1295 results about "Down conversion" patented technology

The invention discloses an adaptive modulation anti-multipath unmanned aerial vehicle swarm communication method and system based on MIMO-OFDM, and relates to the technical field of wireless communication, and the method comprises the steps: receiving a down-conversion baseband; synchronization and compensation are carried out; removing a cyclic prefix and carrying out fast Fourier transform; estimating a channel and noise on the training and pilot frequency, and correcting a common phase; performing frequency domain equalization and soft decision, forward error correction and cyclic redundancy check according to the estimation to obtain a control parameter, decoding a payload according to the control parameter, and performing statistics to form a link quality indication; modulating coding, bandwidth and spatial mode, configuring mapping, power and weight, and packaging physical layer protocol data; carrier sensing conflict avoiding sending, confirmation and retry are adopted to generate media access statistics; and the routing selects the next-hop multi-hop forwarding according to the transmission quality, and performs end-to-end statistics and recharge. Through cooperation of hierarchical synchronization and phase correction with cyclic prefix and FFT, crosstalk is suppressed, channel noise scale optimization soft decision is robust, data decoupling is controlled, and end-to-end availability is improved through multi-hop self-healing recharge.

The invention discloses an RFSOC-based FAST core array distributed collaborative observation and data fusion method and system, and the method comprises the steps: S1, system initialization: a master node RFSOC generates a global clock, achieves the phase synchronization of multiple board cards through an SYSREF differential signal, and completes the calibration of a three-stage clock tree; s2, signal acquisition and preprocessing: directly sampling a 3-8GHz radio frequency signal through an ADC (Analog to Digital Converter), and performing digital down-conversion to obtain a baseband signal; s3, intelligent resource scheduling: identifying a signal type based on an ESN (Echo State Neural Network), and dynamically allocating FPGA logic resources through an improved ant colony algorithm; s4, heterogeneous calculation acceleration: executing a 128-channel digital beam forming pipeline on the FPGA; s5, cross-domain data fusion; s6, collaborative observation planning; and S7, outputting data. The method is suitable for multi-beam synthesis, cross-region joint observation and mass data real-time processing scenes, and provides key technical support for solving the frontier scientific problems such as rapid radio storm origin and black hole activity monitoring.

The invention belongs to the technical field of low-orbit satellite communication, and discloses a satellite system for jointly improving measurement and control data transmission and communication application efficiency. A control unit is responsible for completing satellite calendar attitude calculation of satellite broadcast, analyzing a satellite working mode switching instruction according to ground station information stored by a storage unit, and then sending the instruction to each module unit; the two baseband processing units both support on-orbit reconstruction and loading, wherein the baseband processing unit A is used for completing measurement and control signal processing or user wide beam access signal processing; the baseband processing unit B is used for completing communication service signal processing or data transmission signal processing; the two up-conversion units respectively carry out up-conversion processing on a service link signal and a measurement and control link signal in the signal processing module, and the two down-conversion units respectively receive signals of the phased array transceiver antenna and the wide beam transceiver antenna and complete down-conversion processing. The measurement and control link can support a satellite measurement and control function and a communication wide beam access function in a time-sharing manner.

The invention discloses a frequency hopping signal real-time detection method and system based on FPGA + DSP. The system comprises a time frequency analysis module, a data communication module and a frequency hopping signal detection module. The method comprises the following steps: a time frequency analysis module performs analog-to-digital conversion and digital down-conversion on an intermediate frequency signal received from a radio frequency end, and performs short-time Fourier transform on a zero intermediate frequency signal by adopting a four-pipeline processing mode; the data communication module transmits the frequency spectrum information from the FPGA to the DSP through an SRIO protocol; the frequency hopping signal detection module calculates a dynamic threshold of a current frame signal according to the received frequency spectrum information, and completes preliminary detection of the signal according to a threshold value; and carrying out binarization processing and connected domain marking on the detected frequency spectrum, screening non-frequency hopping signals according to time-frequency information of a connected domain, and packaging and uploading parameter information of the detected frequency hopping signals to an upper computer. The method is simple in algorithm, low in hardware resource requirement and high in detection efficiency, and the feasibility of engineering implementation is improved.

