115 results about "Absolute calibration" patented technology

A new measurement system, with two receiver channels per measurement port, has been developed that provides absolute magnitude and absolute phase relationship measurements over wide bandwidths. Gain ranging is used at RF to provide optimum noise performance and a swept YIG preselector filter is used to avoid spurious signals. A new absolute vector error correction method is used to calibrate the measurement system in order to allow for absolute vector measurements, and it also removes the time-varying responses caused by the swept YIG preselector filters. A quasi-reciprocal mixer with a characterized non-reciprocal ratio is used to provide the absolute calibration standard. The two receiver channels can be adapted to a wide variety of applications, including wide bandwidth vector signal analyzer measurements, mixer measurements, and harmonic measurements. The two-channels can also be used as an absolute calibrated transmitter / reflectometer.

Disclosed is an antenna calibration technique for performing absolute antenna calibration. An antenna to be calibrated is positioned in a first position, called a home position, and records data samples from received satellite signals. The antenna is then moved to another location, called a non-home position, and records data samples from received satellite signals while at the non-home position. The antenna is then returned to the home position and records additional data samples. During the time that the antenna to be calibrated is recording its data samples, an auxiliary antenna is also recording satellite signal data samples. The data samples taken by the antenna to be calibrated during the home and non-home positions are differenced with the data samples taken by the auxiliary antenna during the same time period. The differenced data are interpolated to determine, at a particular time, an estimate of what the differenced data would be if the antenna to be calibrated occupied both the home and non-home positions at the same point in time. This allows for determination of the phase center of the antenna to be calibrated by differencing the interpolated estimates.

The invention discloses a method for on-orbit absolute radiation calibration, which comprises the steps of: conducting root calculation on optical thickness of an aerosol; determining parameters of an MODTRAN model according to atmospheric spectral transmittance of a measured wave band; adopting the MODTRAN model with determined parameters, and calculating to obtain atmospheric spectral transmittance on a ground target-satellite path; calculating total solar irradiance on the surface of a target; and calculating entrance pupil radiance of a satellite; looking up DN values of gray scale targets on a satellite digital image, and determining absolute calibration parameters of load carried by the satellite by combining the DN values with the entrance pupil radiance corresponding to the ground target. The invention further discloses a device for on-orbit absolute radiation calibration. By adopting the method and the device for on-orbit absolute radiation calibration, the atmospheric parameter processing procedure for on-orbit absolute radiation calibration of a remote sensing satellite is simplified, and an atmospheric transmission model most accordant with the actually-measured atmospheric condition can be determined, thereby improving the on-orbit absolute radiation calibration precision of the remote sensing satellite.

The present invention relates to an ultrasonic hydrophone sensitivity multi-frequency point absolute calibration method. According to the method, a single-frequency sine filler pulses are utilized to excite a focusing transducer, so that harmonic signals for calibrating the sensitivity of an ultrasonic hydrophone can be generated; the sound pressure magnitude values of harmonic waves at each order are obtained through using an optical method; and a hydrophone to be calibrated is arranged at the same position of a sound field, and the open-circuit output voltage of the hydrophone to be calibrated is measured, and therefore, the sensitivity of the ultrasonic hydrophone at a plurality of frequency points can be obtained through one-time calibration. Since the focusing transducer is adopted to generate a harmonic sound field which is adopted as the calibration signals, frequent replacement of auxiliary transmitters during a broadband calibration process can be avoided, so that calibration efficiency can be improved; a characteristic that the sound waves of the focusing transducer will form quasi plane waves near the sound focus of the sound waves is utilized, so that a condition that the calibration of the hydrophone is required to be carried out in an acoustic far field is avoided, and therefore, the influence of signal distance attenuation can be reduced, and a signal to noise ratio can be improved; and 3) the optical method is adopted to calibrate the sensitivity of the hydrophone, and therefore, the method is an absolute calibration method.

