International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / Since June of 1993, an experimental GPS receiver system has been orbiting the earth aboard a small, low-altitude, polar-orbiting satellite called RADCAL. The purpose of the experiment was to prove the concept of using GPS for satellite navigation. If successful, the system would also provide a backup to the satellite's primary navigation beacon. The goal: provide position and velocity data to an accuracy of three to five meters, and provide attitude data to within a degree. The configuration of the RADCAL GPS experiment precluded realtime feedback loops for navigation; the data was stored and downloaded after a designated collection period. On the ground, a lengthy process was used to yield the position and attitude data days after the collection event. The GPS receivers and ground equipment were configured in several modes; they ultimately yielded a position accuracy of five meters, and attitude of two degrees. This was the original goal, and the experiment was considered successful. However, one of the receivers failed in November 1993, and the other failed in January 1995. The GPS receivers were commercially available and not spaceflight proven; they were suspected of being vulnerable to single-event upsets and latchups. This turned out to be the cause of the failure of both receivers. The interface between the GPS receivers and RADCAL's other subsystems proved to be the area which could not tolerate corrupt data. The single-event latchups problems would ultimately lead to the failure of the receivers. These difficulties, as well as other lesser obstacles, provide a host of lessons learned for future satellite navigation systems.

Includes bibliographical references (p. 207-232) / xxii, 232 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Due to the rapid deployment of modern over-the-horizon radars, antenna/sensor position errors may be present and, since the antennas have a simple and cost-effective design, mutual coupling may also be present. These imperfections, which can degrade radar performance, form the basis of the investigation. Also calibrates the receiving array of the Jindalee over-the-horizon radar (located in Central Australia) using echoes from meteor trails. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1998

Table of corrections inserted opposite table of contents. / Bibliography: p.191-212. / xxiv, 212 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates calibration for errors of a synthetic aperture in Inverse Synthetic Aperture Radar and Multiple Pass Synthetic Aperture Radar. Both are reviewed as the problems of array processing and are solved from the point of array calibration. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 2000

Includes bibliographical references (p. 207-232) / xxii, 232 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Due to the rapid deployment of modern over-the-horizon radars, antenna/sensor position errors may be present and, since the antennas have a simple and cost-effective design, mutual coupling may also be present. These imperfections, which can degrade radar performance, form the basis of the investigation. Also calibrates the receiving array of the Jindalee over-the-horizon radar (located in Central Australia) using echoes from meteor trails. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1998

Table of corrections inserted opposite table of contents. Bibliography: p.191-212. Investigates calibration for errors of a synthetic aperture in Inverse Synthetic Aperture Radar and Multiple Pass Synthetic Aperture Radar. Both are reviewed as the problems of array processing and are solved from the point of array calibration.

<p dir="ltr">In this study we seek to evaluate the dry snow method of Z_DR calibration using dry snow as a target for X-band radars in comparison to vertical calibration scans. Numerous dates in the 2021 year were analyzed using the X-band Teaching and Research Radar (XTRRA) located on the Purdue University campus utilizing both vertical scans and azimuthal scans of dry snow. It was found that dry snow is still a potentially viable X-band calibration but several caveats, such as significant impacts from the protective dome around the radar, need to be addressed in order to make these results more robust.</p>

International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / An increasing number of satellite users and manufacturers are looking to lightweight, inexpensive satellites as substitutes to traditional large, expensive satellites with multiple payloads. Neither the Department of Defense nor the commercial sector can bear the financial or reputational consequences associated with massive program failures. With the low cost and weight of these new satellites, users can achieve mission success without great risk. One example of this new class of inexpensive spacecraft is the RADCAL (RADar CALibration) satellite. Detachment 2, Space & Missile Systems Center at Sunnyvale, CA operates the satellite. RADCAL is a 200-pound polar orbiting satellite with an average altitude of 450 miles. It is primarily used by 77 worldwide radars to calibrate their systems to within five meter accuracy. Also flying on board RADCAL is a communication payload for remote field users with small radios. The RADCAL program has satisfied all mission requirements. However, with the limited size and cost come certain challenges, both in the satellite and on the ground. Pre-launch testing was not as comprehensive as with more expensive programs; anomalies have arisen that require extensive workarounds. Data management is not a straightforward task, and it is sometimes difficult and inexact to track satellite performance. These challenges are presented with their solutions in the following discussion; this paper addresses the functional, operational, and testing aspects associated with the RADCAL satellite.

"November 2004" / Includes bibliographical references (leaves 283-293) / xxix, 293 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Electrical and Electronic Engineering, 2004

Die Nutzung von Riometern (Relative Ionospheric Opacity Meter) zur Messung relativer atmosphärischer Absorption (in dB) ist eine etablierte Methode. Hingegen ist die Messung atmosphärischer Absorption mit absolutkalibrierten Radaren in Form einer Rauschtemperatur eher selten durchgeführt worden. In dieser Arbeit werden die Möglichkeiten einer absoluten Radarkalibrierung für ein kommerzielles SKiYMET-System vorgestellt. Die gemessene QDC (Quiet Day Curve, eine Referenzkurve für ungestörte Tage) wird dabei mit Referenzdaten verglichen. Daran wird der Einfluss des Antennenmusters auf die QDC verdeutlicht und quantitativ dargestellt. Die erreichte Genauigkeit beträgt dabei ungefähr 600 K. Die kontinuierliche und stabile Beobachtung erlaubt es, die Kopplung der Ionosphäre mit der solaren Aktivität zu untersuchen, ohne den normalen Betrieb zur Meteoranalyse zu unterbrechen. / The observation of relative atmospheric absorption (in dB) using Riometers (Relative Ionospheric Opacity Meter) is a well established method. However, the measurement of atmospheric absorption as a noise temperature with absolutely calibrated radars has rarely been realized. This work demonstrates the possibilities to perform an absolute radar calibration for standard SKiYMET meteor radars. The measured QDC (Quiet Day Curve) and the comparison to a reference QDC illustrates the capability to quantify the effect of the antenna pattern. The achieved accuracy for a QDC is approximately 600 K. The high stability of the observation during normal meteor mode allows also to investigate the ionospheric response caused by the coupling of the solar activity.

The NASA Scatterometer (NSCAT) was launched August 20, 1996 aboard the National Space Development Agency of Japan's Advanced Earth Observing Spacecraft (ADEOS). NSCAT's primary mission was to measure radar backscatter over the world's oceans. These measurements are used to generate estimates of ocean wind speed and direction. Scatterometers must be calibrated before their measurements are scientifically useful. However, the calibration of NSCAT must be done in orbit. A new methodology for selecting land regions for use in extended target spaceborne scatterometer calibration is first developed. Next, a summary of the calibration technique used in this thesis is presented. While the foundation of this technique was previously developed theoretically, the work in this thesis is its first application for calibration/validation of an on-line spaceborne radar system. The technique is extended to estimate simultaneously NSCAT's calibration and the host spacecraft's attitude error. The attitude references reported by the attitude control system on-board ADEOS are deemed erroneous. Results of this expanded technique, applied under varying assumptions, are presented for consideration. A summary and suggestions for future research conclude this work.