DOCSLIB.ORG

T066% -368 F 2060 2

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
T066% -368 F 2060 2 t066% -368 f 2060_2 ANALYSIS OF AIRBORNE RADAR ALTIMETRY MEASUREMENTS OF THE GREENLAND ICE SHEET A Dissertation Presented by ELLEN J. FERRARO Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY May 1994 Department of Electrical and Computer Engineering (_) Copyright Ellen J. Ferraro 1994 All Bights Reserved ANALYSIS OF AIRBORNE RADAR ALTIMETRY MEASUREMENTS OF THE GREENLAND ICE SHEET A DissertationPresented by ELLEN J. FERRARO A_content by: Calvin T. Swift,Chair Robert E. McIntosh, Member. Patrick A. Kelly, Member (_/ J_gham_.grctte, Member • ver, Department Head . Electrical& Computer Engineering To Morn and Dad ACKNOWLEDGMENTS During my graduate school years, I have had the invaluable opportunity to not only study microwave remote sensing of the earth, but also to design and manage a project from its development through to its final stages of experiment and data analysis. As my advisor, Dr. CMvin T. Swift allowed me to make my own decisions as well as make my own mistakes, while providing the guidance and encouragement necessary as I progressed from a shy and naive first year graduate student to a doctoral recipient. I would like to thank him for this guidance and for the opportunity to travel to unique places such as Greenland, Iceland and Newfoundland. Both Dr. Calvin T. Swift and Dr. Robert E. Mclntosh deserve thanks for providing the exce]]ent facilities and equipment available in the Microwave Remote Sensing Laboratory, without which none of this work would have been possible. I would also like to thank Dr. Patrick Kelly for serving on my committee and Dr. Julie Brigham-Grette for her help in preparing for my trip to Greenland and for serving on my committee. When the design for the refurbished AAFE altimeter was first being developed, Dr. Chris Rapley, Dr. Seymour Laxon and many other scientists at the Mullard Space Science Laboratory provided invaluable suggestions on current tracking tech- niques and problems with previous tracking methods, as we]] as a tremendous amount of literature on radar altimetry. Once the AAFE system was completely developed I spent numerous hours at the NASA Wallops Flight Facility installing and testing the instrument. I would like to thank the aircraft crew and pilots at Wallops for their assistance and friendship. In addition I would like to thank the Observational Sciences Branch_ especially Bill Krabil] and Earl Frederick for their V patience and help in providing GPS, AOL and INS data and for their friendship. Everyone at Wallops knew how to make a Yankee feel welcome and comfortable on the eastern shore of Virginia. During my last summer in MIRSL, I spent four weeks on the Greenland ice cap. Despite inhibitions about camping on an ice sheet without heat or hot water, it turned out to be a fun and adventure-some experience, primarily due to the help and friendship of Ingrid Zabel, Paul Baggeroer, Henry Brecher, Mark Anderson and Clint Rowe. I would especially like to thank Clint Rowe and Mark Anderson for their help in the probing experiment. I would also like to thank Dr. Robert Thomas for providing the funding for this project under NASA grant NCT-50606, Matthew Grund for operating the AAFE altimeter during the 1993 experiment, Wayne Boncyk for his help in developing the data acquisition system of the radar and the numerous other past and present MIRSL graduate students whose suggestions, help and friendship aided in the devel- opment of this project. In addition, I would like to thank Claire Hopley for reading and editing this dissertation. There are many people who helped me through the difficult times in both undergraduate and graduate school, but the person that deserves the most thanks is Dean Nancy HeUman for her encouragement, guidance and friendship. Finally, I would like to thank my friends and family, especially my parents Neal and Bernice Martin, for their love and support throughout the past twenty-six years. I love all of you and none of this would have been worth while if it were not for the opportunities to go home and share these experiences with you. Above all, I thank my husband and friend for life, Paul Ferraro, for his love, his support and for the lifetime that we will share together. vi ABSTRACT ANALYSIS OF AIRBORNE RADAR ALTIMETRY MEASUREMENTS OF THE GREENLAND ICE SHEET MAY 1994 ELLEN J. FERRARO B.S.E.E., UNIVERSITY OF MASSACHUSETTS AMHERST PH.D._ UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Calvin T. Swift This dissertation presents an analysis of airborne altimetry measurements taken over the Greenland ice sheet with the 13.9 GHz Advanced Apphcation Fhght Ex- periment (AAFE) pulse compression radar altimeter. This Ku-band instrument was refurbished in 1990 by the Microwave Remote Sensing Laboratory at the University of Massachusetts to obtain high-resolution altitude measurements and to improve the tracking, speed, storage and display capabilities of the radar. In 1991 and 1993, the AAFE altimeter took part