9 results about "Local spread" patented technology

The invention discloses a GNSS multipath parameter estimation method based on multi-correlator output, and belongs to the field of satellite signal multipath resistance. The invention discloses a GNSS multipath signal parameter estimation method, and aims to provide a novel GNSS multipath signal parameter estimation method which comprises the following steps: performing correlation operation on a local spreading code and a received signal through a GNSS correlator, and mining internal correlation between a correlator interval and a multipath error based on a correlation output result of a composite signal; the method comprises the following steps: acquiring multipath error data of multiple groups of correlators to construct a relation curve by combining an analytical formula of correlator spacing and multipath errors, reversely deducing multipath parameters by solving coordinates of turning points of the curve, and finally realizing accurate estimation of the multipath parameters. According to the method, the time delay, phase and amplitude parameters of the short multipath can be accurately identified, and the capability bottleneck of a traditional algorithm in the aspects of short multipath suppression and estimation is effectively broken.

A dynamic code loop phase discrimination method comprises: S1, obtaining a segment of received spread spectrum data required by a current epoch, and performing carrier frequency and phase compensation on the received spread spectrum data to obtain current epoch loop input data; S2, a control unit selects different code loop phase discrimination modes according to a scene or a loop state; S3, a local code generation unit generates multiple local spread spectrum codes; S4, a correlation unit completes multiple correlations of data and local spread spectrum codes, and a phase discrimination unit obtains a current epoch code loop phase discrimination value based on a correlation result; S5, a dynamic filtering unit dynamically adjusts filtering coefficients based on multiple correlation integrals of the correlation unit, dynamically filters the code loop phase discrimination value, and outputs a code phase; S6, a feedback unit converts the code phase into an offset sampling point and feeds back the offset sampling point to control selection of next epoch received spread spectrum data. The method can accurately perform code loop phase discrimination and accelerate code loop convergence in a multipath and non-multipath scene, improve reliability of signal tracking, and improve system reception performance.

The spreader system includes two spreader rotors configured to rotate about upright rotation axes and to eject residue crop material centrally between the spreader rotors in a direction tangential to the spreader rotors. A deflector configuration including a first and second curved deflector blade is arranged to deflect crops ejected respectively by the first and second rotor, into respective first and second ejection directions. The deflector blades are pivotable about upright pivot axes, to adjust the ejection directions. A sensing arrangement is configured to sense local spreading patterns in a first and second adjustable sensing direction, measure the angular positions of the deflector blades by suitable measuring devices, and adjust the first and second sensing directions so as to correspond to the first and second ejection directions of the crop residue. A control unit is configured to receive signals representative of the local spreading patterns and of the angular positions.

The invention discloses a spreading code capturing method based on a dynamic threshold. The method comprises the following steps: S1, a capturing process control module realizes time sequence control and data flow control of a capturing process; s2, performing Doppler frequency offset elimination on orthogonal baseband data corresponding to the received BPSK direct spread spectrum modulation signal by a Doppler frequency offset elimination module; s3, storing the obtained data in a received signal storage module; s4, changing the phase of the local spreading code along with the capturing process to obtain a local spreading code sequence after phase shift; s5, PMF-FFT operation is executed, and orthogonal and in-phase signals and subscripts on the frequency domain are output; s6, calculating a maximum value and a corresponding subscript in each group of data by a peak value search module; s7, a capture judgment module judges whether the maximum value of the current group meets a judgment threshold or not, if yes, capture succeeds, and if not, the threshold is changed; and if the received signal spreading code is not captured at present, skipping to S2 and restarting the capturing process. According to the invention, the capturing success rate under the conditions of large dynamic Doppler frequency offset and low signal-to-noise ratio is realized.

