate is obtained, thereby achieving the purpose of blindly estimating the LoRa signal parameters.

The invention discloses an integrated parallel transmission method and device for a photoelectric time-frequency signal, and the method comprises the steps: generating a broadband spread spectrum modulation intermediate-frequency carrier signal through a time-frequency modem, and carrying out the phase modulation through an up-converter and an electro-optical modulator, and obtaining an A-station ultra-stable laser and a B-station laser; a photoelectric detector obtains a downlink microwave modulation signal through coherent detection, and the downlink microwave modulation signal passes through a down converter and a time-frequency modem to obtain frequency deviation of a station A and a station B; the A station and the B station generate optical heterodyne signals respectively, optical phase locking control is completed through an acousto-optic modulator, and the frequency of the laser of the B station is adjusted through feedback, so that the laser of the B station is locked to the ultra-stable laser of the A station. According to the integrated parallel transmission method for the photoelectric time-frequency signals, three kinds of time-frequency signals are transmitted in parallel through a single optical carrier in a frequency division multiplexing mode of a time-frequency signal frequency spectrum layer, dispersion of multiple transmission channels is avoided, and therefore the time domain coherence characteristic between the time-frequency signals is better guaranteed.

The invention discloses a phase-locked loop chip, a frequency switching method of the phase-locked loop chip and display equipment, in the phase-locked loop chip, a control module configures a reference clock signal for a phase-locked loop circuit and generates and sends a clock switching control signal; the spread spectrum modulation circuit generates a frequency modulation step value according to the frequency division coefficient and the modulation coefficient under the control of the clock switching control signal; and the phase-locked loop circuit performs frequency adjustment on the feedback clock signal by using the frequency modulation step value to generate an output clock signal, wherein the frequency of the output clock signal is consistent with that of the reference clock signal. Because the frequency modulation step value is determined according to the frequency division coefficient and the modulation coefficient of spread spectrum modulation, the frequency modulation step value is used for frequency adjustment, so that the lock loss abnormity can be effectively avoided, the system stability is improved, the spread spectrum modulation circuit is multiplexed, other devices do not need to be additionally arranged, the chip cost is reduced, and the power consumption is reduced. And a small-step multi-frequency frequency approximation mode is adopted, so that the frequency switching time is shortened, and the chip performance is improved.

The invention relates to a target sensing method based on a communication signal, and the method comprises the steps: receiving a communication signal transmitted by an active target, the communication signal being a signal combining frequency shift keying and linear frequency modulation spread spectrum modulation; carrying out carrier demodulation on the communication signal to obtain a double-channel baseband signal; performing digital beam forming processing on the double-channel baseband signal to obtain sum beam data and difference beam data; performing matched filtering processing on the sum beam data and the difference beam data; performing multi-pulse coherent accumulation processing on a matched filtering result to obtain distance-Doppler information; determining angle information of the active target based on a ratio relationship between the sum beam data and the difference beam data; and determining the distance, Doppler velocity and angle of the active target according to the distance-Doppler information and the angle information.

The invention discloses a spread spectrum signal tracking method and system, and belongs to the field of signal processing. According to the invention, the spread spectrum digital signal is generated by performing oversampling on the acquired spread spectrum modulation signal. In-phase and quadrature components are generated by performing mixing, de-spreading and coherent integration on the digital signal, and frequency and phase error information is calculated based on the components at continuous moments for correcting local carriers. The corrected local carrier is then utilized to mix the signal to a baseband, and a target fractional delay is determined by applying an adjustable fractional delay and searching for an instant correlation energy peak to obtain code phase error information. After the code phase error information is utilized to correct the local pseudo code, the corrected local carrier and local pseudo code are utilized to initialize a narrow-bandwidth frequency-locked loop, a phase-locked loop and a delay-locked loop so as to start accurate tracking, and high-precision stable locking of spread spectrum signals can be realized in a short time.

