82 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.

A control method for suppressing high-frequency howling of a permanent magnet synchronous motor relates to the field of motor control and noise suppression, and includes the following steps: Step 1: Considering the influence of rotor position on pulse width modulation, design a segmented hybrid switching frequency modulation strategy: Step 2: Simulate and determine the frequency, spread spectrum width and proportional coefficient of the triangular wave periodic function in the segmented hybrid switching frequency modulation strategy, Step 3: According to Step 1 and Step 2, obtain the change value of the switching frequency with the rotor position, and output six-way drive signals after space vector pulse width modulation, which are used to control the on and off of the switch tube of the permanent magnet synchronous motor driver inverter, so as to achieve the purpose of suppressing the high-frequency howling of the permanent magnet synchronous motor. The present invention suppresses high-frequency sideband harmonics, thereby suppressing the high-frequency howling of the permanent magnet synchronous motor. The method is low-cost, easy to implement, and does not need to add additional hardware equipment; a segmented hybrid switching frequency spread spectrum modulation strategy is set to better disperse and suppress high-frequency current harmonics and high-frequency howling noise.

A communication method that includes using a software app on a local computing device to initiate sending a message to a recipient, determining that a cellular network is not available to the app, and sending, by the app, the message as a digital packet by a personal area network (PAN) connection to a device paired with the local computing device. The device uses chirp spread spectrum modulation to send the packet in an L-band of spectrum to a satellite

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 relates to a chaotic spread spectrum modulation multi-user access system of a joint PPM for short-distance communication. At the transmitting end, a chaotic signal is generated by a chaotic mapping method, and the chaotic signal is used as a reference segment of the first time slot, and a bit stream is divided into multiple symbol periods, each symbol period is mc+1 bit transmission bits, wherein mc mapping bits determine the selected pulse position of PPM, and 1 bit is modulated by DDCSK-WC; when multiple users transmit information at the same time, the information segment is redesigned by using an orthogonal Walsh code, and then the redesigned information segment is transmitted at the pulse position selected by PPM; at the receiving end, the received signal is multiplied by a corresponding Walsh code according to a certain method, and then the reference segment processed by the Walsh code and the information segment are calculated for correlation characteristics, and the position of the information segment is determined by comparing the absolute value of the correlation characteristic result, thereby judging the corresponding mc mapping bits and 1 modulation bit. The present invention effectively improves data transmission efficiency.

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.

A communication method that includes using a software app on a local computing device to initiate sending a message to a recipient, determining that a cellular network is not available to the app, and sending, by the app, the message as a digital packet by a personal area network (PAN) connection to a device paired with the local computing device. The device uses chirp spread spectrum modulation to send the packet in an L-band of spectrum to a satellite

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 present invention discloses a random modulation method and system for a permanent magnet motor servo drive system, belonging to the technical field of motor control. The random modulation method for a permanent magnet motor servo drive system includes: obtaining the real-time speed of the permanent magnet motor and setting the parameters of the permanent magnet motor; determining the carrier ratio based on the real-time speed of the permanent magnet motor and obtaining the carrier ratio influence factor; constructing an extended frequency envelope function by using the carrier ratio influence factor; determining the random spread spectrum period according to the extended frequency envelope function; and implementing modulation based on the random spread spectrum period. The random modulation method for a permanent magnet motor servo drive system of the present invention comprehensively considers the influence of the carrier ratio and the spread spectrum range on the motor control performance, fully exerts the harmonic dispersion effect brought by the spread spectrum modulation, and effectively reduces the adverse influence of the traditional random modulation on the motor control performance under the condition of a low carrier ratio.

The invention provides a data transmission device, method and equipment. The data transmission device comprises a LoRa receiving and transmitting module and a wireless communication module, wherein the LoRa receiving and transmitting module sends a first data message to the wireless communication module; the LoRa transceiver module performs a first round of query to determine whether a first acknowledgement message is received; under the condition that the LoRa receiving and transmitting module does not receive the first confirmation message in the first round of query, the LoRa receiving and transmitting module triggers to send the first data message to the wireless communication module again, and performs a second round of query to determine whether the first confirmation message is received or not; sending a first connection request to the wireless communication module under the condition that the first confirmation message is queried and received in the first round of query; and the wireless communication module performs spread spectrum modulation on the first data message based on the first connection request to obtain a first spread spectrum data message, determines first sending power based on the communication condition of the wireless communication module and the network server, and sends the first spread spectrum data message at the first sending power.

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.

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 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 invention discloses an improved Lorenz chaos spread spectrum EMI (Electro-Magnetic Interference) reduction method based on a Buck converter, which relates to an electronic switching power supply technical method, and adopts a switching tube driving signal of an improved Lorenz chaos spread spectrum modulation method converter to control. And electromagnetic noise energy concentrated at the switching frequency and the frequency doubling position is dispersed to a wider frequency band, so that the conducted electromagnetic interference noise of the Buck converter is reduced. A new chaotic system is designed by changing a nonlinear term of a classical Lorenz system, a chaotic spread spectrum circuit is designed, a PWM signal generated by the chaotic circuit serves as a spread spectrum signal, a switching tube driving signal of a Buck converter is controlled, and chaotic spread spectrum EMI noise suppression is achieved. According to the Buck converter, the noise peak value of the Buck converter at the switching frequency and the frequency doubling position can be reduced, so that the conduction electromagnetic interference of the Buck converter is reduced, the circuit is easy to build, and the EMI reduction effect is obvious.