The invention discloses a large-spread-spectrum-ratio direct spread signal capturing system suitable for a frequency hopping system, and relates to the field of communication systems. The system comprises a spreading code generation unit, a matched filter unit, a reading controller unit, a cache unit, an adder unit and a peak detection unit. Sliding matched filtering is carried out on a direct spread signal with the length of one hop and a local spread spectrum code, square addition is carried out on matching results of an I path and a Q path to obtain a matched filtering result, then a cache control unit is read to control a cache unit to output a matching result of an adjacent hop, and the matching result is added with a matched filtering result of a chip position corresponding to the current hop to obtain a matched filtering result. And finally, the peak value detection unit compares the matched filtering accumulation result of the same chip position of the multi-hop signal with a capture threshold value, and the capture is successful when the accumulation result exceeds the threshold value. The method can realize large-spread-spectrum-ratio direct spread signal acquisition of a frequency hopping system, and is suitable for a large-spread-spectrum-ratio hopping and spreading combined satellite communication system.

This invention relates to the field of communications and discloses a high-precision carrier frequency estimation device adapted to frequency hopping systems. The device includes a local spreading code generation unit, a data processing unit, a Fast Fourier Transform (FFT) calculation unit, and a carrier frequency estimation unit. The process includes: demodulating the 1-hop synchronization signal, downsampling the downsampled data and padding it with zeros, performing FFT calculation, performing peak search on the FFT calculation results, interpolating the FFT results, and estimating the signal carrier frequency. This invention provides high carrier frequency estimation accuracy and uses less data, making it suitable for frequency hopping systems. Furthermore, this invention uses fewer Fourier points, consumes less hardware resources, and has a smaller carrier frequency estimation delay.

The application discloses a GMSK direct spread signal double-code type frequency domain despreading method and device, and belongs to the technical field of wireless communication. In view of the problems of high hardware resource consumption and complex process caused by adopting conjugate sequence correlation and power difference judgment in the prior art, the application utilizes the frequency domain conjugate sequence of a local spread positive code to perform multi-frequency offset hypothesis parallel frequency domain correlation on a received signal in a capture stage, and determines a synchronous frequency offset and a code phase; after symbol segment frequency offset compensation, FFT transformation is performed in a despreading stage, frequency domain data are multiplied by the frequency domain conjugate sequence of the pre-stored local spread positive code and inverse code, and IFFT transformation is performed, and signed soft bits are output by directly comparing the peak values of the two correlation amplitudes. The application omits square operation and conjugate sequence generation, significantly reduces hardware resource consumption and processing delay, retains judgment confidence, and can share FFT / IFFT operation hardware in the capture and despreading stages, and further reduces implementation cost.

The embodiment of the application provides a binary offset carrier acquisition method and device, which can first perform carrier stripping on the received BOC signal to obtain the BOC signal after stripping the carrier; then acquires the ladder signal corresponding to the BOC signal, and generates the auxiliary sequence corresponding to the BOC signal based on the ladder signal and the local spreading code; then performs cross-correlation operation on the auxiliary sequence corresponding to the BOC signal and the BOC signal after stripping the carrier to obtain the first reconstructed signal of the BOC signal; and performs cross-correlation operation on the BOC signal after stripping the carrier and the local spreading code to obtain the second reconstructed signal of the BOC signal; further, the debiased signal of the BOC signal is determined based on the first reconstructed signal and the second reconstructed signal; finally, the debiased signal is acquired based on the preset acquisition threshold. Thus, the debiased processing of the BOC signal is better, and the ambiguity elimination effect and the acquisition effect of the BOC signal are improved.

The invention relates to the technical field of signal transmission, in particular to a spread spectrum tracking and capturing method and system based on a spread spectrum code and a medium, and mainly comprises the following steps: generating a local spread spectrum code through a local PN code generator; the method comprises the following steps: receiving an external spreading code in an external signal, performing down-conversion and down-sampling on the external spreading code, and outputting a first spreading sequence of IQ two paths of a code clock with the sampling rate being N times; and performing correlation operation on the first spread spectrum sequence and a second spread spectrum sequence of the local spread spectrum code, outputting a correlation operation result, performing FFT calculation on the correlation operation result to obtain coherent integration, judging whether the phase of the first spread spectrum sequence is aligned with the phase of the second spread spectrum sequence through the coherent integration, and if so, outputting to complete spread spectrum code capture.