A first self-calibration curve relates a first array image to a first acquired image, the first array image being recorded from application of a first radiation treatment plan to a detector array, and the first acquired image being recorded from application of the first radiation treatment plan to a radiation detector. At least one subsequent self-calibration curve relates at least one subsequent array image to at least one subsequent acquired image, the subsequent array image being recorded from application of at least one subsequent radiation treatment plan to the detector array, and the subsequent acquired image being recorded from application of the subsequent radiation treatment plan to the radiation detector. In some embodiments, the detector array is pre-calibrated to a predefined standard.

The invention discloses a fusion reactor plasma density and temperature diagnosing method based on the Thomson scattering weak coherent technique. The method comprises the steps that a broadband low-coherency intense light source is set, a bandwidth modulator is set, a beam splitting system is set, a reference arm is used for generating an optical path difference and a frequency shift signal, the light returned from the reference arm and a detection arm interferes and passes through an optical grating to be divided into interference spectrum signals with different wavelengths to be received by an array CCD, the incident light direction, namely the axial scattering intensity distribution is obtained through the Fourier transform, and the plasma electron density axial distribution information is obtained through rayleigh scattering or raman scattering absolute calibration; the thermal motion rate information of electrons is obtained through the Doppler broadening of a spectral line, and then the plasma electron temperature distribution is obtained; the horizontal movement adjustment is carried out on the length of the reference arm to change the optical path difference changing so as to achieve measurement on the great depth plasma with the depth larger than 1 m. The electron temperature and density of the fusion reactor plasma are measured online through the Thomson back scattering optical coherent chromatographic technique.

In the case of a method for absolute calibration of an interferometer with the aid of a spherical output wave, comprising an optical element which retroflects the incident spherical wave itself or via a mirror, at least four measuring procedures are undertaken to determine a wave aberration W. The optical element is measured in the at least four measuring positions intrafocally and extrafocally in at least two different rotational angle positions. It is also possible, in addition, to undertake a measurement via a mirror in the cat's eye position (focus 3).

An absolute linear encoder includes a plurality of absolute scales aligned in the detection direction with absolute calibrations, a plurality of detectors for detecting the calibrations on the absolute scales, absolute position data generating portions of each scale for generating absolute position data of each detector, and a calculator for outputting an absolute position over the whole length of connected whole absolute scales adding the absolute position data of each detector and the distance between the detectors. The detectors are fixed at such intervals as to simultaneously detect the calibrations of the two absolute scales adjoining in a scale connecting section. Thus, the long absolute linear encoder which is easy to use is realized at low costs.

A first self-calibration curve relates a first array image to a first acquired image, the first array image being recorded from application of a first radiation treatment plan to a detector array, and the first acquired image being recorded from application of the first radiation treatment plan to a radiation detector. At least one subsequent self-calibration curve relates at least one subsequent array image to at least one subsequent acquired image, the subsequent array image being recorded from application of at least one subsequent radiation treatment plan to the detector array, and the subsequent acquired image being recorded from application of the subsequent radiation treatment plan to the radiation detector. In some embodiments, the detector array is pre-calibrated to a predefined standard.

An integrating sphere transmission radiometer for ontrack spectrum radiation absolute calibration for a remote sensor belongs to the field of ontrack spectrum radiation calibration for a remote sensor. The radiometer comprises an integrating sphere main body, an optical filter detector module and a photoelectric measuring module. The integrating sphere main body is equipped with two openings inside. Reflected light enters, through the two openings, the optical filter detector module and the photoelectric measuring module that are fixed outside the integrating sphere main body. Diffuse reflection paint coats the inside of the integrating sphere main body. The integrating sphere transmission radiometer has the capability of measuring low-power signals in a highly precise manner, exhibits the stable performance for a long period of time, and can serve as a standard space ontrack traceablility low temperature radiometer. The integrating sphere transmission radiometer has the characteristics of converting a power reference into a radiance reference and exhibiting high resolution and low uncertainty reference transmission, so the problem of high-precision ontrack traceablility to SI spectrum radiance absolute calibration for an imaging spectrometer, a satellite remote sensor load and the like is well solved.