The invention relates to the technical field of ground resistance detection, in particular to a single-core cable ground resistance detection method capable of resisting strong power frequency interference. High-frequency signals are injected in a non-contact mode through a coupling type capacitor clamp, background voltage and current signals are collected firstly, and injection frequency far away from power frequency and harmonic waves is selected through Fourier analysis; cancelling background noise by adopting a normalized least mean square adaptive filter to generate an enhanced signal; the signal is down-converted to a base band through digital quadrature demodulation, a Kalman filter estimates the amplitude and the phase in real time, and the state and noise parameters are periodically calibrated through a compressed sensing algorithm; and finally, loop impedance is calculated according to the voltage and current amplitudes and the phase difference to obtain grounding resistance. The method has the advantages of being non-contact, high in safety, strong in anti-interference capability, high in measurement precision and the like, and is suitable for monitoring the grounding state of the cable in a complex electromagnetic environment.

This disclosure describes an auto-calibration of mixers in a quantum orchestration platform. Predistortion is computed according to an RF signal that is downconverted with a local oscillator tone that is offset from an upconverter tone. Three tones present in the original RF signal are distinguished and used to construct a cost function. The minimization of the cost function is used to cancel an unwanted LO leakage and an image tone. Because the quantum orchestration platform generates both the unconverted IQ signals and the cost function for their optimization, the optimization can be performed in real time inside a single device without the need to communicate with external devices. This allows for the optimization of single sideband upconverted signals in a fraction of the time it typically takes using distributed systems employing separate waveform generators and spectrum analyzers.

The invention relates to the technical field of signal analysis, in particular to a GNSS (Global Navigation Satellite System) detection method and system based on machine learning, and the method comprises the steps: receiving a navigation radio-frequency signal containing reality and deception, and carrying out the down-conversion of an RF (Radio Frequency) front end to obtain intermediate-frequency data; gNSS signal capture is completed by searching correlation peaks in frequency and code phases based on intermediate frequency data; in the capturing stage, a motion state, a correlation peak number, a noise value, capturing parameters and peak + / -1 chip sampling features are extracted and input into a machine learning classification model to judge whether cheating exists or not; if so, separating the deception signal from the real signal, and respectively sending the deception signal and the real signal into independent tracking channels; measuring an array element carrier relative phase by an array antenna, establishing a phase center model, and correcting to obtain an effective phase center and a differential baseline; according to the method, a deception azimuth angle and a pitch angle are obtained, a beam weight is calculated, a deception direction is subjected to null setting, a real direction is subjected to main lobe protection, and a weight value is fed back in real time to improve a signal carrier-to-noise ratio and locking stability. According to the invention, the problem that the existing commercial GNSS signal is low in power and easy to be interfered by deception is solved.

The invention relates to the technical field of signal processing, in particular to an intelligent blind equalization method and device for large-scale carrier frequency deviation, and the method comprises the steps: carrying out the down-conversion of an original received signal of a preset modulation type, so as to sample an original complex sampling point sequence with large-scale carrier frequency deviation; performing local information exchange, parameter correction and splicing on the original complex sampling point sequence to obtain a compensated complex sampling point sequence; performing pre-extraction and channel amplification on the compensated complex sampling point sequence to obtain pre-extraction features containing implicit channel state information, and further extracting spatial information and time sequence dependence in the pre-extraction features to balance multipath fading of the original complex sampling point sequence and obtain balanced output; and demodulating the original bit information of the original complex sampling point sequence according to the balanced output. Therefore, the problem that a blind equalization method in the related technology cannot effectively adapt to a time-varying multipath channel and a scene with large-scale carrier frequency deviation is solved.

A frequency offset estimation method for a satellite VDES system, characterized in that it includes the following steps: step 1, down-converting a carrier-containing signal output by an AD to move the signal to a baseband; step 2, performing CIC down-sampling processing on the down-converted signal to reduce the data rate to 4 times the symbol rate; step 3: performing frame synchronization processing on the CIC down-sampled signal to find the position of the frame header; step 4: performing coarse frequency offset estimation and compensation on the signal after the frame synchronization processing; step 5: performing Mpart fine frequency offset estimation on the signal after the coarse frequency offset compensation.