The invention discloses a linear frequency modulation spread spectrum modulation system and modulation method based on a neural network, which are realized by converting a CSS modulation process into a neural network component, support the generation of various CSS variant signals, and are compatible with various neural network platforms at the same time. The method comprises the following steps: firstly, mapping input effective load data into a starting frequency vector by adopting a frequency selection module, and providing an accurate frequency starting point for subsequent modulation; secondly, the frequency modulation module generates a CSS signal component through a transposition convolution layer; and finally, the complex signal generation module converts the modulation result into a standard complex signal format, and ensures that the output signal is completely compatible with the existing SDR platform and the commercial LoRa receiving node. According to the method, the basic neural network component is utilized, the problems that an existing CSS modulator is poor in expandability and hardware portability are solved, and an efficient and flexible modulation scheme compatible with various CSS variants is provided for application of the Internet of Things.

This application discloses a method and system for tracking spread spectrum signals, belonging to the field of signal processing. This application generates a spread spectrum digital signal by oversampling the acquired spread spectrum modulated signal. In-phase and quadrature components are generated by mixing, despreading, and coherent integration of this digital signal. Frequency and phase error information are calculated based on the components at continuous time intervals to correct the local carrier. The corrected local carrier is then used to mix the signal to baseband. An adjustable fractional delay is applied, and the instantaneous correlation energy peak is searched to determine the target fractional delay, thereby obtaining code phase error information. After correcting the local pseudocode using this code phase error information, the corrected local carrier and local pseudocode are used to initialize a narrow-bandwidth frequency-locked loop, phase-locked loop, and delay-locked loop, thus initiating precise tracking. This enables high-precision and stable locking of the spread spectrum signal in a short time.

The invention relates to the technical field of liquid crystal display, in particular to a control method and device of a display panel, a time sequence control circuit and the display panel, which are used for enabling a spread spectrum modulation range to be relatively large, ensuring signal stability, improving EMI (Electro-Magnetic Interference) suppression efficiency and reducing hardware cost, and the device comprises the following steps: detecting a starting time point of a first image frame; the clock reference of data transmission and display of the first image frame is a first clock frequency; the first clock frequency is any clock frequency in the spread spectrum parameter sequence; the identification unit is used for identifying an idle time period of the first image frame based on the starting time point of the first image frame; the trigger unit is used for generating a first trigger signal, and the first trigger signal is used for triggering the clock generator to switch the clock frequency; and the clock generator is used for selecting a second clock frequency from the spread spectrum parameter sequence in response to the first trigger signal, and outputting a second clock signal with the second clock frequency in the idle time period of the first image frame.

The invention provides a radio station adaptive joint coding modulation method applied to a severe channel environment, and the method supports interconnection and intercommunication of a plurality of radio stations, and comprises a transmitting end and a receiving end. Wherein the data processing process of the sending end is as follows: data to be sent and a reference signal form a data frame according to a frame format, and scrambling interleaving processing is carried out; performing polarization coding on the processed data frame; sCMA coding is carried out; self-adaptive chirp spread spectrum modulation is carried out; the data processing process of the receiving end is as follows: the receiving end radio station synchronizes the received chirp modulation signal and then performs incoherent demodulation; channel signal-to-noise ratio estimation is carried out; sCMA multi-user detection is carried out on the demodulated data information; and performing CRC (cyclic redundancy check). According to the invention, interconnection and intercommunication of a large number of radio stations can be realized by occupying less time-frequency resources in a severe channel environment.

The application relates to a Gold sequence spread spectrum underwater acoustic modulation and demodulation method against strong multipath interference, relating to underwater acoustic communication. The method comprises the design of a transmitting end modulation and a receiving end demodulation; on the basis of a traditional Gold sequence spread spectrum modulation and demodulation technology, a molecule set method is adopted to divide the traditional GSSS code set into multiple subsets, and different subsets are adopted in the modulation process of each symbol, so that weak correlation is ensured between each symbol. The demodulation process is based on the molecule set modulation method of the modulation process, energy detection is carried out according to the corresponding local GSSS code subset symbol by symbol, the number of bits carried by each symbol is calculated, each bit soft information is calculated, the soft information is input into an interleaver and a channel decoder, and the original information is correctly demodulated. The method overcomes the problem that the traditional GSSS modulation and demodulation technology cannot be correctly demodulated in a strong multipath environment, improves the robustness of the GSSS modulation and demodulation technology to the strong multipath underwater acoustic channel, and realizes stable and robust communication in the strong multipath environment.

