18 results about "Noise temperature" patented technology

The invention discloses a microwave cold noise source fusing TEC temperature control and noise temperature compensation technologies, and belongs to the technical field of microwave radiometer calibration. The device comprises a cold source module, a noise compensation module and a constant-temperature control module, wherein the cold source module generates a low-temperature noise signal through a field-effect tube and a terminal resistor; the noise compensation module detects environment temperature change in real time based on a thermistor and a Wheatstone bridge, drives a noise diode to generate a compensation signal, couples the compensation signal with a cold source noise signal after attenuation, and counteracts noise temperature deviation caused by the environment temperature. The constant temperature control module adopts a platinum resistance sensor and a PID algorithm to control a Peltier element in a closed-loop mode, and accurate adjustment (+ / -0.1 DEG C) is achieved. According to the invention, noise compensation and TEC negative feedback temperature control technologies are combined, so that the noise temperature of the system is stabilized in a range of + / -0.1 K for a long time, the measurement precision and reliability of the microwave radiometer in an outdoor complex environment are remarkably improved, and the method is suitable for scenes of remote sensing detection, unmanned aerial vehicle monitoring and the like.

The invention relates to the technical field of spectral analysis, in particular to a crop growth state real-time monitoring method, which comprises the following steps of: acquiring hyperspectral data and temperature data consisting of all wavebands and reflection intensities at each sampling moment; acquiring a spectrum curve at each sampling moment and a progressive line of each wave band; calculating an asymptotic line noise evaluation coefficient, and further obtaining an asymptotic line difference coefficient; calculating a spectrum progressive temperature drift coefficient at each sampling moment, forming a temperature drift verification sequence at each sampling moment according to the hyperspectral data and the temperature data, and further obtaining a temperature drift verification factor at each sampling moment; calculating a noise temperature drift verification coefficient, and obtaining a self-adaptive wavelet threshold value of each decomposition layer number at each sampling moment; and denoising the hyperspectral data at each sampling moment according to a self-adaptive wavelet threshold to obtain the growth condition of the crops. The invention aims to solve the problems of incomplete noise reduction and excessive smoothness of signals caused by a fixed threshold in traditional wavelet threshold filtering.

The invention provides a sidelobe cancellation diagonal loading capacity calculation method, which comprises the steps of calculating theoretical noise power through noise temperature of a system, and calculating a first diagonal loading capacity according to the theoretical noise power; calculating the current noise power of the system through the actual echo signal, and determining a second diagonal loading amount according to the current noise power; taking the smaller one of the first diagonal loading capacity and the second diagonal loading capacity as the current diagonal loading capacity; the second diagonal loading amount is updated in real time according to the current noise power of the system, and when the updated second diagonal loading amount is larger than the current diagonal loading amount, the first diagonal loading amount serves as the current diagonal loading amount; and otherwise, taking the updated second diagonal loading amount as the current diagonal loading amount. The diagonal loading amount is dynamically updated through the real-time echo signal state, and the performance of a sidelobe cancellation algorithm can be effectively improved.

An apparatus for correcting a temperature of an object using a shutter may comprise a temperature measurement module for measuring the temperature of the object and a temperature of the shutter, a noise temperature calculation module for calculating the temperature due to noise using the measured temperature of the shutter, and a temperature correction module for correcting the temperature of the object by subtracting the calculated temperature due to noise from the measured temperature of the object.

The invention belongs to the field of radio detection, particularly relates to a phased array incoherent scatter radar background noise calculation method and system, and aims to solve the problem of background noise calculation in phased array incoherent scatter radar detection. The method comprises the following steps: calculating the sky noise temperature of a corresponding detection point according to any detection beam selected in a radar grating lobe-free detection area; a space included angle between the sun position and the detection point position is obtained, and the sun noise temperature of the detection point is determined by combining radar system parameters; determining the atmospheric noise temperature of the detection point according to the elevation angle of any detection wave beam and the detection environment temperature; and comprehensively calculating the sky noise temperature, the sun noise temperature, the atmospheric noise temperature and the system noise temperature of the radar to obtain the background noise temperature of the detection point. According to the invention, the background noise temperature of the phased array incoherent scatter radar can be accurately calculated, and the background noise state detected by the radar can be effectively obtained.