The invention discloses an independent double-single-side-band direct detection system based on geometric shaping and digital chaotic encryption, and belongs to the field of terahertz communication. According to the detection system, an external cavity laser ECL of a sending end generates continuous optical carriers, the continuous optical carriers are input into an I / Q modulator, a TX-DSP module generates two independent vector radio frequency signals of GS-QPSK and GS-NQAM through geometric shaping and a three-dimensional multi-vortex chaos system technology, the I / Q modulator is driven to modulate the input optical carriers, and the optical carriers are transmitted to a receiver. After being amplified, the terahertz signals are input into a one-way carrier photoelectric detector for frequency beating to obtain independent double-sideband terahertz signals, the independent double-sideband terahertz signals are input into a frequency mixer of a receiving end for frequency mixing with generated local oscillation signals, down-conversion of the signals is achieved, and fundamental frequency signals are obtained; and then the data are input to an RX-DSP module, normalization, down-sampling, signal separation, de-mapping, symbol-level and bit-level decryption and other operations are carried out, and finally two paths of original data are obtained to solve the bit error rate. According to the invention, the system communication capacity is improved, and the security of independent double-sideband signal transmission is improved.

The invention discloses a differential signal synthesis circuit of a double-IQ mixer, which belongs to the technical field of radio frequency microwave testing and comprises two single-ended IQ mixing modules, a 180-degree phase shift module and an in-phase combination module or a power division module. The single-ended IQ frequency mixing module is used for up-converting the single-ended IQ baseband signal to radio frequency or down-converting the radio frequency signal to the single-ended IQ baseband signal; the 180-degree phase shift module is used for converting an input signal into two paths of signals with a phase difference of 180 degrees; and the power division module is used for converting the radio frequency input signal into two paths of signals with the phase difference of 0 degree. According to the invention, the IQ mixer with a differential structure is constructed, so that the microwave band of the IQ mixer is comprehensively improved in the index aspects of local oscillator leakage, even-order component suppression, common-mode interference suppression, signal-to-noise ratio and the like; according to the invention, single-ended IQ mixers with various types and complete frequency bands can be constructed into a differential structure form, and signal indexes in numerous application scenes are improved.

The invention discloses a broadband digital beam forming method based on a Farrow filter, and the method comprises the following steps: carrying out the DDC down-conversion and phase shift processing of a signal after the analog-to-digital conversion of a broadband signal is completed through an ADC; calculating the delay inequality of each array element signal relative to a reference array element, and decomposing the delay inequality into an integer sampling period and a fractional delay component; a fourth-order Lagrange type Farrow filter oriented to FPGA / DSP optimization is adopted to carry out fractional time delay compensation, and coefficients of the Farrow filter are dynamically adjusted through a polynomial expansion formula; and finally, performing complex weighted synthesis on each channel filtering signal to generate a directional wave beam. According to the method, high-precision fractional delay adjustment is achieved, the Farrow filter is adopted, the tedious process of recalculating coefficients can be omitted, only the P value is changed, and high-precision beam direction control can be achieved under the condition of low calculation amount.

The invention specifically relates to a radar system for realizing communication and inductance integration, and the system comprises a field programmable gate array signal processing assembly which is used for generating an initial local oscillation signal and a customized initial emission waveform according to a control instruction of an upper computer, and outputting the initial emission waveform to an emission assembly, outputting the initial local oscillation signal to a local oscillation system component; the transmitting component is used for modulating a self-defined initial transmitting waveform, then generating a target transmitting signal and transmitting the target transmitting signal; the receiving component is used for receiving the reflected signal and modulating the reflected signal; the local oscillation system component is used for performing frequency conversion processing on the initial local oscillation signal and outputting a first LO signal subjected to up-conversion processing to the transmitting component, so that the transmitting component modulates the first LO signal and a customized initial transmitting waveform; and outputting the second LO signal subjected to down-conversion processing to a receiving component, so that the receiving component modulates the second LO signal and the reflected signal.