The invention provides a ground verification instrument of a satellite-based marine radar height gauge, which is used for performing absolute calibration, performance examination and function test on the satellite-based marine radar height gauge in a laboratory. The ground verification instrument of the satellite-based marine radar height gauge comprises a time service unit, a transceiving control unit, a transmitting unit, a receiving unit, a frequency heald unit and a numerical control unit. The frequency heald unit utilizes an ultra-stable crystal oscillator signal provided by a radar height gauge to be verified as a clock. The time service unit takes charge of providing accurate synchronous time service for the numerical control unit and the radar height gauge. The transceiving control unit takes charge of respectively and simultaneously sending signals transmitted by the transmitting unit to the receiving unit and the radar height gauge and also controlling the receiving unit to receive the signals transmitted by the radar height gauge or the signals transmitted by the transmitting unit. The numerical control unit takes charge of eliminating channel influences of a verification instrument system, generating calibration signals, simulating echo signals of various target scenes and controlling the transceiving control unit, the receiving unit, the transmitting unit and the frequency heald unit.

Aimed at the current situation of poor on-orbit absolute radiometric calibration precision, the invention provides an on-orbit absolute radiometric calibration method based on a benchmark satellite. Sunlight with appropriate intensity is reflected onto a to-be-calibrated remote sensor by a diffuse reflection plate on a benchmark satellite, the influence of atmospheric conditions on a radiation transfer path is got rid of, an accurate apparent radiance is obtained, and thereby an accurate absolute calibration coefficient is obtained. In the invention, the sun, the benchmark satellite and the to-be-calibrated remote sensor are integrated into a geocentric coordinate system, so that the distance between each two of the three and the incidence angle and emergence angle of sunlight on the surface of the diffuse reflection plate on the benchmark satellite can be conveniently obtained, a radiation transfer link model from the sun to the benchmark satellite and to the to-be-calibrated remote sensor is created, and finally, calibration is complete.

By measuring, for an ultra-low-expansion glass material, the frequency dependence of acoustic velocities and attenuation coefficients of bulk waves (longitudinal waves and shear waves), and the density, its fundamental acoustic properties are revealed, and a standard specimen for use in system calibration is prepared. By an absolute calibration method using the standard specimen, absolute values for both the LSAW and LSSCW velocities are obtained. Moreover, there are obtained relationships for the acoustic properties and the coefficient of thermal expansion to evaluate the coefficient of thermal expansion from the acoustic properties. In case there is a distribution of characteristics due to periodic striae, an accurate acoustic property distribution in the substrate can be ascertained and an evaluation performed, by selecting for the substrate a cutting angle with respect to the striae plane.

The invention relates to an absolute calibration device and method for a radio telescope antenna surface type. The absolute calibration device for the radio telescope antenna surface type is composed of a PSD position sensor array, a supporting shaft, annular laser devices and a control circuit. The PSD position sensor array is composed of multiple coaxial PSD position sensor coils, each PSD position sensor coil is composed of multiple PSD position sensor units with multiple position points on a central axis as circle centers, and the photosensitive surfaces are dead against the central axis and are in parallel with the central axis. The supporting shaft is arranged on the central axis and provided with the annular laser devices, and the emitting surfaces of the annular laser devices are perpendicular to the central axis. The device is simple in structure, low in cost and easy to manufacture and assemble. The active reflecting surfaces of the radio telescope are convenient to upgrade, performance of the radio telescope is guaranteed in real time, and the implementation technology is simple.

