200results about How to "Improve detection signal-to-noise ratio" patented technology

The invention discloses a high-dynamic weak-signal rapid capture method for a direct sequence spread spectrum system, belonging to the field of radio communication. Because a spread spectrum carrier has a chirp signal characteristic under the condition of high-dynamic motion (high-speed and high-acceleration), the high-dynamic weak-signal rapid capture method comprises the steps of: firstly, carrying out carrier Doppler frequency compensation by using a time frequency focusing characteristic of fractional order Fourier transform; secondly, carrying out incoherent accumulation on a spread frequency signal by using an order resolving capacity of the fractional order Fourier transform; and finally, carrying out capture judgment on the signal in an order Fourier domain by using a constant false alarm rate detection technology. According to the invention, the difficulty of incapability of long-time coherent accumulation under the high-dynamic condition in the traditional Fourier transform based rapid capture method is solved; and under the condition of high dynamicity and low signal to noise ratio, the signal to noise ratio is effectively increased and the signal capture time is shortened. In addition, a rapid algorithm exists in the invention and is easy to realize on the engineering in real time.

The invention relates to a diamond gyroscope with a color center, adopts a diamond material internally containing the high-concentration nitrogen-vacancy (NV-) color center as a sensitive element, realizes the control and the detection in the electronic energy level by using optical and microwave means and realizes the carrier angular velocity measurement. The diamond gyroscope with the color center has the advantages of room temperature operation, small volume, low cost and the like; compared with an existing gyroscope such as an MEMS (Micro Electro Mechanical System) and the like under same positioning, the diamond gyroscope with the color center is higher in theoretical sensitivity, and better in stability, has an important value on developing atomic spinning effect-based high-stability and small-volume solid-state atomic gyroscope, and is used for an inertial navigation and gesture measurement system in all fields in future, specially in the civil low-precision field.

The invention provides an LFMCW radar detection moving human body target method based on a human body model. The method comprises the steps that analog-to-digital conversion is carried out on an LFMCW radar echo beat signal; FFT processing is carried out on each PRI echo beat datum to acquire the LFMCW radar echo beat signal frequency domain data when a human body slowly moves, and rearranging is carried out in a slow time-distance domain two-dimensional plane; a Boulic human body walking model is constructed; according to the human body moving gait frequency and an initial phase range, a number of human body trunk moving models with different parameters are constructed on a gait frequency-initial phase two-dimensional plane; an LFMCW radar echo nonlinear phase compensation signal is reconstructed, and phase compensation is carried out on the rearranged data; FFT processing is carried out to acquire a four-dimensional space processing result; whether a target is in a distance unit is judged through constant false-alarm detection processing; and the information of distance, velocity and gait frequency of the target are acquired in the presence of the target. According to the invention, the signal-to-noise ratio of LFMCW radar detection is improved, and the human body target detection performance in strong ground clutter is improved.

The invention aims to provide a distributed optical fiber sensing device for simultaneously detecting Brillouin scattering and Raman scattering, which is characterized by comprising a narrow band light source, two optical couplers, a coded pulse optical modulator, an optical amplifier, three optical fibers, three photoelectric detectors, an electric decoder, an optical frequency shifter, an electronic processor, a light polarization controller and a wavelength division multiplexer. The distributed optical fiber sensing device has the advantages that the Brillouin scattering distributed optical fiber sensing and the Raman scattering distributed optical fiber sensing are simultaneously realized in the same device system; the Brillouin scattering is subjected to temperature compensation by the Raman scattering, so that double parameters of the temperature and the strain are simultaneously measured; and due to the utilization of a coding modulation and optical coherent detection technology, the detectable signal-to-noise ratio is improved, the sensing distance is lengthened and the detection accuracy is improved.