The invention discloses a broadband noise generation method based on predistortion calibration, and relates to the technical field of communication, and the method comprises the steps: S1, setting a flatness threshold value, and screening out an original noise signal needing to be calibrated; s2, generating an inverse filter coefficient and a filter suppression coefficient for the original noise signal; s3, performing frequency response compensation by using an inverse filter coefficient, performing band-pass filtering by using a filter suppression coefficient, performing down-conversion to a baseband, and reducing a sampling rate; and S4, comparing the processed signal with a flatness threshold value, and if the processed signal does not exceed the flatness threshold value, indicating that signal calibration is completed, otherwise, entering calibration again. By introducing a pre-distortion calibration mechanism, the inverse filter coefficient is calculated in real time to compensate the system frequency response, the spectrum distortion caused by a fixed filter is effectively eliminated, and the method has the advantages of realizing dynamic and adaptive filter adjustment, effectively reducing the manual participation frequency and improving the continuous operation capability and the test efficiency of the system.

The invention discloses a communication-detection integrated sonar signal design method and device based on multi-pulse composite modulation, and the method comprises the steps: dividing a total frame period into a detection sub-frame and a communication sub-frame, enabling the detection sub-frame to achieve the high-resolution distance measurement through employing a bidirectional linear frequency modulation (BILFM) signal, a communication sub-frame adopts a multi-frequency multi-phase composite modulation (MTPM) signal to realize high-bit-rate data transmission; after band filtering, orthogonal demodulation, low-pass filtering and down-sampling preprocessing are carried out on detection sub-frame echoes, distance and speed information is extracted by adopting fast-time low-sampling two-dimensional fast Fourier transform (2D-FFT), unambiguous Doppler frequency is recovered by utilizing the Chinese remainder theorem (CRT), and accurate speed measurement of long-distance and high-speed targets is realized; a communication subframe receiving signal is subjected to IQ demodulation after down-conversion, Costas loop carrier synchronization and matched filtering, and multi-frequency multi-phase coded data are extracted. According to the method, the time-frequency collaborative design of detection and communication is realized, the distance resolution and the speed measurement range are considered, and the signal bandwidth utilization rate and the underwater information transmission reliability are remarkably improved while the system complexity is kept low. The device comprises a processor and a memory, and an executable program for implementing the method is stored in the memory. The technology can be widely applied to the fields of unmanned underwater vehicles, ocean monitoring, underwater sensing networks and the like.

The invention relates to a method for realizing multi-channel ADC (Analog to Digital Converter) data synchronization processing based on an FPGA (Field Programmable Gate Array), which comprises the following steps that: the FPGA receives a clock frequency generated by an external clock generator and takes the clock frequency as a working clock of the FPGA; a plurality of groups of same-frequency clocks and same-phase clocks are generated in the FPGA and are respectively used as working clocks of the ADC chips; the FPGA receives sampling data of each ADC, an enable signal is set, and when the enable signal is effective, digital down-conversion, decimation filtering and FIR filtering are carried out on each sampling data; and after FIR filtering is completed, another enable signal ENend is generated, and data are further stored or transmitted to an upper computer. According to the method and the device for realizing the multi-channel ADC data synchronous processing based on the FPGA, the processor and the computer readable storage medium thereof, synchronous start and stop of the processing flow are controlled through the enable signals ENstart and ENend, synchronous processing of the multi-channel ADC data is ensured, accuracy and effectiveness are improved, and the method and the device have a wide application range.

The invention discloses a signal receiving method and device, which can reduce the peak power of a signal input to an analog-to-digital converter (ADC), thereby reducing quantization noise and improving signal receiving performance. The method comprises the following steps: receiving a first signal by a receiving device, performing down-conversion on the first signal to obtain a second signal, determining a third signal according to the second signal, sampling the third signal, and determining a target signal. Wherein the first signal comprises a target signal, and the target signal adopts comb mapping, that is, the target signal occupies one subcarrier in every M continuous subcarriers. The third signal comprises superposition of K delay signals of the second signal, the delay time associated with the kth delay signal in the K delay signals is # imgabs0 #, T is the time length of the first signal, k = 1, 2,..., K, delta is greater than or equal to 0, M is a positive integer greater than 1, and K is a positive integer greater than or equal to M.

