Article

GEOS-C C-band transponder prelaunch calibration and test data

February 1976

Authors:

The delay characteristics and spacecraft telemetry housekeeping data for the GEOS-C C-Band transponders are presented. The data are presented in graphical form to provide a convenient method for computing radar range measurement corrections as a function of signal strength at the transponder and spacecraft environment. The data are also presented in tabular form along with the mathematical models used to derive the curves. Also included are a list of the operating characteristics of each transponder and a description of the calibration test equipment set-up.

ResearchGate has not been able to resolve any citations for this publication.

GEOS-C Telemetry Function Calibrations. Viemorandum S2T-1-337

Oct 1974

M R Peterson

Peterson, M.R.; GEOS-C Telemetry Function Calibrations. Viemorandum S2T-1-337, Applied Physics Laboratory of the Johns Hopkins University, October 1974,

Article

Demonstration of an improved calibration scheme for ERS-1 SAR imagery using a scatterometer wind mod...

January 1995 · International Journal of Remote Sensing

The importance of an improved calibration scheme for the derivation of the normalized radar cross-section coefficient σ0 for distributed targets using ERS-1 SAR imagery is assessed. The improved calibration scheme includes corrections relating to the saturation of the on-board Analogue to Digital Convenor (ADC) and to variations in the replica pulse power. The significance and effectiveness of ... [Show full abstract] the additional corrections is demonstrated by comparing the range variation of σ0 from 10 ERS-1.SAR.PRI images of the English Channel with that predicted by the CMOD4 scatterometer wind model. Close agreement is found at all range positions, provided the additional corrections are applied.

Conference Paper

An improved adaptive correction method for camera distortion

July 2014

This paper is concerned with the problem of camera distortion, and it presents a method with short computing time and high calibration accuracy, which can be easily achieved and adaptable to online distortion correction. By introducing adaptive iterative process this method could correct the camera distortion in real time. The method firstly applies the adaptive iterative process on the ... [Show full abstract] distortion model and corrects each feature points separately to get the distortion coefficients of each feature points. And then it utilizes the bilinear interpolation method and applies the corrected model on the distortion images. Finally, simulation results demonstrate the advantages of the proposed method.

Conference Paper

An Assessment of the Icing Blade and the SEA Multi-Element Sensor for Liquid Water Content Calibrati...

June 2016

The Icing Research Tunnel at NASA Glenn has recently switched to from using the Icing Blade to using the SEA Multi-Element Sensor (also known as the multi-wire) for its calibration of cloud liquid water content. In order to perform this transition, tests were completed to compare the Multi-Element Sensor to the Icing Blade, particularly with respect to liquid water content, airspeed, and drop ... [Show full abstract] size. The two instruments were found to compare well for the majority of Appendix C conditions. However, it was discovered that the Icing Blade under-measures when the conditions approach the Ludlam Limit. This paper also describes data processing procedures for the Multi-Element Sensor in the IRT, including collection efficiency corrections, mounting underneath a splitter plate, and correcting for a jump in the compensation wire power. Further data is presented to describe the repeatability of the IRT with the Multi-Element sensor, health-monitoring checks for the instrument, and a sensing-element configuration comparison.

Conference Paper

Using variational approach and spectrometry-specific criteria for calibration of spectrometric syste...

February 1996

The problem addressed in this paper is related to numerical correction of spectrometric data aimed at improving the resolution of spectrometric analyses. An idea of weighted optimization is put forward and examined with respect to its power of spectrogram interpretation

Article

Far-field radar cross section determination using near-field ISAR imaging techniques

January 2006

Inverse synthetic aperture radar (ISAR) imaging is a powerful tool for the characterization of radar targets. Since the direct determination of the far-field radar cross section (RCS) typically requires expensive arrangements and equipment, short distance ISAR imaging of the radar targets has been proposed as alternative method, where the resulting near-field images can be used to extract the ... [Show full abstract] far-field radar cross section of the target. This contribution compares the performance of different near-field imaging techniques together with a new approach and accuracy improvements. Furthermore, a detailed insight in the imaging process is given, leading to reliable sampling rules, thus together with calibration and focusing techniques a complete concept for accurate far-field RCS extraction is given.

Conference Paper

One-shot scanning method using an unealibrated projector and camera system

July 2010

In this paper, we describe a new one-shot scanning technique using a camera and a projector. Generally, a 3D measurement system based on a camera and a projector requires pre-calibration, such as the measurement of the relative position of these devices. If we can eliminate the calibration process, it would greatly improve the convenience of the system. For example, a single capture by a ... [Show full abstract] hand-held camera of an object illuminated by a hand-held projector would then allow to reconstruct the object shape. To achieve this, we propose a self-calibration technique using a projected grid pattern, computing the relative pose of projector and camera. This is similar to the relative pose or motion problem for two cameras, but in our case correspondences are not explicitly given. The actual algorithm is based on a simple exhaustive search of a finite set of hypotheses, with a cost function based on the epipolar constraint. In the experiments, successful reconstructions with our proposed method using synthetic and read data are presented.

Article

Utilization of Concurrently Gathered Pulser Data for Complete Spectral Validation of Gamma-Ray Spect...