The invention discloses a detection system and a detection method of petroleum-type pollutants. The detection system comprises an emitting unit, a receiving unit, a reference unit and a signal processing unit. The emitting unit is used for emitting laser signals, and transmitted light signals and reflected light signals are outputted; an input terminal of the reference unit receives the transmitted light signals emitted from the emitting unit. An output terminal of the reference unit is connected to an input terminal of the signal processing unit. Reference signals outputted by the reference unit are transmitted to the signal receiving unit by the output terminal of the reference unit. A sample in a sample tank is excited by the reflected light signals, such that fluorescence signals are generated. The fluorescence signals are received by the receiving unit beside the sample tank, and are outputted to the signal processing unit by the receiving unit. The fluorescence signals are processed by the signal processing unit. The system and the method provided by the invention are based on laser-induced fluorescence detection principles. Emitted signals are modulated by using a modulation technology, such that the detection sensitivity of the system is high. With the method and the system, rapid, real-time, on-line and non-contact measuring upon water body petroleum-type pollutant fluorescence signals can be realized. The system and the method can be widely applied in water body environment monitoring.

The invention relates to a gas sensing technology and particularly provides a single-tube and coaxial photo-acoustic spectrum sound detector and a gas detection device adopting the sound detector, aiming at solving the technical problems that the acoustic coupling efficiency between an acoustic resonant cavity and a large tuning fork is relatively low when the large tuning fork is used as a sound detector in a current quartz enhanced photo-acoustic spectrum. The single-tube and coaxial photo-acoustic spectrum sound detector has the beneficial effects that firstly, a novel quartz enhanced photo-acoustic spectrum sound detector is designed, and a complete single-tube acoustic resonant cavity is inserted into an oscillation arm gap of a tuning fork type quartz crystal oscillator by virtue of the characteristics of the large oscillation arm gap of the novel tuning fork type quartz crystal oscillator; square holes are formed in the two sides of the single-tube acoustic resonant cavity, and acoustic waves push oscillation arms of the tuning fork type quartz crystal oscillator through the square holes so as to generate an electric signal; the acoustic coupling efficiency is greatly improved by single-tube and coaxial configuration, and the detection signal-to-noise ratio is improved; and secondly, a standing wave mode in the single-tube acoustic resonant cavity is relatively close to an acoustic standing wave mode in a one-dimensional acoustic resonant cavity, so that the length of the resonant cavity is greatly shortened, and meanwhile, the size of a sensor is reduced.

The invention relates to an ultraviolet three-frequency high spectrum resolution laser radar system based on three-channel FP etalon and a detection method thereof, wherein the system and the method can be used to simultaneously detect a 0-35km height wind field, a temperature and an aerosol in a high precision mode. The system is characterized in that an emission laser frequency is alternatively changed among v0, v0-2GHz and v0+2GHz; channels L, 1 and 2 of the etalon are designed into one body, a free spectral spacing is 8GHz, spectral widths are 0.2GHz, 1GHz and 1GHz, 1-L and 1-2 peak to peak intervals are 0.1GHz and 4GHz; the v0 is locked at a peak value of the channel 1; and a quarter wave plate and a polarizing beam splitter prism form a cascading light path. The system and the method have advantages that a single radar can simultaneously measure the 0-35km height wind field, the temperature and the aerosol in the high precision mode; and disadvantages that detection precision of a single parameter detection technology is not high, a detection range can not be covered and three parameters mutually influence each other so that an inversion error is large are overcome.

The invention provides a loudspeaker diaphragm tester with a controlled excitation source. The tester comprises a to-be-tested platform, the controlled excitation source, a laser displacement sensor and a control device. To-be-tested diaphragm is fixed on the to-be-tested platform. The laser displacement sensor is fixed on the to-be-tested platform. To-be-tested diaphragm and the laser displacement sensor are coaxially arranged on the to-be-tested platform. The control device inputs a control signal into the controlled excitation source. The controlled excitation source generates an excitation signal according to the control signal. The to-be-tested diaphragm is excited by an excitation signal generated by the controlled excitation source to generate vibration. The laser displacement sensor detects vibration information when the diaphragm vibrates. According to the tester, the to-be-tested diaphragm can be excited by the controlled excitation source to vibrate well; physical parameters of the diaphragm are obtained through various channels such as measuring air pressure and diaphragm displacement; and the tester has relatively high test precision and relatively high stability.