The invention provides a CCD device quantum efficiency measuring device and method. The device comprises a CCD device absolute quantum efficiency measuring apparatus and a CCD device relative quantum efficiency measuring apparatus, the CCD device absolute quantum efficiency measuring apparatus is used for measuring the absolute quantum efficiency of a CCD device on a 632.8 nm wavelength point, and the CCD device relative quantum efficiency measuring apparatus is used for measuring the relative quantum efficiency of the CCD device within the wavelength range from 300 nm to 1100 nm. According to the CCD device quantum efficiency measuring device and method, a 632.8 nm laser is used for emitting light into an integrating sphere to carry out absolute calibration after the light passes through a power stabilizing system, lasers with different levels of output power can be selected according to different CCD devices, the problem that optical power is low is avoided, no light loss is caused, a standard detector directly traces the source to a low-temperature radiometer on the 632.8 nm wavelength point, and therefore the number of intermediate links is reduced, and uncertainty of measurement is improved.

There is provided a surface plasmon resonance imaging sensor capable of performing absolute calibration comprising: a transparent substrate; a first prism and a second prism formed at one surface of the substrate and symmetrically positioned with reference to the center axis of the substrate; an optical system for providing light to the first and second prisms; and a light receiving part for detecting the light reflected from the substrate, wherein a surface plasmon resonance (SPR) angle change of an object to be measured by the first prism is measured, and a refractive index change on each pixel of the object is obtained as a two-dimensional difference image by the second prism.

The invention relates to an absolute calibration method for the radiation intensity of a Hadamard transform imaging spectrometer. In the method, an integrating sphere light source, a uniform attenuation sheet, an electric translation platform capable of translating along a direction vertical to an optical axis, a Hadamard transform spectrometer, a spectrometer radiation intensity meter, a main control computer and a camera obscura are arranged, wherein the Hadamard transform spectrometer and the spectrum radiation intensity meter are fixedly arranged on the electric translation platform respectively, and are arranged at the two ends of the electric translation table along the translation direction; the electric main control computer can be used for controlling the translation of the electric translation table; the electric main control computer is connected with the Hadamard transform spectrometer and the spectrum radiation intensity meter respectively to acquire output data of the Hadamard transform spectrometer and the spectrum radiation intensity meter; and light emitted from the integrating sphere light source can vertically enter the Hadamard transform spectrometer or the spectrum radiation intensity meter after passing through the attenuation sheet. Due to the adoption of the method, the technical problem of the lack of a calibration method for the radiation intensity ofa front slot type Hadamard transform spectrum spectrometer is solved. The calibration method is simple, and has high efficiency.

The invention relates to a method for adjusting remote sensing satellite absolute calibration attitude relative to moon and belongs to the technical field of imaging relative to moon. Through rotation of a satellite around a satellite attitude Z axle, crosswise image motion of the remote sensing satellite absolute calibration relative to moon is prevented. Based on high-precision sampling data, through algorithm modeling recursion, a satellite attitude control angular speed is obtained and through integration of the satellite attitude control angular speed, a control rule of a satellite yawing axis attitude angle is obtained. The method realizes satellite attitude maneuvering imaging. In attitude adjustment method design, through adjustment of a method for acquiring an observation speed-height ratio based on moon as a view field center through control of rotation of a satellite around a satellite Y axle, accurate attitude angle data in a period is acquired and used so that longitudinal image motion of absolute calibration relative to moon is prevented. In an absolute calibration period, through control of a simulation time step n of a simulation tool set, multiple sampling point numbers are acquired and are used as input of a mathematic model so that modeling and simulation precision is improved.

The invention discloses a spectrum calibration system suitable for a thermal infrared hyperspectral imager. According to the calibration system, a globar can emit stable thermal infrared radiation, and the thermal infrared radiation enters a monochrometer through a focusing lens, a reflector and a beam expanding lens, the thermal infrared radiation with the high spectral resolution is emitted after beam split is conducted on the thermal infrared radiation through the monochrometer and is received by the thermal infrared hyperspectral imager, spectrum calibration is conducted through a wavelength scanning method, and spectral response functions of all wave bands are obtained. After wavelength scanning spectrum calibration is conducted on the thermal infrared hyperspectral imager through the globar, a monochrome beam emitted by a wavelength-tunable CO2 infrared laser serves as a light source, a plurality of characteristic wavelengths of the wavelength-tunable CO2 infrared laser are selected by transforming the emitted wavelength of the infrared laser, and absolute calibration is conducted on the thermal infrared hyperspectral imager through a characteristic wavelength spectrum calibration method. By means of the spectrum calibration system suitable for the thermal infrared hyperspectral imager, quick spectrum calibration of the thermal infrared hyperspectral imager with the high spectral resolution is achieved, and the spectrum calibration error value is smaller than 1 nm.