in the NASA Multisensor Airborne Altimetry Experiments over Greenland, along with two NASA laser altimeters. Altitude results from both experiments are presented along with comparisons to the laser altimeter and calibration passes over the SondrestrSm runway in Greenland. Although it is too early to make a conclusion about the growth or decay of the ice sheet, these results show that the instrument is capable of measuring small-scale surface changes to within 14 centimeters. In addition, results from these experiments reveal that the radar is sensitive to the different diagenetic regions of the ice sheet. Return waveforms from the wet- snow, percolation and dry-snow zones show varying effects of both surface scattering and sub-surface or volume scattering. Models of each of the diagenetic regions of Greenland are presented along with parameters such as rms surface roughness, rms vii surface slopeand attenuation coetTicient of the snow pack obtained by fitting the models to actual return waveforms. °oo Vlll TABLE OF CONTENTS P _st ACKNOWLEDGMENTS ........................................ v ABSTRACT ................................................ vii LIST OF TABLES ........................................... xi LIST OF FIGURES ........................................... xii CHAPTERS I. INTRODUCTION ........................................... 1 i.I History of Radar Altimetry ....................... 1 1.2 Scientific Motivation ........................... 2 1.3 Summary of Chapters .......................... 4 2. PRINCIPLES OF RADAR ALTIMETRY ........................... 6 2.1 Altitude Measurements ......................... 6 2.2 Pulse compression ............................ 8 2.3 Mode of Operation ........................... 16 3. AAFE RADAR ALTIMETER SYSTEM ........................... 24 3.1 Radar System Hardware ........................ 25 3.1.1 Transmitter Subsystem ..................... 28 3.1.2 Antenna ............................. 31 3.1.3 Receiver Subsystem ....................... 31 3.1.4 Data Acquisition Subsystem .................. 36 3.1.5 Tracking Subsystem ....................... 40 3.1.6 Control Subsystem ....................... 47 3.2 System Calibration ........................... 49 3.2.1 Internal Calibration ....................... 49 3.2.2 External Calibration ....................... 55 3.3 Noise Analysis .............................. 55 3.3.1 System Signal-To-Noise Ratio ................. 55 3.3.2 Range Resolution ........................ 66 3.3.3 Quantization Noise ....................... 69 3.3.4 FFT Errors ............................ 69 ix 4. ALTIMETRYMEASUREMENTSOF THE GREENLAND ICE SHEET ........ 71 4.1 1991 Greenland Experiment ...................... 71 4.1.1 Experiment Description and Fhght Lines ........... 71 4.1.2 Runway Ground Truth Comparison .............. 72 4.1.3 Comparison with the AOL Laser Altimeter .......... 78 4.1.4 Comparison of Flight Line Cross-over Points ......... 88 4.1.5 Altitude Results ......................... 90 4.2 1993 Greenland Experiment ...................... 93 4.2.1 Experiment Description and Fhght Lines ........... 93 4.2.2 Runway Ground Truth Comparison .............. 98 4.2.3 Altitude Results ......................... 98 4.3 Comparison of 1991 and 1993 Elevation Measurements ........ 101 5. ANALYSIS OF WAVEFORMS FROM THE GREENLAND ICE SHEET ....... 106 5.1 Scattering Models of the Diagenetic Zones of Greenland ....... 110 5.1.1 Wet-snow Zone Model ...................... 110 5.1.2 Percolation Zone Model ..................... 120 5.1.3 Dry-snow Zone Model ...................... 132 5.2 Mapping Diagenetic Zones ....................... 144 5.3 Comparison of Retracking Algorithms ................. 148 6. CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE RESEARCH ..... 159 REFERENCES .............................................. 161 X LIST OF TABLES Table Page 3.1 Table of AAFE parameters used to calculate the system signal-to- noise ratio .................................. 64 5.1 Table of the five parameters used in the least-mean-squared error fit to the surface scattering model ...................... 115 5.2 Table of the seven parameters used in the LMSE fit to the combined surface and Rayleigh volume scattering model .............. 140 5.3 Table of the five parameters used in the least-mean-squared error fit to the Martin et al. model ......................... 151 xi LIST OF FIGURES Figure Page 2.1 Principle of a radar altimeter altitude measurement ........... 7 2.2 Example of a
Load more

Recommended publications
  • Spring 2017 Some Reflections on the History of Radar from Its Invention