The invention discloses a trace gas measurement device and method with adoption of photo-acoustic spectroscopy. A photo-acoustic cell with a double-resonant-cavity structure is used for measurement, two resonant cavities have different lengths and radiuses but have the same resonance frequency, and the same to-be-measured gas enters the two resonant cavities from buffer gas chambers in two ends of the photo-acoustic cell and flows out from a buffer gas chamber between the two resonant cavities. The concentration of the gas is measured indirectly through differential resonance photo-acoustic signals of the two resonant cavities, the influence of related noise caused by a photo-acoustic effect in solids can be reduced obviously, the detecting signal to noise ratio of the photo-acoustic signals is increased, and the detection limit of the trace gas can be further improved.

The invention discloses a sheet air coupled ultrasonic Lamb wave total-focusing imaging detection method. Different from traditional ultrasonic array signal acquisition, only aiming at a single soundvelocity medium, propagation time of sound waves in air needs to be taken into consideration for acquisition of air coupled array signals. Therefore, the sound velocity ca in the air and the propagation speed cg of the Lamb wave in a plate are measured by using a standing wave method and a wave velocity method respectively. The acquired air coupled ultrasonic Lamb wave array signals exist in the form of a three-dimensional matrix Nti x Ntj x A, the acquired air coupled ultrasonic Lamb wave array signals are subjected to division of an imaging grid region, according to the arrangement positionof a probe, the defect position, and the sound wave propagation speed, the delay time of each scanning path is calculated, and delay superposition total-focusing imaging of the signals is realized according to a delay rule of the sound waves. According to the method, the high-quality ultrasonic total-focusing technology is expected to be expanded to the sheet air coupled ultrasonic Lamb wave imaging detection, so that the defect detection capability is effectively improved.

The invention provides a light splitting slice and a laser coaxial range finder and application thereof. The laser coaxial range finder comprises a light beam source and comprises a second lens, the light splitting slice, and a first lens which are successively arranged along an optical axis direction. The light splitting slice is provided with a half reflection zone and a reflection zone. Light beams emitted from the light beam source pass the half reflection zone and the first lens to form parallel light beams to irradiate a target object. Light beams reflected by the target object are converged by the first lens and are reflected by the reflection zone and the half reflection zone to a measurement position or observation position. A light-slitting system can be used in a measurement system or observation system. The laser coaxial range finder solves a problem that laser reflected by an object leaks so as to cause a detection blind spot in a pitting method. The laser coaxial range finder improves a detection signal-to-noise ratio, and achieves coaxial measurement of common objects and coaxial measurement of far objects, weak-reflection objects, and mirror objects.

The invention discloses a time division multiplexing based single-detector all-fiber polarization lidar. The lidar adopts all-fiber link, utilizes a delay fiber to realize time division multiplexing, and uses a single detector to realize simultaneous detection of parallel polarization signals and vertical polarization signals in radar echoes. Detection of atmospheric depolarization ratio is realized with the single detector, and the liar has the advantages of low cost, system stability, relative eye safety, all-fiber link, compact structure and the like.

The invention provides a fluorescent probe for detecting biological hydrogen sulfide, of which the fluorescence emission wavelength is greater than 500nm. The fluorescent probe has high stability, and thus, can be stored and used for a long time. The fluorescent probe can effectively avoid interference from the biomacromolecule background fluorescence. The fluorescent probe does not have fluorescence itself, has fluorescence only after reaction with H2S, and has high signal to noise ratio for detection and favorable sensitivity. The fluorescent probe has excellent selectivity, and can specifically detect H2S in a complex biological sample. The fluorescent probe has favorable biomembrane permeability, and thus, can be used for specific detection of biological hydrogen sulfide in living cells. The structural formula of the fluorescent probe is disclosed in the specification.