The invention relates to the technical field of Internet of Things control, and discloses an Internet of Things control method and system integrating satellite time service and spread spectrum communication, and the method combines high-precision time synchronization provided by a satellite time service technology and high-reliability data transmission provided by a spread spectrum communication technology. The overall performance of the Internet of Things control system is effectively improved, and the system comprises a satellite time service module configured to receive satellite signals and realize time synchronization, and a spread spectrum communication module configured to perform spread spectrum modulation, transmission and demodulation of data. The method is suitable for various Internet of Things application scenes, can ensure the time synchronization precision of the system, enhance the anti-interference capability of communication, and improve the security of data transmission and the reliability of the system, thereby optimizing the coordination control and data exchange of Internet of Things equipment, and having wide application prospects and remarkable technical advantages.

A circuit includes a switching converter, an oscillator, and a spread spectrum modulator (SSM). The oscillator has a modulation input and a clock output. The clock output is coupled to the switching converter. The oscillator is designed to generate a clock signal at its clock output with a frequency based on a modulation signal at its modulation input. The SSM has a modulation output that is coupled to the oscillator's modulation input. The SSM is designed to generate the modulation signal at its modulation output while adjusting the rate of change of the modulation signal based on the magnitude of the modulation signal at a boundary of a modulation period.

The invention relates to a spread spectrum modulator. A circuit (400) includes a switching converter (110), an oscillator (130), and a spread spectrum modulator (SSM) (420). The oscillator (130) has a modulated input and a clock output. The clock output is coupled to the switching converter (110). The oscillator (130) is configured to generate a clock signal at the clock output having a frequency based on a modulated signal at the modulation input. The SSM (420) has a modulated output coupled to the modulated input of the oscillator. The SSM (420) is configured to generate the modulated signal at the modulation output while adjusting a rate of change of the modulated signal based on a magnitude of the modulated signal at a boundary of a modulation time period.

The application relates to a cold-chain logistics tracking method and system, which comprises the following steps: acquiring the unique identification code, space-time information and multi-dimensional preservation information of a plurality of commodities, wherein the multi-dimensional preservation information comprises temperature, humidity, pH value and marker gas content; based on maximum information entropy and a multivariate autoregressive model, the time domain characteristics and frequency domain characteristics of the multi-dimensional preservation and corresponding space-time information of each commodity are extracted; pseudo-noise sequences are used to spread spectrum modulate the time domain characteristics, frequency domain characteristics and unique identification code to generate a plurality of traceability codes; based on the traceability codes and preservation information, a self-encoder based on a convolutional neural network is trained; real-time traceability information of a commodity to be traced is input into the trained self-encoder to obtain one or more traceability codes. The unique identification code, preservation information and space-time information are spread spectrum modulated with a watermark, and the self-encoder is used for identification, so that the timeliness of cold-chain logistics tracking and the non-tamperability of traceability data are improved.

A satellite communication system includes a server system and a transceiver array communicatively positioned between the server system and a satellite ground station. The transceiver array is operable to receive a modulated signal from the satellite via the satellite ground station, demodulate the signal into a digital packet, and send the digital packet via internet protocol (IP) to the server system. The server system reads an identify of a recipient device from the packet and operates the transceiver array to modulate the packet by spread spectrum modulation and send the packet to the recipient device via a designated band of frequency of spectrum to a satellite.

The invention relates to a method and a system for monitoring and positioning multiple types of faults of a submarine direct-current multi-path cable, and the method comprises the steps: selecting m sequences with different code element durations according to the length of a detected cable, and multiplying the m sequences by a chaotic sequence mapped by improved Logistic to obtain an improved chaotic sequence; performing spread spectrum modulation on the improved chaos sequence and a sine wave to form a transmitting signal; transmitting signals are sequentially injected into the test points of the tested cables; collecting reflected signals of each path of tested cable, and estimating time delay between the transmitted signals and the reflected signals to judge whether each path of cable has a fault and a corresponding fault type; and based on the time delay and the cable parameters of the corresponding path, realizing accurate fault positioning through a deep learning algorithm. Compared with the prior art, high interference resistance, multi-path cyclic monitoring and automatic fault type judgment can be realized at the same time, and adaptive compensation can be carried out on environmental factors.