    newsletter OF THE James Clerk Maxwell Foundation ISSN 205 8-7503 (Print) Issue No.8 Spring 2017 ISSN 205 8-7511 (Online) Some Re flections on the History of Radar from its Invention up to the Second World War By Professor Hugh Griffiths , DSc(Eng), FIET, FIEEE, FREng, University College, London, Royal Academy of Engineering Chair of Radio Frequency Sensors Electromagnetic Waves – Maxwell and Hertz In 1927, in France, Pierre David had observed similar effects and, in 1930, had conducted further trials, leading to a deployed In his famous 1865 paper ‘ A Dynamical Theory of the Electromagnetic forward-scatter radar system to protect the naval ports of Brest, Field’ Maxwell derived theoretically his famous equations of Cherbourg, Toulon and Bizerte (Algeria). electromagnetism which showed that these equations implied that electromagnetic disturbances travelled as waves at finite speed. In 1935, in the UK, Robert Watson-Watt had a claim to be From the fact that the speed of these waves was equal (to within ‘the father of radar’ on the basis of the Daventry Experiment experimental error) to the known velocity of light, Maxwell (described later in this article) and his development of a radar detection system (Chain Home) for the R.A.F. in World War II. concluded with the immortal words: “This velocity is so nearly that of light that it seems we have strong reason But, to the author, the priority for the invention of radar should go to conclude that light itself (including radiant heat and other radiations if to a German, Christian Hülsmeyer, a young engineer who in 1904 built and demonstrated a device to detect ships.
    [Show full text]
  • Quantification of Bird Migration Using Doppler Weather Surveillance Radars
    A Thesis entitled Quantification of Bird Migration Using Doppler Weather Surveillance Radars (NEXRAD) by Priyadarsini Komatineni Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Electrical Engineering Dr. Mohsin M. Jamali, Committee Chair Dr. Junghwan Kim, Committee Member Dr. Peter V. Gorsevski, Committee Member Dr. Patricia R. Komuniecki, Dean College of Graduate Studies The University of Toledo August 2012 Copyright 2012, Priyadarsini Komatineni This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author. An Abstract of Quantification of Bird Migration Using Doppler Weather Surveillance Radars (NEXRAD) by Priyadarsini Komatineni Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Electrical Engineering and Computer Science The University of Toledo August 2012 Wind Energy is an important renewable source in United States. Since past few years, the growth of wind farms construction has significantly increased, due to which there is an increase in number of bird deaths. Therefore, ornithologists began to study the bird’s behavior during different migration periods. So far ornithologists have used many methods to study the bird migration patterns in which the radar ornithology has been used in an innovative way. However, many studies have focused using small portable radars and recently researchers have proved that the migration events can be studied through large broad scale radars like NEXRAD. Throughout the United States, NEXRAD has 160 Doppler Weather Surveillance Radars. The advantage of NEXRAD is that it can provide bird migration movements over a broad geographical scale and can be accessed free of charge.
    [Show full text]
  • Radar Applications 1
    CHAPTER Radar Applications 1 William L. Melvin, Ph.D., and James A. Scheer, Georgia Institute of Technology, Atlanta, GA Chapter Outline 1.1 Introduction . .................................................... 1 1.2 Historical Perspective. ............................................ 2 1.3 Radar Measurements . ............................................ 5 1.4 Radar Frequencies................................................. 6 1.5 Radar Functions................................................... 8 1.6 U.S. Military Radar Nomenclature ..................................... 9 1.7 Topics in Radar Applications ......................................... 10 1.8 Comments . .................................................... 14 1.9 References. .................................................... 15 1.1 INTRODUCTION Radio detection and ranging (radar) involves the transmission of an electromagnetic wave to a potential object of interest, scattering of the wave by the object, receipt of the scattered energy at the receive site, and signal processing applied to the received signal to generate the desired information product. Originally developed to detect enemy aircraft during World War II, radar has through the years shown diverse application, not just for military consumers, but also for commercial customers. Radar systems are still used to detect enemy aircraft, but they also keep commercial air routes safe, detect speeding vehicles on highways, image polar ice caps, assess deforestation in rain forests from satellite platforms, and image objects under foliage or behind walls. A number of other radar applications abound. This book is the third in a series. Principles of Modern Radar: Basic Principles, appearing in 2010, discusses the fundamentals of radar operation, key radar subsystems, and basic radar signal processing [1]. Principles of Modern Radar: Advanced Techni- ques, released in 2012, primarily focuses on advanced signal processing, waveform design and analysis, and antenna techniques driving tremendous performance gains in radar system capability [2].