The invention provides a satellite communication system with multi-mode capability and a communication method, and belongs to the technical field of satellite communication. A signal processing module of the system comprises a load control unit and a baseband processing unit, the load control unit is responsible for beam correlation calculation, transmission rate control, antenna channel power-on and power-off control and the like, the baseband processing unit is used for processing uplink and downlink signals, and the downlink supports multiple modes. The frequency conversion processing module is provided with an upper frequency conversion channel and a lower frequency conversion channel which respectively process transmitted and received signals. And the wide-beam receiving antenna is responsible for receiving uplink data. The phased array transmitting antenna is responsible for transmitting downlink data, is high in gain and fast in pointing adjustment, and supports multiple modes. According to the communication method, satellite transmitting and receiving are started by default, and transmitting serves as a beacon to assist a user in capturing. According to the invention, the working modes can be flexibly switched, the telemetering downloading capability and the information broadcasting efficiency are improved, and diversified communication requirements are met.

The invention discloses a photon device and method for simultaneously measuring Doppler frequency shift and an angle of arrival, and belongs to the technical field of microwave photon-assisted radars. The device is configured to enable a transmitting signal and a reference signal to enter a first dual-parallel Mach-Zehnder modulator working in a carrier suppression single sideband modulation mode after being combined so as to generate two positive first-order sideband signals, and then the two positive first-order sideband signals enter a second dual-parallel Mach-Zehnder modulator and are modulated by an echo signal; and a modulation signal output from the second dual-parallel Mach-Zehnder modulator enters a photoelectric detector for photoelectric conversion to generate a down-conversion signal. Comparing the frequency of the down-conversion signal with the frequency of the reference signal by using an electric spectrum analyzer to obtain the magnitude and direction of Doppler frequency shift; the arrival angle of the target can be obtained by monitoring the power of the frequency conversion signal. Measurement of Doppler frequency shift and the angle of arrival can be completed only by using the photoelectric detector with the bandwidth lower than the frequency of the transmitted signal, and the requirement for the bandwidth of the photoelectric detector is lowered.

The invention relates to a low-orbit satellite short burst signal high-precision capturing method and device, equipment and a medium. The method comprises the following steps: sequentially carrying out digital down-conversion and L-time signal pseudo code rate down-sampling on a low earth orbit satellite short burst signal sequence sampled by an ADC (Analog to Digital Converter) to obtain a down-sampled signal sequence; performing pre-accumulation processing on the down-sampling signals of every adjacent L points in the down-sampling signal sequence, and performing coarse capture on the pre-accumulated signal sequence by adopting a PMF-FFT algorithm to obtain a coarse pseudo code phase and a coarse frequency offset value; and performing serial code phase search on the down-sampling signal sequence based on the coarse pseudo code phase and the coarse frequency offset value, optimizing to obtain a fine pseudo code phase, and optimizing the estimation precision of the coarse frequency offset value according to the fine pseudo code phase and a frequency offset estimation algorithm based on a phase relation to obtain a fine frequency offset value. By adopting the method, the acquisition precision and speed of the short burst signal of the low-orbit satellite can be improved.

A multi-channel analog-digital converter (ADC) subsystem for test device such as a spectrum analyzer may include multiple multi-channel ADCs to receive down-converted signals and convert the received signals to digital output signals, a field programmable gate array (FPGA) to select one or more ADCs based on a frequency, a bandwidth, and / or a signal type of each received signal and a characteristic of each ADC, and an ADC sample clock to provide a clock signal to the selected ADCs. Characteristics of the ADCs may include a resolution, a signal-to-noise-and-distortion ratio (SINAD), an effective number of bits (ENOB), a signal-to-noise ratio (SNR), a total harmonic distortion (THD), a total harmonic distortion plus noise (THD+N), and / or a spurious free dynamic range (SFDR).

