38 results about "Square law detector" patented technology

The invention provides a foundation-based atmosphere profile microwave detector. The detector is characterized by comprising an antenna feeder unit, a radiometer receiving unit and a scanning mechanism unit, wherein the antenna feeder unit comprises two independent antenna feeder sub-units for two wavebands and is provided with two-frequency independent reflective surfaces; the two independent antenna reflective surfaces are arranged at two ends of the output shaft of a scanning motor respectively, can realize beam scanning through motor rotation, and are used for receiving microwave radiation of atmosphere and an internal calibration reference source; the radiometer receiving unit comprises a directional coupler, a radio amplifier, a power divider, a band pass filter, a square law detector, an integrator and a video amplifier, and is used for realizing intermediate frequency detection of a received signal; the scanning mechanism unit comprises a scanning shaft, a scanning step motor, two front ends and a sub-miniature type A (SMA) connector; and driven by the scanning motor, the scanning shaft drives the two reflective surfaces to circumferentially scan so as to realize observation on sky in different incident angles and measurement on an internal calibration blackbody and acquire data which is acquired in a measurement and periodic internal calibration unit.

The invention relates to a self-adaptive constant false alarm rate target detection method. The method includes the following steps: 1), transmitting data received by radar into a matching filter; 2), transmitting signals output by the matching filter into a square-law detector for processing; 3), transmitting signals output by the square-law detector into a CFAR (constant false alarm rate) detector for processing, and acquiring an estimation value Z of cluster power level generated by a reference unit according to a corresponding CFAR algorithm through sampling; 4), outputting a final judgment by the CFAR detector according to the estimation value Z acquired in step 3), namely detecting whether a target exists in the unit or not. In the method, according to statistical average value and variance of sampling values in a reference sliding window, the sampling value with the variance larger than a certain numerical value is deleted, an average value of remaining valid sampling values is used to replace the sampling value, and an average value of the sampling values is recalculated.

The invention discloses a high-resolution radar dual-threshold detector based on energy accumulation, belonging to the field of signal processing. Values of all distance units in a distance window, passing through a square-law detector, are compared with a first threshold, quantity and positions a target scattering center are extracted, then energy of the scattering centers is accumulated and compared with a second threshold to obtain a final detection judgment. Compared with the traditional detection, the detector deduces a calculation formula of the threshold to ensure that actual application is more convenience and flexible, is simple in form, is easy to engineering realization, and has better robustness and detection property under the condition of unknown distribution of the scattering centers.

The invention discloses a high-spectrum-resolution total atmospheric spectral transmittance measuring method. The method includes: using a target tracking device for acquiring sunlight or starlight penetrating the atmosphere as signal light, taking a high-coherence narrow linewidth laser as local oscillation laser, subjecting the signal light penetrating the atmosphere and the local oscillation laser to optical mixing in a heterodyne detector prior to passing through an intermediate-frequency filter and a square-law detector, sending to a band-pass filter to remove noise, enabling a computer to collect for obtaining a heterodyne signal generated by combination of the signal light penetrating the atmosphere and the local oscillation laser, and processing the heterodyne signal to obtain a high-resolution spectrum of weak signal light penetrating the atmosphere. The high-spectrum-resolution total atmospheric spectral transmittance measuring method is used for real-time measurement of total atmospheric spectral transmittance and applicable to fields of atmospheric optics, meteorological research, atmospheric pollution monitoring, detection and the like, and quick response and real-time measurement of high-spectrum-resolution total atmospheric spectral transmittance can be realized according to the method.

The invention provides an error rate performance optimizing method of a noncoherent energy detecting UWB receiver, comprising the following steps: the outside band noise of a received signal is filtered via a bandpass filter; the signal is processed by a square-law detector, and after the synchronism process, the SNR estimation is carried out; an energy window is optimized; and an optimized threshold is selected based on a least square fitting correction gauss approximate threshold. The error rate performance optimizing method of a noncoherent energy detecting UWB receiver enables the receiver performance to be greatly improved by the combined optimization of the judgment threshold of the receiver and an energy integral window.

The invention discloses a system for recognizing motor vehicles in an intelligent transportation system. The recognizing system comprises a detector, a receiving antenna and a PC. The detector is a passive millimeter wave detector and is composed of a low noise amplifier, a square-law detector, a video amplifier, a signal processing unit and a power supply unit. The receiving antenna is a millimeter wave antenna. The recognizing method includes the steps that first, the millimeter wave detector works, and a vehicle moves towards a detection area of the detector; second, the millimeter wave detector observes the detection area and outputs signals; third, the PC compares the voltages of output signals of the detector with preset threshold voltages for detecting whether the vehicle can pass or not, and a judgment is made; fourth, under the condition that the judgment that the vehicle can pass is made, the PC compares the voltages of the output signals of the detector with preset threshold voltage ranges of different vehicle models, and according to the fact that the voltages of the output signals of the detector fall into the threshold voltage range of a certain vehicle model, the PC makes a corresponding vehicle type recognizing judgment for allowing the vehicle to pass.

