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 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.

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 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 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.