The invention relates to the technical field of radar communication, and discloses a passive radar processing method based on multi-radio-station signals. The passive radar processing method comprises the following specific steps of: step 1, carrying out down-conversion, low-pass filtering and the like on target echo signals received by a main radar channel to extract target echo baseband signalsof each radio station; meanwhile, carrying out down-conversion, low-pass filtering and the like on a plurality of radio station direct wave signals received by a secondary radar channel to extract direct wave baseband signals of each radio station; step 2, filtering the target echo signals of each radio station obtained in the step 1 to inhibit interference signals in the target echo signals, particularly direct wave interference signals; step 3, carrying out relative processing, namely matched filtering, on the target echo signals processed in the step 2 to obtain matched output signals; andstep 4, carrying out phase compensation on the matched output signals and then performing coherent synthesis on the processed signals; and sending the processed signals into a detector for follow-up processing such as target detection and the like.

One laser radar which is used for the measuring the wind field as a pilot balloon is microwave modulating. including the system of the pulse laser and extending-string mirror; the receiving system including the telescope , optical fiber, narrow-cut filter; the frequently system is made up of the light-sensitive detector and the telescope; the data handling system is composed of the analog digital transmitting setting, the computer, the software modulation of amplitude of nanosecond pulse the laser radar, the Doppler shift of the scattering of the air molecule and the gas-solid is achieved by the microwave frequency. Compared with the measuring wind laser radar, the invention keep the good points of the directivity of the laser radar room, the high standard of the distinguishing ability .the intimation of the sending wave-length, is adapt to the different requirements of the aircraft and military. Pulse modulation improves the signal to mask radio greatly. The sending of laser radar and the frequency of technical methods own the advantage of both the laser radar and microwave radar, countering the balance of the disadvantage of the present technology, the invention means a lot to the development of laser radar and the popularization of it in our country.

The invention relates to a magnetic resonance multi-channel detection method and apparatus using a pre-polarization field to enhance the amplitude of a signal. The method comprises: a plurality of direct-current transmitting coils and a direct-current / alternating-current transmitting coil are set, direct currents are emitted to form a pre-polarization field, and the magnetization intensity of hydrogen protons in water is enhanced; after emission for a period of time, the direct currents are cut off, the direct-current / alternating-current transmitting coil emits an alternating current with aLarmor frequency to excite the hydrogen protons to generate a magnetic resonance phenomenon; after the alternating current is cut off, the hydrogen protons release freely-sensing attenuation magneticresonance signals, and a plurality of receiving coils and one reference coil are set to measure magnetic resonance signals and noise signals; and the alternating current amplitude is controlled to complete measurement of different pulse torques. Therefore, the signal amplitude is enhanced; the detection signal-to-noise ratio is increased; and detection on a non-layered complex water-containing structure is carried out to realize multi-dimensional magnetic resonance measurement of a uniform pre-polarization field in a high-noise environment like an environment with manual noises or serious power interference or a large tunneling area like a tunnel or mine.

The invention discloses a double-wavelength single receiving channel-based rotation Raman temperature measurement laser radar. The laser radar is based on two working wavelengths and a single receiving channel. The two working wavelengths of the laser radar are respectively composed of odd number pulses and even number pulses. The low-quantum-number rotation Raman signals of one working wavelength and the high-quantum-number rotation Raman signals of the other working wavelength are extracted by the receiving channel of the laser radar. The laser radar is operated alternately at the two working wavelengths in the time division multiplexing manner. The atmospheric temperature is calculated based on the ratio of high-quantum-number rotation Raman signals to low-quantum-number rotation Raman signals. According to the technical scheme of the invention, the rotation Raman temperature measurement is realized only by means of a single filter, a single detector and a single acquisition card. Compared with a single-wavelength double receiving channel-based rotation Raman temperature measurement laser radar, the above laser radar is compact in structure, wherein the difficulty of optical path adjustment and the difficulty of system parameter calibration are lowered. Meanwhile, the double-wavelength single receiving channel-based rotation Raman temperature measurement laser radar is low in cost. The working performance difference between the filter and the detector caused by the inconsistence of working environments can be avoided. Moreover, the detection accuracy, the system stability and the environmental adaptability are improved.