An embodiment of the present invention provides a method, device, and equipment for calibrating the gain of the reflection channel of an occultation detector. The method includes: under preset ambient temperature conditions, inputting two or more calibration sources into the reflection channel of the occultation detector respectively, and outputting the DDM noise observation values corresponding to each calibration source; obtaining the gain deviation values caused by the deviation of the AD sampling values of each calibration source from the target values; determining the equivalent noise temperature corresponding to each calibration source, and determining the equivalent input noise power based on the equivalent noise temperature; determining the total gain of the reflection channel of the occultation detector and the system noise figure based on the DDM noise observation values, the gain deviation values, and the equivalent input noise power. Through the embodiment of the present invention, the calibration of the gain of the reflection channel of the occultation detector is achieved.

A kind of receiver noise figure test method based on high-precision radiation measurement, different brightness temperature signals of calibration source output are used to calibrate receiver in real time, and high-precision measurement of receiver noise figure can be realized by calculating equivalent noise temperature.The whole simulates actual brightness temperature scene, and radiation measurement method is more accurate, which improves test precision;Calibration source realizes accurate and stable cold source and heat source based on liquid nitrogen refrigeration and physical heating, has the advantages of high output precision and long stability time, and long-time stability precision can reach 0.1k / 3 days;At the same time, the output brightness temperature of high-precision calibration source is between 90K and 330K, which is closer to actual brightness temperature scene, and can avoid the large non-linear error of receiver caused by the non-linearity of its internal amplifier, greatly improving the test precision.

The present invention discloses an improved calibration method for the sky tilt curve of a microwave radiometer, which comprises the following steps: Step 1, assuming the noise temperature of the reference source, designing a non-linear system model of the microwave radiometer; Step 2, measuring and calculating the brightness temperature at different zenith angles; Step 3, obtaining the total atmospheric attenuation at each zenith angle by using the brightness temperature at each zenith angle and the average atmospheric radiation temperature; Step 4, performing linear regression on the total atmospheric attenuation and the secant value of the zenith angle, and carrying out the calibration process and other steps. The calibration method and device disclosed by the present invention solve the problems that the ground-based microwave radiometer is affected by the average atmospheric temperature and system non-linearity during the calibration of the sky tilt curve. It can improve the calibration success rate of the ground-based microwave radiometer during long-term unattended operation, thereby ensuring the detection accuracy during long-term operation.

The present application relates to the technical field of testing, in particular to a noise figure test automatic calibration, compensation and correction method and system. The method comprises the following steps: obtaining the loss L of a microwave switch matrix; obtaining the equivalent noise temperature obtained by a test of a measured object and the test gain of the measured object; obtaining the real equivalent noise temperature of the measured object based on the loss L of the microwave switch matrix, the equivalent noise temperature obtained by the test of the measured object, the test gain of the measured object, a standard noise temperature; and converting the real equivalent noise temperature of the measured object into the real noise figure of the measured object. The present application can realize automatic calibration and compensation of noise figure test based on the Y-factor method, and support full-automatic testing of an automatic test system.

The application belongs to the field of radio detection, and particularly relates to a phased array incoherent scatter radar background noise calculation method and system, aiming to solve the problem of calculating background noise in phased array incoherent scatter radar detection. The application comprises: calculating the sky noise temperature of a corresponding detection point according to any detection beam selected by the radar grating-free detection area; obtaining the spatial angle between the position of the sun and the position of the detection point, and combining the radar system parameters to determine the sun noise temperature of the detection point; determining the atmospheric noise temperature of the detection point according to the elevation angle of any detection beam and the detection environment temperature; and comprehensively calculating the sky noise temperature, the sun noise temperature, the atmospheric noise temperature and the system noise temperature of the radar itself to obtain the background noise temperature of the detection point. The application can accurately calculate the background noise temperature of the phased array incoherent scatter radar, and effectively obtain the background noise state of the radar detection.

The application discloses a kind of methods for measuring antenna noise temperature, belong to antenna measurement technical field.The application includes: in antenna field installation antenna to be measured, utilize antenna servo controller to drive antenna points to clear sky, there is no shelter in front of antenna;The state parameter of spectrum analyzer is set, and the noise power density of system output is measured using the noise measurement function of spectrum analyzer;Directly calculate antenna noise temperature from the noise power density of system output measured.The measurement method of the application is simple and easy to operate, and has high popularization and application value.