The device includes self-balanced current comparator, self-checking circuit, primary and secondary circuits and meter for measuring difference. After steps of self-checking, addition, comparison, measuring beta, and multiplication, absolute calibration of current scale is completed, and error of current scale of each self-balanced current comparator is obtained. Wiring is as following: H end of power source is connected to L1 end of comparator to be measured. L2 end and K2 end of comparator are connected to each other. K1 end of comparator to be measured through resistance is connected to ground end and L end of power source. Positive end of meter for measuring difference is connected to the said K2, and its negative end is connected to ground. The device is simple in structure and provides features of quick calibration and high efficiency.

The invention relates to a moon relative calibrating posture adjustment method by a remote sensing satellite, belonging to the moon imaging technology field and realizing the relative moon calibrating by the satellite. The moon relative calibrating posture adjustment method by a remote sensing satellite comprises steps of determining a relative calibration time quantum meeting the condition according to simulation, determining the speed of the satellite relative to the moon according to on-board orbit forecast data, determining an initial posture angle of the moon relative calibration by the satellite through double-vector posture fixation by combining a vector of a Z axis, along which the satellite is pointed to the moon, determining a posture angular velocity in the process of relatively calibration of the moon according to the anaylsis of the moon imaging parameter, eliminating the remote controller image displacement problem in the process of absolute calibration of the moon, determining the gesture angle of the relative calibration of the moon according to a gesture four element motion equation, and simulating and designing the satellite gesture track planning trace. The designing method of the invention can be applied in the moon relative calibration by the satellite.

The invention provides a time delay absolute calibration method for a multi-mode satellite navigation receiver. According to the method, firstly, a pseudorange measurement value outputted by the receiver is acquired; secondly, a 1PPS signal is reproduced through the receiver, and the actual output time delay is generated; and lastly, the time delay of the receiver is acquired. The absolute time delay of the receiver in different systems, different frequency bands and different pseudo-codes are fully calibrated through utilizing a satellite signal simulator, including the reception channel timedelay and the 1PPS link time delay, time delay deviation of the receiver under phase difference of different reference signals can be calibrated, the method is not only suitable for receivers in various types, and the method is further applicable to time delay calibration of navigation satellites and comprehensive base bands.

The invention provides a magnitude-phase absolute calibration device of a high-temperature vibration sensor. A cylindrical vibration extension rod is fixedly arranged above a standard vibration table, a calibrated sensor is arranged on the top end of the vibration extension rod, and the top of the vibration extension rod and the calibrated sensor are arranged in a high-temperature test chamber; a laser interferometer is arranged outside the high-temperature test chamber; a thermocouple or a platinum resistor is arranged in the high-temperature test chamber which is heated by a heating device; the calibrated sensor is connected with a conditioning amplifier outside the high-temperature test chamber through a high-temperature resistant signal line, and the conditioning amplifier is connected with a data acquisition card; the laser interferometer is connected with a photoelectric converter which is connected with the data acquisition card; the data acquisition card is connected with a computer; the standard vibration table is connected with a power amplifier which is connected with a signal source. According to the magnitude-phase absolute calibration device, the high-temperature test chamber is used for providing high temperature, and the laser interferometer is used as a vibration standard, so as to realize the calibration on sensitivity amplitude and phase of the vibration sensor at high temperature.