The invention discloses a ship radar anti-same-frequency-interference signal processing method based on an FPGA. Video echo signals are processed through analog-digital conversion and then subjected to three-pulse staggering time sequence processing, meanwhile, anti-interference variables are superposed, and dynamic synchronous interference asynchronization is achieved; the echo signals processed through synchronous interference asynchronization are subjected to improved three-pulse reverse asynchronous processing; finally, sliding window accumulation is performed on the echo signals subjected to reverse asynchronous processing. Compared with the prior art, the ship radar anti-same-frequency-interference signal processing method based on the FPGA has the advantages that on the basis of a random circuit and mode correction, dynamic staggering of the radar transmission period is achieved through time sequence design; the capacity for detecting small targets and targets in interference units is improved through improved three-pulse reverse asynchronous correlation; through the sliding window accumulation processing, same-frequency interference residues are further reduced, and the signal-to-noise ratio of detection is increased.

The invention provides a type of fluorescent probes for detecting formaldehyde. The probes have the structures shown as formulas I to IV. Benzene ring correspondingly substituted coumarin is firstly subjected to backflow reaction with Lawson reagents in toluol; an obtained product continuously performs backflow reaction with hydrazine hydrate in ethanol. The fluorescent probes per se provided by the invention do not have fluorescence in the water solution, but can take a specific fast reaction with formaldehyde to produce products with strong fluorescence, so that the specific sensitive detection and quantitative analysis of formaldehyde is realized. The stability is high; the long-time storage use can be realized; the detection signal-to-noise ratio is high; the sensitivity is high; the excellent selectivity is realized; the specific formaldehyde detection in complicated biological samples can be realized; good biomembrane permeability is realized, so that the fluorescent probes can be used for formaldehyde detection in living cells; the detection reaction is fast; the detection result can be given within 1 minutes for formaldehyde in the water solution; during the formaldehyde detection, the formaldehyde concentration in the environment cannot be influenced. The general molecular formulas of the probes provided by the invention are shown as the accompanying drawing.

The invention provides a device of detection time-resolved transient absorbance spectrum. The device includes a pumping unit, a detection unit, and an analysis unit. The pumping unit is used for emitting pulse laser to pump and stimulate the sample to be measured. The detection unit is used for emitting wide spectrum detection beam to irradiate the pumped and stimulated area of the sample to be measured. The analysis unit is used for analyzing the changes of the absorption spectrum and absorbancy of the wide spectrum detection beam of the sample to be measured before and after suffering pumping and stimulating. The detection unit comprises a light intensity or phase modulator, and the analysis unit comprises an optical filter and a lock-in amplifier.

The invention relates to a laser three-dimensional compressed imaging technology, in particular to a three-dimensional compressed imaging method and device based on a phase position distance measurement principle, and belongs to the field of laser imaging and digital image processing. The recovery method of the phase position difference of echo of each point of a target surface is studied through a compressed sensing recovery algorithm, and therefore the purpose of three-dimensional imaging is achieved. The three-dimensional compressed imaging device based on the phase position distance measurement principle comprises a cosine signal generator, a semiconductor laser, a collimation and beam expanding module, an imaging optical system, a semi-reflective semi-transmittance lens, a digital micro mirror array, a focusing lens, an avalanche photodiode, a phase measurement module, a central processing module and a DMD driving module. The three-dimensional compressed imaging method and device based on the phase position distance measurement principle can further improve the distance measurement accuracy, and lower the requirement for the speed of an AD converter.

The disclosed device comprises three pieces of parallel placed convex lenses with coincided centerlines, a beam splitting plate, a plane reflector and a Bragg acousto-optic modulator. Received by lens 1 and passing through lens 2, an inquire light becomes a narrow beam. Then, passing through the beam splitting plate, the beam is divided into a transmission light and a reflection light. The transmission light is a receiving signal. Reflected by the plane reflector, the reflection light forms an echo light beam and passing through the Bragg acousto-optic modulator to return in direction parallel to the inquire light. Diaphragm and light filter can be added to the device to filter the inquire light in space and frequency in order to raise detection SNR at response party. Features are: small loss of luminous energy, simple structure, and small size. Moreover, the invention increases communication and identification distances, and possesses better modulation effect.