March 1981 · IEEE Transactions on Nuclear Science

Some of the capabilities and limitations of using concurrently gathered pulser data for energy calibration, dead time correction, and pile-up loss correction of gamma ray spectra from germanium detectors have been investigated. This report deals with the pulser, charge injection into the charge sensitive preamplifier, hardware separation of gamma and pulser events, and analysis techniques to ... [Show full abstract] improve the accuracy of gamma peak area corrections from pulser data. Data is presented indicating achievable short and long term energy calibration stability of better than .01% and accuracy of rate dependent peak area loss corrections of +1% up to 50,000 pulses per second (pps) and +2.5% up to 100,000 pps, energy i ndependent.

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Distortion calibration of parallel screw thread form based on non-contact measurement

October 2011 · Nongye Jixie Xuebao/Transactions of the Chinese Society of Agricultural Machinery

Thread form showed distortion when measuring parallel screw thread parameters by using non-contact method. The traditional way had some defects, such as time consuming, skilled operator, high-precision equipment for adjustment and so on. Hence, a method through digital image calibration was presented. Based on the thread geometrical principle, the mathematical model was given out. With the above ... [Show full abstract] thread mathematic model, images obtained from camera were corrected and real thread form could be got. With the results of related experiments and simulation, the mathematic model was certified. This proposed method could improve accuracy and efficiency of thread measurement and detection.

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Metric Accuracy Improvements of Space-Based Visible Using Spacecraft Attitude Drift Corrections

January 2000 · Journal of Guidance, Control, and Dynamics

The Midcourse Space Experiment satellite, sponsored by the Ballistic Missile Defense Organization, was launched in April 1996 into an 898-km altitude, near sun-synchronous orbit. One of the principal sensors onboard the spacecraft is the Space-Based Visible, a visible-band, electro-optical camera designed to perform the first technical and functional demonstration of space-based space ... [Show full abstract] surveillance. The principal task of the Space-Based Visible is to gather metric and photometric information on a wide variety of resident space objects. To assess the metric performance of the sensor, routine on-orbit metric calibration is performed. In addition, a complete independent error assessment was made using actual flight data. The goal of producing 4-arc-s (1-sigma) observations of resident space objects was set during design, and results show that this goal is being met. A method is presented that improves the metric observations of resident space objects to better than 2-arc-s (1-sigma) by estimating the drift of the spacecraft attitude during staring events and removing the effect from the observations. Compensating for this error source brings into agreement the results of on-orbit calibration and the independent error assessment.

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A new recognition method for subsurface targets based on ground penetrating radar map

January 2011 · International Journal of Digital Content Technology and its Applications

In this paper, we proposed a punctuated target identification method for underground homogeneous medium based on dielectric constant inversion algorithm. Its main idea is that, initially, Hough transform is used to locate the target characterized by hyperbola in a radar profile map, then a layer-by-layer waveform inversion algorithm is used to invert the dielectric constant on the location where ... [Show full abstract] the target lies. To guarantee the correctness of inversion, the transmission beam method is adopted to obtain initial parameters and calibration factors required by inversion. Through numerical analysis of the dielectric constant of the target, the classification of multiple targets in an underground medium can be confirmed. This method not only overcomes the failure of the traditional phase-comparison method to distinguish different kinds of targets in the same region, but also overcomes the limitation of the image processing method, in which it only classifies the target in a coarse-grained manner. Experimental results show that this method has many advantages, such as fine grained classification, high precision, and capability of multiple targets identification for the identification of subsurface targets.

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Analysis and Correction of Time Delay Active Radar Calibrator Imaging for High-resolution SAR

February 2012 · JOURNAL OF ELECTRONICS INFORMATION TECHNOLOGY

Time delay Active Radar Calibrator (ARC) is the crucial equipment for image quality evaluation and radiation calibration of Synthetic Aperture Radar (SAR). The technique of time delay in ARC will reduce the influence of local noise and improve the measure precision. However, the image quality of time delay ARC will be influenced inevitably, especially for high-resolution SAR. In this paper, the ... [Show full abstract] analysis model for image quality influence of ARC induced by time delay for high-resolution SAR is established. The effects induced by different time delay, including peak power, 3 dB width of main lobe, Peak Side Lobe Ratio (PSLR) and Integrated Side Lobe Ratio (ISLR) are analyzed quantificationally. A correction method of time delay is proposed, and the validity of the method is proved through simulation.

Article

A method for the production of acoustic forecasts using a digital computer

December 1978

R. T. Suggitt

Acoustic forecasts are provided by three upper-air stations in the United Kingdom for the prediction of the propagation of noise from gunfire and other surface detonations. In the near future the stations will be equipped with the new United Kingdom Mk 3 radiosonde system. In addition to the new radiosonde and new receiving and recording devices, each upper-air station will have a minicomputer. ... [Show full abstract] The computer is used during a radiosonde ascent to sample the coded data that are transmitted by the radiosonde, to apply quality control and calibration corrections to the data, to decode them, and to select from them the significant temperature and humidity values. The computer interrogates a radar and uses the sets of azimuth, elevation, and slant range obtained to derive a wind profile for the ascent. Attention is given to the production of sound foci, the model which is used in the calculation of acoustic forecasting data, and a number of model refinements.