An extended field heterodyne detection apparatus comprises a local signal oscillator, a micro-lens array set in optical relation to the local signal oscillator to multiplex a beam from the local signal oscillator, a local oscillator injection lens in the optical path of the local oscillator and the micro-lens array, a semi-reflective beam splitter at the telecentric stop of the local oscillator injection lens to reflect the beam of the local oscillator in parallel to a signal beam passing through the semi-reflective beam splitter, an objective lens, with a stop, located at the semi-reflective beam splitter, and a focal plane array, situated to receive the source beam. The extended field heterodyne detection apparatus solves the problem of creating a local oscillator beam that is mode-matched for an incoming signal beam, for the eventual process of mixing both the signal beam and the local oscillator using a conventional, square-law detector.

The invention discloses a real-time monitoring microwave dicke radiometer based on a reference load temperature and belongs to the field of microwave passive remote sensing. The radiometer comprises a dicke input switch, wherein a first end of the dicke input switch is sequentially connected with a radio frequency and intermediate frequency amplifying circuit, a square law detector, a low frequency amplifier, a synchronous detector, a low pass filter and a data collecting and processing module, a second end of the dicke input switch is switched between a reference load and an antenna under the driving of a switch signal generator, and a temperature measuring circuit is arranged on the reference load and connected with the data collecting and processing module. The reference load of the microwave dicke radiometer is not required to be kept in a constant temperature state, only the temperature measuring circuit is used for monitoring the temperature changes of the reference load in real time, the monitored variable quantity of the temperature of the reference load is plugged into a radiometer scaling equation for modification, and an antenna temperature of the measured scene is obtained. According to the real-time monitoring microwave dicke radiometer based on the reference load temperature, the measuring accuracy is improved and the structure of the existing microwave dicke radiometers is simplified.

We have designed, built and operated an innovative JTOC system utilizing a holographic photopolymer as the square law detector to record the holographic data for one-step correlation signal requisition in real time. The resultant high-resolution, high-speed JTOC is useful to perform real-time pattern recognition. An example application that has been demonstrated is fingerprint verification.

The invention discloses a passive receiving link for active and passive joint detection of adjacent frequency bands. The passive receiving link comprises a radiometer feed source, a cavity filter, a single-pole double-throw switch, a load, a radio frequency amplification link, a square-law detector and an integral amplification link, wherein the radiometer feed source is used for receiving a target radiation noise signal; the cavity filter is used for suppressing the radar emission signals of the adjacent frequency bands; the radio frequency amplification link is used for amplifying the noisesignal so as to meet the input requirement of the square-law detector; and the integral amplification link is used for outputting detection and performing amplified integral output. The passive receiving link can be applied to the active and passive integrated microwave detecting instrument system of terrestrial water resource satellites, and can also be widely applied to various adjacent satellite-borne active and passive joint detection systems.

The invention discloses a coherent detector for atmosphere greenhouse gas. The coherent detector comprises a light cylinder, a solar tracking device, a collimation optical telescope, a chopper, a local oscillation laser, an optical fiber combiner, a high-speed photoelectric detector, a square law detector, a radio frequency amplifier, a video frequency amplifier, a locking amplifier and a microprocessor. According to the coherent detector for the atmosphere greenhouse gas, by referring concepts of a wireless heterodyne receiver and coherent detection, only when sunlight radiation components ofwhich wavelength is equal to that of laser output by the local oscillation laser are subjected to coherent detection, signals required by people can be output, and the spectral resolution of a sun photometer is increased. The coherent detector for the atmosphere greenhouse gas has the advantages that the contradiction between the sunlight detectivity and spectral resolution of an original photometer is solved, and the coherent detector is suitable for measurement of column concentration of atmosphere greenhouse gas components such as water vapor, carbon dioxide and methane.