The invention relates to an unknown target line spectrum detection method based on phase variance weighting and a system thereof. The unknown target line spectrum detection method is characterized in that a signal radiated by an unknown target can be received by a receiving array element; the signal received by the receiving array element can be filtered and amplified, and the sampling of the filtered and amplified data can be carried out to acquire a discrete signal, and by the Fourier conversion analysis of the discrete signal, the spectrum data can be acquired; various frequency unit phases can be extracted from the spectrum data; the signal received by the receiving array element can be updated, and the previous steps can be repeated until the number of the repeated times reaches the preset value M, and then every frequency unit is provided with M phase values; the variance calculation of the phase values of the frequency units can be carried out; the phase variance weighting statistic of all of the frequency units can be carried out to acquire the estimation values of the final spectrum, and the maximum value can be acquired from the estimation values of the final spectrum to acquire the estimation value of the signal line spectrum; and the estimation value of the signal line spectrum can be used to detect the line spectrum of the unknown target of the underwater target radiation noise.

The invention relates to a laser measurement method and a device for the light obscuration of inorganization-emission particulate smoke plume. The device disclosed by the invention is used for measuring the light intensity of a light source and the light intensity of a signal after passing through the smoke plume simultaneously, with less interference of environment and background light; and the light-emitting end and the light-receiving end of the device are integrated; the laser emitted by a laser device in the device disclosed by the invention is reflected via a reflector at first, and then divided into a transmitting light and a reflected light by a beam splitter; the transmitting light is detected by a light source signal detector, the reflected light is beam-expanded via an off-axis parabolic mirror and then penetrates through the to-be-measured particulate smoke plume, and then reflected back to the off-axis parabolic mirror via a corner reflector at the other side of the smoke plume; the reflected light is collected by the off-axis parabolic mirror and then received by another detector; and the signals received by the two detectors are converted by an analogue / digital converter and then output to a computer. The invention aims at providing an open-circuit type measurement device for light obscuration, which is compact in structure and strong in portability; and the device is suitable for rapid and continuous detection for the light obscuration of outdoor inorganization-emission particulate smoke plume.

The invention provides a low light level imaging detector. The detector comprises a casing (7), an input window (1), a photoelectric cathode layer (2), a micro-channel-plate image enhancer (3), an inductive coding anode (4), vacuum electrodes (6) and electrode leads (5), wherein the input window (1) and the metal casing (7) form an enclosed high-vacuum environment, and the photoelectric cathode layer (2), the micro-channel-plate image enhancer (3), the inductive coding anode (4) and the electrode leads (5) are all arranged in the high-vacuum environment. The low light level imaging detector can effectively reduce the aberration of a detection image, reduce the amount of used optical components and improve the imaging quality, and also has the advantages of simple structure, reasonable design, simple preparation process, high preparation efficiency and high quality.

An Si-PIN four-quadrant photoelectric detector based on MEMS microstructure silicon and a manufacturing method thereof belong to the technical field of photoelectric detection. The Si-PIN photoelectric detector of each quadrant of the four-quadrant photoelectric detector comprises a silicon intrinsic substrate 1, a P-type zone 4 positioned above the center of the front surface of the silicon intrinsic substrate, annular P+ zone 3 positions on the periphery above the center of the front surface of the silicon intrinsic substrate, an N-type MEMS microstructure silicon layer zone 2 Located below the silicon intrinsic substrate, upper electrodes 5 positioned on the both sides of the surface of the P type zone and P + zones and a lower electrode 6 positioned on the lower surface of the N-type MEMS microstructure silicon layer zone. Each unit detecting device is separated by an isolating groove, thereby effectively reducing signal crosstalk between small-quadrants. Compared with a traditional Si-PIN four-quadrant photoelectric detector, the Si-PIN four-quadrant photoelectric detector of the invention have characteristics of high responsibility, a broad responding wave band scope and a high between-quadrant signal-to-noise-ratio, etc. The function and the usage scope of the four-quadrant photoelectric detector can be expanded to satisfy demands of large scale marketization application.