The invention discloses a self-adaptive CPFSK multi-symbol incoherent demodulation method, and belongs to the field of communication signal processing. The implementation method comprises the following steps: initializing a receiving signal and the length of an observation window; performing orthogonal down-conversion on the received signal to obtain a baseband received signal; constructing a local template sequence according to the length of the observation window, and performing baseband modulation to generate a local baseband template signal; according to the baseband receiving signal and a local baseband template signal, constructing an incoherent judgment statistic, and selecting a candidate sequence; classifying the candidate sequences into credible sequences and uncredible sequences by comparing the judgment of the candidate sequences before and after about the same symbol; taking an intermediate symbol of the credible sequence as an incoherent judgment result, and adding one to the position of the symbol to be judged; for an untrusted sequence, the length of an observation window is expanded, a candidate sequence is selected again, an intermediate symbol is used as a new incoherent judgment result, the position of a symbol to be judged is increased by one, iteration is repeated, and self-adaptive multi-symbol incoherent demodulation is achieved.

The invention relates to the technical field of radio frequency, in particular to a radio frequency conversion assembly, and the assembly comprises a baseband processing unit which employs a millimeter wave SoC chip and is used for generating and processing an initial transmitting signal of 79-81GHz and an initial receiving signal of 79-81GHz; the frequency conversion unit comprises an up-conversion subunit and a down-conversion subunit, and the local oscillation synthesis unit is used for generating and providing a local oscillation signal with a fixed frequency; the mode switching and processing system is used for selectively performing down-conversion processing on the echo signal or a target radio frequency signal from an external non-cooperative irradiation source in two working modes and then transmitting the echo signal or the target radio frequency signal to the baseband processing unit; the working mode comprises an active mode and a passive mode.

The invention discloses a method and a device for processing VHF (very high frequency) and UHF (ultra high frequency) navigation signals based on ZYNQ, and relates to the technical field of signal processing, and the method and the device are characterized in that a single ZYNQ chip is used for replacing an FPGA (field programmable gate array) + DSP (digital signal processor) dual-chip framework of a digital processing part of a traditional aviation navigation signal receiver, so that the system integration level is increased, the design is more compact, the circuit design is simpler, and the system reliability is improved. Lightweight design of airborne equipment is facilitated; besides, by means of the strong processing performance of the PL part of the ZYNQ chip and the high-speed analog-to-digital conversion chip (ADC) which develops rapidly, receiving of VHF and UHF navigation signals can be achieved through the radio frequency direct sampling technology, complete digitization of analog down-conversion is achieved, and the advantages are that the problems of leakage and frequency offset of an analog local oscillator and generation of more harmonic waves and stray can be solved. And the electromagnetic interference of equipment is obviously reduced.

The invention discloses a non-standard electromagnetic target detection and smart interference integrated system based on a ZYNQ architecture in the technical field of electronic countermeasure and communication systems, and the system comprises an antenna unit which is used for receiving and transmitting electromagnetic signals of a wide frequency band; the gain module is used for amplifying the received and transmitted signals and improving the signal quality and the detection sensitivity; the radio frequency front end is used for completing up-down frequency conversion and analog-to-digital conversion of signals and transmitting and receiving operation of radio frequency signals and providing necessary signal conversion and processing functions for the system; the PC end is used for issuing a control instruction and adjusting the gain of the system so as to realize amplification and flexible adjustment of the signal; the FPGA signal processing unit is used for completing signal generation, receiving and processing and subsequent signal analysis and interference algorithm execution based on an FPGA platform, the detection precision and the processing speed of the system are remarkably improved, a non-standard electromagnetic target in a complex electromagnetic environment can be efficiently recognized and dealt with, and interference response is flexibly carried out.

The invention relates to the field of satellite ground station electromagnetic environment monitoring, in particular to a full-band satellite ground station electromagnetic environment monitoring system. Comprising a monitoring and direction-finding subsystem and an information processing subsystem, and an omnidirectional real-time monitoring device and a directional high-sensitivity monitoring device receive interference signals through corresponding monitoring antennas and direction-finding antennas and send the received interference signals to corresponding radio frequency receivers. The radio frequency receiver antenna processes the received signal, outputs an intermediate frequency signal, and sends the intermediate frequency signal to a corresponding signal processing unit; the signal processing unit is used for sampling an input signal, then carrying out down-conversion, filtering and extraction preprocessing operation according to a specified frequency, carrying out analysis and monitoring direction finding on preprocessed data, and transmitting monitoring direction finding data to the information processing subsystem; and the information processing subsystem receives monitoring results of the ground stations and performs fusion statistical processing. The method is suitable for satellite ground station electromagnetic environment monitoring.

