Study of radar pulse compression for high resolution satellite altimetry

Pulse compression techniques are studied which are applicable to a satellite altimeter having a topographic resolution of + 10 cm. A systematic design procedure is used to determine the system parameters. The performance of an optimum, maximum likelihood processor is analysed, which provides the basis for modifying the standard split-gate tracker to achieve improved performance. Bandwidth considerations lead to the recommendation of a full deramp STRETCH pulse compression technique followed by an analog filter bank to separate range returns. The implementation of the recommended technique is examined

U.S. Law of the Sea Cruise to Complete the Mapping of Necker Ridge, Central Pacific Ocean

U.S. Law of the Sea Cruise to Complete the Mapping of Necker Ridge, Central Pacific Ocean CRUISE KM1121 July 31, to August 10, 2011 Honolulu, HI to Honolulu, H

The QUIET Instrument

The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting the imprint of inflationary gravitational waves at large angular scales (~ 1 degree). Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4 m side-fed Dragonian telescope. The polarimeters which form the focal planes use a highly compact design based on High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U, and I in a single module. The 17-element Q-band polarimeter array, with a central frequency of 43.1 GHz, has the best sensitivity (69 uK sqrt(s)) and the lowest instrumental systematic errors ever achieved in this band, contributing to the tensor-to-scalar ratio at r < 0.1. The 84-element W-band polarimeter array has a sensitivity of 87 uK sqrt(s) at a central frequency of 94.5 GHz. It has the lowest systematic errors to date, contributing at r < 0.01. The two arrays together cover multipoles in the range l= 25-975. These are the largest HEMT-based arrays deployed to date. This article describes the design, calibration, performance of, and sources of systematic error for the instrument

Broadband Echosounder Calibration and Processing for Frequency Dependent Target Strength and Phase Measurements

An analysis technique is developed for the calibration and processing for the target strength and phase spectra using a broadband echosounder. A new variable ‘residual phase’ is introduced, which could be used as a target classifier. Implementation of the method to characterise marine organism from the open ocean, demonstrated consistent target strength and residual phase and the matching of both the variables to the output of the numerical scattering model verified the method

Spaceborne synthetic aperture radar pilot study

A pilot study of a spaceborne sidelooking radar is summarized. The results of the system trade studies are given along with the electrical parameters for the proposed subsystems. The mechanical aspects, packaging, thermal control and dynamics of the proposed design are presented. Details of the data processor are given. A system is described that allows the data from a pass over the U. S. to be in hard copy form within two hours. Also included are the proposed schedule, work breakdown structure, and cost estimate

An improved rocket-borne electric field meter for the middle atmosphere

Improvements in a rocketborne electric field meter designed to measure the atmosphere's electric field and conductivity in the middle atmosphere are described. The general background of the experiment is given as well as changes in the instrument and data processing schemes. Calibration and testing procedures are documented together with suggestions for future work

An investigation into the use of orthogonal frequency division multiplexing in packet radio

Bibliography: leaves 56-58.The concept of Orthogonal Frequency Division Multiplexing has been around since the 1960s. It has resurfaced over the last decade as being the modulation scheme of choice in some newer technologies like Digital Video Broadcasting (DVB) and Asynchronous Digital Subscriber lines (ADSL). Amateur packet radio started in 1978 and has attracted thousands of enthusiasts from around the world. The interest in packet radio has waned over the years due advances in the data transmission capabilities oflandline systems and also more widespread access to the Internet. The purpose of this thesis was to develop a simple software simulation model to determine whether or not OFDM could be used to increase the data rates currently available in packet radio systems. The thesis starts out with an introduction to packet radio and OFDM in Chapter 1. A slightly more detailed discussion on OFDM is given in Chapter 2 in order to develop a basic specification for the proposed OFDM model. Chapters 2,3 and 4 discuss the development of the Transmitter model, the Receiver model and the Channel model respectively using the Simulink software package. Chapter 6 discusses the problem of Peak-to-Average Power Ratios (PAPR) in OFDM and explores the use of A-law companding to reduce this problem. In Chapter 7, the developed models are simulated and their performance compared to theoretical expectations. The full system is also simulated in this chapter in order to ascertain the possible data rate through the modelled packet radio channel. Conclusions regarding the application of OFDM to packet radio are presented in Chapter 8

The application of air-coupled ultrasonic systems and signal processing to the interrogation of concrete

This thesis describes the application of ultrasound to the interrogation of concrete for the retrieval of quantitative information. In particular the use of air-coupled ultrasound is applied for the first time with recent improvement in ultrasonic technology making this possible. Broadband capacitance transducers are used in tandem with pulse compression to deliver and receive ultrasonic signals with greatly improved SNR’s. Pulse compression involves the cross correlation of a chirp signal to record accurate ultrasonic time of flights. This metric is used to makes structural inferences about concrete and to compare contact and non-contact ultrasonic systems. This comparison reveals that concrete strength estimation from ultrasonic pulse velocity (UPV), alone is inaccurate. Other metrics such as aggregate content and humidity should also be considered. A study in to the effect of humidity on the UPV is presented and a correction factor obtained that normalises UPV around a humidity that could be considered normal to a temperate climate. Images of reinforcement bars embedded in concrete are presented using the pulse compression technique. Time-frequency (t-f) analysis is applied to ultrasonic chirp signals. Extensive simulation is carried out and a comparison between three different methods presented. This ensures accurate tracking of the ultrasonic chirp signals, which allows for frequency scattering to be examined. T-f analysis is then applied to real ultrasonic signals and it is shown how frequencies spectrums of received chirps can be de-noised using the Hough transform. Images of embedded defects are then presented. The Superheterodyne technique is then described and applied to concrete interrogation. Although not overly successful it is shown how energy distributions of received tone burst signals vary with time and the need for further work is discussed