An ultraviolet laser bioparticle counter for measuring the diameter and biological characteristics of the bioparticles suspended in air is composed of ultraviolet laser lighting path using ultraviolet laser device as light source, scattered light receiving path, fluorescence receiving path, and sampling air channel. It is characterized by that the filter in scattered light receiving path can reflect all fluorescence and the filter in fluorescence receiving path can reflect all ultraviolet laser beam. Its advantages are multiple function, and high sensitivity, receiving efficiency and S / N ratio.

A magnetic field modulated multi-target X-ray source for spatial X-ray communication comprises a cathode structure, a focusing groove, an electron emission source, a glass shell, a Kovar alloy ring, afocusing electrode, a modulation electromagnetic device, a multi-target metal anode, and a transmission window. The cathode is connected with a negative high voltage, the electron emission source isdisposed in the focusing groove, the glass shell and the focusing electrode are in tight coupling by the Kovar alloy ring, the modulation electromagnetic device is disposed near the multi-target metalanode, the multi-target metal anode is grounded, and one side is facing a focus channel and the other side is plated on the transmission window layer. The magnetic field modulated multi-target X-raysource utilizes a fast-responding high-frequency modulation magnetic field, changes the electron motion trajectory to bombard the multi-target metal anode, excites characteristic X-rays of different energies, and uses characteristic X-rays of different energies as signal transmission carriers to solve the problem that the existing intensity modulation X-ray source technology is less in loading symbol signal and low in communication rate. The magnetic field modulated multi-target X-ray source has the advantages of multiple types of loading symbol signals and large communication rate.

The invention provides a GNSS long code signal capturing method and device assisted by a low earth orbit satellite. The GNSS long code signal capturing method assisted by the low earth orbit satellitecomprises the following steps: acquiring GNSS baseband signals; performing frequency mixing operation; performing segment correlation operation; performing long-time coherent integration; carrying out incoherent integral operation; and performing peak detection and threshold judgment. The method and the device have the advantages that GNSS navigation signal auxiliary information, including roughDoppler information and rough code phase information, is acquired under the assistance of a low-orbit satellite, so that on one hand, the rough code phase information is used for generating sub-codesof local ranging codes and participating in related operation; it is guaranteed that the influence of bit hopping on coherent integration time is eliminated after correlation operation, high-sensitivity capturing of long codes is achieved through long-time coherent integration, and the long code signal capturing performance in the low signal-to-noise ratio environment is improved; and on the otherhand, rough Doppler information and rough code phase information of the GNSS navigation signals are utilized, the searching time of the signals in the frequency dimension and the code dimension is shortened, the capturing efficiency is improved, and rapid capturing of GNSS long code signals is achieved.

The invention provides a flow-through fluorescence detection cell. The flow-through fluorescence detection cell comprises an upper clamping member, a lower clamping member and a quartz tube. The upper clamping member has a cylindrical structure, the lower end surface of the upper clamping member is provided with a through rectangular upper groove, and the upper end surface of the upper clamping member is downward vertically provided with a light through hole; the top of the lower clamping member is provided with a through rectangular lower groove; and the quartz tube is clamped between the upper groove and the lower groove as a flow-through cell, and the through directions of the upper groove and the lower groove parallel to the axial direction of the quartz tube. Light from a light source goes through the through hole and irradiates to the quartz tube, and strongly reflected excitation light generated by an air-quartz tube external surface optical interface is blocked by two inner side edges of the upper groove, and cannot be propagated to a fluorescence collection light path, so the high background noise caused by reflected excitation light is effectively weakened, and the detection signal-to-noise ratio is improved. The detection cell has the advantages of simple structure and easy manufacturing, and is suitable for capillary electrophoresis, liquid chromatography and flow analysis fluorescence detectors.