The present invention provides a vibration sensor high temperature sensitivity absolute calibration method. The method includes the following steps that: (1) a high temperature test box is set; (2) the vibration of a standard vibration stage is conveyed to a calibrated vibration sensor in the high temperature test box through a vibration extension rod, the vibration sensor in the high temperature test box senses the vibration signals of the standard vibration stage and generates analog electrical signals, and outputs the analog electrical signals to a data acquisition card, the analog electrical signals are converted into digital signals through the data acquisition card, and the digital signals are inputted to a computer; (3) light of a laser interferometer is emitted onto the calibrated vibration sensor through a glass window on the high temperature test box, the laser interferometer measures the vibration magnitude of the vibration sensor and outputs analog electrical signals, the analog electrical signals are converted into digital signals through the data acquisition card, and the digital signals are inputted to the computer; and (4) the computer calculates the high temperature sensitivity of the vibration sensor. With the vibration sensor high temperature sensitivity absolute calibration method of the invention adopted, the problem of incapability of calibrating a vibration sensor under a high temperature environment can be solved, and the high temperature sensitivity absolute calibration of the vibration sensor can be realized.

The invention discloses a detected lens mounting and adjusting method for spherical lens surface shape absolute calibration. In a spherical lens surface shape error absolute calibration process, the coordinate position of an optical axis of a detected lens in a surface shape interference detection result can be accurately positioned, so important guarantee is provided for high precision correction on a surface shape error of the detected lens, influence of a two-surface surface inclination processing error and a lens centering processing error of a traditional lens in the prior art is avoided, a problem that the coordination position of an optical axis of a detected lens in the surface shape detection result can not be accurately positioned in the prior art is solved. The invention further provides a detected lens mounting and adjusting device for spherical lens surface shape absolute calibration.

The invention relates to an absolute calibration method for a satellite radar altimeter without a special calibration field and belongs to the technical field of calibration of satellite altimeters. According to the method, an absolute deviation of the satellite radar altimeter can be determined through processing tidal observation data and satellite altimetry data of a satisfactory oceanographic station, adding essential correction entries such as a geoid model, carrying out height datum unification, altimetry data space position interpolation and tidal observation data time interpolation, and finally, carrying out difference comparison on sea surface height of tidal observation and sea surface height of the satellite radar altimeter. Compared with the prior art, the method has the advantages that the special calibration field is not required, the existing oceanographic stations can have calibration capability by using existing business observation data of oceanographic stations of coasts or oceanic islands of our country and a regional accurate geoid, and thus, absolute measured deviations of the satellite altimeters at home and abroad can be acquired.

The invention discloses an angular impact table for an excitation device for calibrating an angular motion sensor. The angular impact table comprises a master motion structure and a slave motion structure; the master motion structure comprises a worktable, a main motion shaft, a grating for measurement, a grating seat, a grating reading head, a shell, a main drive motor, an air floating shaft sleeve, a rigid coupling, a grating for control, a support seat, a base, a table body and an upper shield plate; and the slave motion structure comprises a sliding ring support, a coder rack, a motor rack, a slave drive motor, a rotor shaft, an angular contact ball bearing, a sliding ring, a sliding ring seat, a coder and a housing. By adopting the design method of the master and slave motion structures and the air floating shaft series in the main shaft, the interference of friction when the master motion body moves is reduced, and the accuracy of calibration is improved. Angular impact excitation mode and an absolute calibration method are adopted in the angular impact table, and a new method and a new means are provided for the calibration of the angular motion sensor.

The invention discloses a radiometer calibration method. On the basis of completing the absolute calibration of cold and heat sources by a 'four-point non-linear method', the 'relative calibration' process of 'noise calibration' and 'gain calibration' is executed periodically according to different abilities for maintaining stability by each parameter of the radiometer to acquire more accurate characteristic parameters of the radiometer and target observation data. By the method, the calibration and observation accuracy of the radiometer can be improved, the absolute calibration process of the cold and heat sources is not needed to be executed frequently, the requirement on operating environment is reduced greatly, the radiometer can complete periodic automatic calibration, and field application and unattended long-term operation can be realized.