The present invention discloses a method for generating synchronization sequences for low-orbit satellite broadband communications based on linear frequency modulation. The method comprises the following steps: generating up-and-down chirp frequency signals using a fractional slope coefficient of linear frequency modulation spread spectrum modulation; generating up-and-down chirp phase signals using a phase-frequency relationship; generating up-and-down chirp time domain signals using a phase signal index; generating a signaling signal using the slope coefficient and modulation symbol value of the linear frequency modulation spread spectrum; and generating a synchronization sequence frame structure using the generated up-and-down chirp and signaling signal. When applied to a low-orbit satellite broadband communication system, the present invention can achieve time-frequency synchronization in low signal-to-noise ratio and large-scale Doppler frequency shift environments. It can also flexibly adjust the sequence frequency domain position to avoid partial interference in the synchronization channel, thereby improving the anti-interference capability of the synchronization system.

The invention relates to an underwater laser time service system and method based on spread spectrum communication. The underwater laser time service system comprises a time service end and a time-served end. The time-served end performs spread spectrum modulation on local time and drives a laser to send an optical signal to an underwater channel; after receiving the time signal of the time-served end, the time service end carries out de-spreading processing, compares the time signal with a local high-precision time signal, carries out spread spectrum modulation on the comparison result and the local high-precision time signal, and then sends the result to an underwater channel; and after receiving the time service optical signal of the time service end, the time service optical signal is compared with the local time, and the absolute time difference between the time service optical signal and the local time is solved, so that time synchronization is completed. The anti-interference performance and confidentiality of laser signals in the underwater environment can be improved through spread spectrum modulation, long-distance transmission is achieved by combining the high transmissivity of blue and green light bands in the underwater, and finally high-precision time synchronization of the time service end and the time-served end is achieved. The method can effectively solve the problems of low underwater sound time service precision, large delay and large underwater time service attenuation of radio waves, and is especially suitable for underwater cluster time service scenes such as underwater navigation, ocean exploration and collaborative operation.

An automotive Ethernet physical-layer (PHY) transceiver includes an Analog Front End (AFE) and a digital processor. The AFE is coupled via a full-duplex Ethernet link to a peer transceiver. The AFE is configured to receive from the peer transceiver, over the full-duplex Ethernet link, an analog Ethernet signal conveying data symbols, at a reception data rate that is lower than a transmission data rate used in transmitting data from the PHY transceiver to the peer transceiver, the Ethernet signal being modulated by a spreading sequence having a Spreading Factor including a ratio between a spreading chip-rate and the reception data rate, and to convert the received analog Ethernet signal into a digital signal. The digital processor is configured to de-spread the digital signal using the spreading sequence to recover the data symbols.

The application relates to a target sensing method based on a communication signal, which comprises the following steps: receiving a communication signal transmitted by an active target, wherein the communication signal is a signal combined by frequency shift keying and linear frequency modulation spread spectrum modulation; performing carrier demodulation on the communication signal to obtain a double-path baseband signal; performing digital beam forming processing on the double-path baseband signal to obtain sum beam data and difference beam data; respectively performing matching filtering processing on the sum beam data and the difference beam data; performing multi-pulse coherent accumulation processing on the matching filtering results to obtain distance-Doppler information; determining angle information of the active target based on a ratio relationship between the sum beam data and the difference beam data; and determining the distance, Doppler velocity and angle of the active target according to the distance-Doppler information and the angle information.

The invention provides an ultraviolet communication channel coding method and system, and is applied to the technical field of ultraviolet communication, and the method comprises the steps: carrying out the fountain code coding of to-be-transmitted data, and obtaining a plurality of coding packets; performing spread spectrum processing on the coding packet based on the spread spectrum code to obtain a plurality of pieces of spread spectrum information; modulating the spread spectrum information to obtain modulation information; modulation information is transmitted to an atmospheric channel based on the ultraviolet photons. According to the ultraviolet communication channel coding method provided by the invention, the to-be-transmitted information is subjected to coding, spectrum spreading and modulation processing, so that the data transmission capability between the transmitting end and the receiving end is improved, the probability of data packet loss and error code occurrence in the ultraviolet communication transmission process is remarkably reduced, and the ultraviolet communication efficiency is improved.