35results about How to "Improve distance resolution" patented technology

The invention discloses a pulse compression method for the field of linear frequency modulation signals. The method comprises the following steps: the orthogonal demodulation is implemented for the linear frequency modulation signals in the time domain; the low-pass filtering is implemented for the orthogonally demodulated linear frequency modulation signals in the time domain; the Fourier transform and the frequency band transfer are sequentially implemented for the low-pass filtered linear frequency modulation signals in the time domain to obtain linear frequency modulation signals in the frequency domain; the Fourier transform and the frequency band transfer are sequentially implemented for matched filtering signals in the time domain to obtain matched filtering signals in the frequency domain; the matched filtering signals in the time domain are converted to the matched filtering signals in the frequency domain; the complex conjugate multiplication is implemented for the linear frequency modulation signals in the frequency domain and the matched filtering signals in the frequency domain to obtain pulse compression signals in the frequency domain; and the Fourier inversion is implemented for the pulse compression signals in the frequency domain to obtain pulse compression signals in the time domain. The pulse compression method of the invention can improve the range resolution, reduce the loss of signal-to-noise ratio, and modify the image quality.

The invention relates to a method and a device for testing piezoelectric coefficient with near field electron scanning microscope according to converse piezoelectric effect. The invention comprises: making sample for testing and measuring the dielectric constant epsilon, setting distance between the microscope probes and sample and then: (1) connecting the output terminal of the signal generator with the sample electrode, and separating one terminal to connect with the reference signal input terminal of phase-locking amplifier to adding cycle modulation signal on the sample electrode; (2) connecting the input of the phase-locking amplifier with the frequency signal output terminal of the microscope controller, and the output terminal being connected to the data collection and process system, a cycle modulation signal v in the microscope signal being made by cyclomorphosis of piezoelectricity on probe sample; (3) calculating piezoelectric coefficient according to formula dij=-1 / (5.80b2-9.09b+3.77).gL / ASf0l.nu / V.

The invention discloses a multi-band ultra-wideband imaging processing method for radar near-field measurement. The main steps are as follows: first, filter-backprojection (MIMO-backprojection) suitable for multiple-input multiple-output (MIMO) radar near-field imaging processing is adopted. FBP) algorithm, image reconstruction of MIMO radar imaging data in multiple bands, and automatically complete channel equalization, pattern correction, propagation attenuation compensation and spherical wavefront correction under each band, and obtain low resolution of each band complex image; secondly, through two-dimensional fast Fourier transform (2‑D FFT), the complex image of each band is transformed into the corresponding data domain, and resampled along the fan ring to obtain the fan ring domain data corresponding to each band image ; thirdly, fuse the obtained multi-band fan ring domain imaging data in an appropriate way to obtain full-band MIMO ultra-wideband imaging data; finally, use the traditional FBP imaging algorithm to reconstruct the image of the fused full-band data, thus Obtain full-band high-resolution images.

The invention provides an active imaging readout circuit working on a linear mode APD (Avalanche Photo Diode) array. The circuit is provided with a probe, a high voltage protective circuit, an injecting circuit, a comparator and a voltage retaining circuit; the output of the probe is connected with the input of the high voltage protective circuit; the output of the high voltage protective circuit is connected with the input of the injecting circuit; the output of the injecting circuit is connected with the input of the comparator circuit; the output of the comparator circuit is connected with the input of the high voltage retaining circuit; the output of the voltage protective circuit is connected with the injecting circuit and a subsequent processing buffer circuit; and the output of the injecting circuit is further connected with the subsequent processing buffer circuit.

The embodiment of the invention discloses a laser radar system. The laser radar system comprises a light source module, a modulation light module, a transmitting-receiving module, a detection module and a signal processing module, wherein double-wavelength laser beams are subjected to linear modulation through a modulation light module and are converted into double-frequency linear frequency modulation continuous wave laser beams; one laser beam is used as a local oscillation light beam and the other laser beam is used as signal light which has mutual effect with a detection target; the signal light scatters an echo signal through the detection target; the local oscillation light beam and the echo signal are subjected to coherent beat frequency, so as to obtain double-wavelength Doppler frequency shift difference value information. The laser radar system disclosed by the invention adopts double-wavelength linear frequency modulation laser so that influences, caused by non-linear linear frequency modulation and an atmospheric turbulence effect, on a speed measuring resolution ratio are extremely reduced; distance measurement and speed measurement are carried out on the detection target at the same time; the laser radar system has the advantages of high detection precision, electromagnetic interference resistance, no distance dead zones and the like.

The invention discloses a high repetition frequency velocity measurement method based on frequency stepping LFMCW, which obtains a larger non-fuzzy velocity measurement range by using high repetitionfrequency, and simultaneously splices signals by using the characteristics of frequency stepping LFMCW signals to obtain higher distance resolution; and compared with the traditional high-distance resolution, low-ambiguity speed measurement range or low-distance resolution and high-ambiguity speed measurement range, the high repetition frequency velocity measurement method has more application advantages.

The invention discloses a matching compression device for linear frequency modulation signals and a matching compression method. The matching compression device comprises a linear frequency modulation signal source (1), a first power distributor (2), a digital control oscillator (3), a second power distributor (4), a 90-degree phase shifter (5), a first frequency mixer (6), a second frequency mixer (7), a first low-pass filter (8), a second low-pass filter (9), a first data acquirer (10), a second data acquirer (11), a matching filter (12) and a computer (13). Compared with pulse compression devices and compression directions in the prior art, the matching compression device and the matching compression method disclosed in the invention can improve the range resolution, reduce the signal-to-noise-ratio loss, and modify the image quality. The matching compression device and the matching compression method disclosed in the invention can be used for signal processing of radar and earthquake detecting systems.

The invention provides a method and device for generating a pulse compression coefficient of a target detection radar system. The method includes: an FPGA main control module calculates configuration parameters and inputs them into a direct frequency synthesizer; the direct frequency synthesizer generates a chirp signal required by the radar system, and send it to the radio frequency front-end module; the transmitting channel of the radio frequency front-end module up-converts the chirp signal to the radio frequency band, and loops back to the receiving channel of the radio frequency front-end module through the radio frequency cable, and the receiving channel down-converts the signal of the radio frequency band Convert the frequency to the intermediate frequency and send it to the analog-to-digital converter; the analog-to-digital converter transmits the data of the loopback signal to the FPGA main control module; the data analysis module receives the loopback DDS data exported by the FPGA main control module, and runs the pulse compression coefficient optimization method , to calculate the optimal pulse compression coefficient. According to the solution of the invention, the pulse compression performance of the radar system can be improved, and a higher radar distance resolution can be obtained.