The invention relates to a time domain broadband adaptive beam forming method and system based on Chebyshev weighting, and belongs to the field of array signal processing. Aiming at the technical problems of poor real-time performance and high sidelobe of the existing broadband beam forming, the method comprises the following steps of: dividing a received broadband signal into a plurality of sub-bands, obtaining an optimal weight vector for each sub-band by adopting a minimum linear constraint iterative algorithm after down-conversion, constructing an expected response of an FIR filter according to each weight, obtaining a filter coefficient through L2 norm convex optimization, and finally obtaining a high sidelobe beam according to the expected response of the FIR filter. And performing time domain weighting on each array element signal by using a filter bank, and outputting a directional beam. According to the method, the calculated amount is low, a main lobe and interference null can be formed in real time in a broadband, and a certain side lobe height is kept.

The invention provides an orthogonal down-conversion mixer, which comprises a first signal input port, a signal processing module and a mixing module, and is characterized in that a radio frequency signal is converted into a differential radio frequency signal through the first signal input port, and phase shift, amplification and impedance matching are performed on an initial local oscillator signal through the signal processing module; a first local oscillator signal and a second local oscillator signal are used for receiving a differential radio frequency signal, two local oscillator signals with orthogonal phases are obtained, the differential radio frequency signal is amplified through a pseudo-differential structure in a frequency mixing module, and frequency mixing is performed on the first local oscillator signal, the second local oscillator signal and the amplified differential radio frequency signal to obtain two target intermediate frequency signals. According to the orthogonal down-conversion mixer provided by the invention, the differential radio frequency signal is amplified through the pseudo-differential structure, the noise coefficient and power consumption of the mixer are reduced, the mixing speed is increased through the two local oscillator signals, and the noise coefficient of the mixer is further reduced.

The invention discloses a multi-satellite direct positioning method based on CUDA (Compute Unified Device Architecture) parallel calculation, relates to the field of space-based electromagnetic signal positioning, and aims to be suitable for large-range and high-precision positioning of low-signal-to-noise-ratio signals. According to the technical key points, a positioning area is determined in a satellite coverage range according to prior information, and grid points are divided on the surface of the earth; two or more satellites with time-frequency synchronization obtain observed quantities of signals emitted by the same ground radiation source, a first signal model of the multiple observed quantities is constructed, and down-conversion is carried out on the first signal to obtain a second signal; constructing a cost function by using signal characteristics (such as time difference of arrival, frequency difference of arrival and the like) in a radiation source signal received by a satellite; a cost function corresponding to each grid point is subjected to multi-core parallel computing through the GPU; and summarizing results, and searching the maximum value of the cost function to determine the estimated position of the ground radiation source. According to the multi-satellite direct positioning method based on the CUDA, the characteristic that parallel calculation can be carried out when cost function grid searching optimization is carried out in direct positioning is utilized, calculation is directly carried out on satellites, satellite-ground data transmission is omitted, the positioning time is shortened by utilizing the independence of searching calculation among grids, and the real-time performance of a positioning system is guaranteed.

The utility model discloses a vehicle-mounted quick-charging USB charging module, and belongs to the technical field of charging modules. The technical problems that no input protection exists in the charging process, and when positive and negative electrodes of an input end are reversely connected, a fast charging module is damaged are solved. According to the technical scheme, the power supply comprises a power supply input end, a rectification filtering module, a step-down conversion module and an output interface, the power supply input end is used for obtaining external alternating current and inputting the external alternating current to the rectification filtering module, the rectification filtering module is used for outputting first direct current, and the step-down conversion module receives the first direct current for power supply; the step-down conversion module is connected with the output interface for providing charging power; the charging module has the advantages that the positive electrode and the negative electrode do not need to be considered when the charging module is installed, the installation reliability of assembly connection is improved, and the charging module is provided with multiple interfaces and is convenient to adapt.