An aspect of the disclosure provides an apparatus comprising: an electromagnetic resonator configured to support an oscillating electromagnetic field in a sample; a cold load having a noise temperature lower than the noise temperature of the electromagnetic resonator; a coupler controllable to provide: a first coupling between the electromagnetic resonator and the cold load to reduce the noise temperature of the electromagnetic resonator; a second coupling, different from the first coupling, to the electromagnetic resonator for sensing an electromagnetic field associated with the sample.

The application discloses a kind of low-noise amplifier equivalent noise temperature measurement system and method, measurement system includes: load component, for providing thermal noise signal, including first load and second load, the first load and the second load are located in temperature different first temperature zone and second temperature zone respectively;The input end of the low-noise amplifier to be measured is electrically connected with the first load or the second load and receives thermal noise signal;Second amplification component is connected with the output end of the low-noise amplifier, amplifies the output signal of the low-noise amplifier, and the second amplification component meets impedance matching with the low-noise amplifier;Measuring device is used to measure the signal output by second amplification component, and obtain the equivalent noise temperature of the low-noise amplifier.The end of the low-noise amplifier connected with load is switched in different temperature zones, and the uncertainty factor in measurement is reduced.

Provided is a radar echo level calibration system capable of accurately determining the magnitude of a received echo by calibrating the entire receiver chain using a measured value of the noise level of the receiver chain. A radar echo level calibration system (100) comprises: an antenna having an observation period during which transmission and reception of radio waves are performed, and a non-observation period during which the transmission and reception of radio waves are not performed; a measurement means for measuring a reception gain and a noise temperature by measuring the noise level during the non-observation period while alternately generating two noise temperatures having a temperature difference periodically or aperiodically; a noise temperature calculation means for obtaining an antenna noise temperature by observing noise received in the period during which transmission of radio waves from the antenna is stopped; and a power calculation means for calculating the power of an echo of interest from the ratio between the power value of the noise level and the power value of the echo of interest by performing digital-level calibration using the noise level.

The present application discloses a method for determining the operating noise temperature of a parametric amplifier, wherein the parametric amplifier is the first element in a quantum amplification chain. The method comprises: respectively presetting first and second relationships between first and second powers of the output signal of the quantum amplification chain corresponding to when the driving signal of the parametric amplifier is in operation and not in operation, and fixed parameters of the first and second elements in the quantum amplification chain; determining a third relationship representing the noise temperature of the parametric amplifier based on the first and second relationships; measuring and obtaining first and second power values of the output signal of the quantum amplification chain when the driving signal of the parametric amplifier is in operation and not in operation; and determining the operating noise temperature of the parametric amplifier based on the first and second power values and the third relationship. The present application proposes a method for measuring the operating noise temperature of a parametric amplifier.

To provide a radar echo level calibration system capable of accurately determining the magnitude of a received echo by calibrating the entire receiver system using a measured value of a noise level of the receiver system.SOLUTION: A radar echo level calibration system 100 comprises: an antenna having an observation period during which transmission and reception of radio waves are performed, and a non-observation period during which the transmission and reception of radio waves are not performed; measurement means for measuring a reception gain and a noise figure by measuring the noise level during the non-observation period while alternately generating two noise temperatures having a temperature difference periodically or irregularly; noise temperature calculation means for obtaining an antenna noise temperature by observing noise received in the period during which transmission of radio waves from the antenna is stopped; and power calculation means for calculating the power of an echo of interest from a ratio between a power value of the noise level and a power value of the echo of interest by performing digital-level calibration using the noise level.SELECTED DRAWING: Figure 1

A waveguide receiver apparatus includes a power splitter circuit with an attenuation card; a mixer circuit coupled to an output of the power splitter circuit; and an antenna assembly coupled to an output of the mixer circuit. The aspects of the disclosed embodiments provide a highly compact and sensitive 500-600 GHz, 1×8 receiver array, with a conversion loss of less than approximately 11 decibels (dB), a noise temperature of less than 2000 degrees Kelvin (K) at 540 GHz, and a wide intermediate frequency (IF) bandwidth of approximately 70 Gigahertz (GHz).