The present invention relates to a frequency-shift-keying demodulator (1,1') comprising a phase shifter 2 for shifting the phase of an input signal i(t) by a predetermined degree and for outputting a shifted signal Id(t), a combining unit (3, 4; 31, 32, 33, 41, 42) for combining the input signal i(t) and the shifted signal Id(t) output by the phase shifter 2 and for outputting a corresponding signal r(t) and a low-pass filter 5 for filtering the signal r(t) output by the combining unit (3, 4; 31, 32, 33, 41, 42), and for outputting a low-pass filtered signal r LP (t) the bandwidth of said low-pass filter 5 being matched with the bandwidth of a data signal contained in said input signal i(t). According to the present invention said combining unit (3, 4; 31, 32, 33, 41, 42) comprises at least one adder (3; 31, 32) for adding the input signal i(t) and the shifted signal Id(t) output by the phase shifter 2 and for outputting an added signal and at least one square law detector (4; 41, 42) for receiving the added signal output by the adder (3; 31, 32) and for outputting a squared signal r(t) which is the square of the added signal wherein the combining unit (3, 4;31, 32, 33, 41, 42) outputs the squared signal r(t) to the low-pass filter 5. Furthermore, the present invention relates to a method of frequency-shift-keying demodulating an input signal i(t).

The invention discloses an improved Dick radiometer for detecting a stealth plane. The improved Dick radiometer includes an antenna, a first low noise amplifier, a second low noise amplifier, a thirdlow noise amplifier, a comparative load, a matched filter, a Dick switch , a square law detector, a synchronous detector, a square wave generator, a switch actuator and an output circuit. To overcomethe defect that a bandwidth filter in the conventional radiometers loses an antenna signal, the bandwidth filter is removed; and in order to prevent the signal from being overwhelmed by noise due to the interference of the Dick switch, the matched filter is added in a reference channel, the structure of the Dick radiometer is optimized and improved so as to improve the sensitivity.

In one embodiment, a heterodyne detection system for detecting light includes a first input aperture adapted for receiving first light from a scene input, a second input aperture adapted for receiving second light from a local oscillator input, a broadband local oscillator adapted for providing the second light to the second input aperture, a dispersive element adapted for dispersing the first light and the second light, and a final condensing lens coupled to an infrared detector. The final condensing lens is adapted for concentrating incident light from a primary condensing lens onto the infrared detector, and the infrared detector is a square-law detector capable of sensing the frequency difference between the first light and the second light. More systems and methods for detecting light are described according to other embodiments.

The invention discloses an RF system group delay parameter measuring device which comprises a pulse signal generator (1), a modulator (2), a first RF source (3), a square law detector (5), a second RF source (6), a power divider (7), a first analog-digital converter (8), a second analog-digital converter (9) and a postprocessing module (10); a single-pole double-throw switch (4) comprises a first fixed terminal (401), a second fixed terminal (402) and a moving contact (403). The measuring device utilizes the square law detector to demodulate a modulated signal, so as to avoid introducing errors, and improve the measurement accuracy which is better than 1 ns. The measuring device utilizes the pulse signal generator to generate a code pattern and code rate controllable pulse signal, so as to enable the apertures and time for measurement of the group delay parameters to be adjustable. The measuring device utilizes the single-pole double-throw switch to realize the switching of a signal channel at the output terminal of the modulator, so that the measuring process is simplified. The applicable frequency range of the measuring device is 100 MHz-50 GHz.

The invention discloses an unmanned aerial vehicle-mounted Ka-band microwave radiometer system. The system comprises a Ka wave band antenna, a radio frequency switch, a matching load, a first low noise amplifier, a second low noise amplifier, a band-pass filter, a local oscillator, a frequency mixing circuit, an intermediate frequency amplifier, a variable gain amplifier, a square law detector, a video amplifier, an AD sampling unit, a micro control unit MCU, a temperature measuring unit, an SD storage module, a DA control circuit, a GPS module, a data unvarnished transmission module DTU and a wireless transmission module. Compared with a traditional constant-temperature design, the unmanned aerial vehicle-mounted Ka-band microwave radiometer system adopts a digital gain automatic compensation algorithm and a multi-point temperature correction algorithm, so that a temperature control module and a feedback circuit can be omitted, the power consumption is reduced, and the size and the mass are reduced.

The invention relates to a passive millimeter wave three-dimensional imaging system and an imaging method thereof. The system comprises a main dielectric lens, a sub dielectric lens array, a radiometer receiver array, a digital acquisition circuit and a computer; electromagnetic waves radiated by an object in a field are converged to a sub-lens array plane through the main dielectric lens and then are focused to a radiometer receiver array plane through different sub-lenses, a receiving antenna on a radiometer receiver array receives the electromagnetic waves, signals are sequentially output to a millimeter wave band low noise amplifier, a high-sensitivity square law detector, a low-pass filter, and alow-frequency amplifier; and the output end of the low-frequency amplifier is connected with the input end of the digital acquisition circuit, and the digital acquisition circuit transmits sampling signals to the computer for data processing.