    [Show full text]
  • The History of Radar
    The Hi st or y of Canewdon Chai n Ho me 8th September 2013 Introduction Chain Home was the UK’s World War II long range Radar System It played a major part in winning the Battle of Britain One of the radar sites was here at Canewdon And one of Canewdon’s 360’ steel transmitter towers is now located at Chelmsford Keep watching to find out about Chain Home and why one of the Canewdon towers was moved 8th September 2013 Introduction • In 1932 Stanley Baldwin gives a speech to Parliament in which he states: “The Bomber Will Always Get Through” • He was not wrong, aircraft technology was improving and for the first time bomber aircraft were faster than fighters 8th September 2013 Introduction On the 2nd August 1934 Hitler becomes Germany’s head of state. He makes no secret that he wants to expand Germany’s borders. He starts to build up Germanys armed forces which is expressly forbidden under the terms of the treaty of Versailles. No European country is able or prepared to stop Germany. Some UK politicians think war is inevitable. 8th September 2013 The UK’s Air Defense Strategy – 1930 to 1935 • Early 1930’s • UK’s Air Defence Strategy • Mainstay was Royal Observer Corps formed in 1928 • Who used Optical, Infrared and Acoustic detectors to warn of approaching aircraft • Unfortunately they all suffered from: • Poor sensitivity • Limited range and were weather dependant Acoustic Detector 8th September 2013 The UK’s Air Defense Strategy – 1930 to 1935 • Acoustic Detectors - Sound Mirrors • The Sound Mirror was at the pinnacle of Acoustic Detection,
    [Show full text]
  • Cavity Magnetron 1 Cavity Magnetron
    Cavity magnetron 1 Cavity magnetron The cavity magnetron is a high-powered vacuum tube that generates microwaves using the interaction of a stream of electrons with a magnetic field. The 'resonant' cavity magnetron variant of the earlier magnetron tube was invented by John Randall and Harry Boot in 1940 at the University of Birmingham, England.[1] The high power of pulses from the cavity magnetron made centimeter-band radar practical, with shorter wavelength radars allowing detection of smaller objects. The compact cavity magnetron tube drastically reduced the size of radar sets[2] so that they could be installed in anti-submarine aircraft[3] and Magnetron with section removed to exhibit the escort ships.[2] At present, cavity magnetrons are commonly used in cavities. The cathode in the center is not visible. The waveguide emitting microwaves is at the left. microwave ovens and in various radar applications.[4] The magnet producing a field parallel to the long axis of the device is not shown. Construction and operation All cavity magnetrons consist of a hot cathode with a high (continuous or pulsed) negative potential created by a high-voltage, direct-current power supply. The cathode is built into the center of an evacuated, lobed, circular chamber. A magnetic field parallel to the filament is imposed by a permanent magnet. The magnetic field causes the electrons, attracted to the (relatively) positive outer part of the chamber, to spiral outward in a circular path rather, a consequence of the Lorentz force. Spaced around the rim of the chamber are cylindrical A similar magnetron with a different section cavities.
    [Show full text]
  • World War II Technology That Changed Warfare - Radar and Bombsights Sean Foley Johnson & Wales University - Providence, [email protected]
    Johnson & Wales University ScholarsArchive@JWU Academic Symposium of Undergraduate College of Arts & Sciences Scholarship 2-2011 World War II Technology that Changed Warfare - Radar and Bombsights Sean Foley Johnson & Wales University - Providence, [email protected] Follow this and additional works at: https://scholarsarchive.jwu.edu/ac_symposium Part of the Arts and Humanities Commons, Physical Sciences and Mathematics Commons, and the Social and Behavioral Sciences Commons Repository Citation Foley, Sean, "World War II Technology that Changed Warfare - Radar and Bombsights" (2011). Academic Symposium of Undergraduate Scholarship. 8. https://scholarsarchive.jwu.edu/ac_symposium/8 This Presentation is brought to you for free and open access by the College of Arts & Sciences at ScholarsArchive@JWU. It has been accepted for inclusion in Academic Symposium of Undergraduate Scholarship by an authorized administrator of ScholarsArchive@JWU. For more information, please contact [email protected]. World War II Technology that Changed Aviation Warfare Radar and Bombsights http://steveblank.files.wordpress.com/2009/04/wurzburg-reise-radar.jpg http://farm2.static.flickr.com/1246/4728554459_97034bb3a9_z.jpg Sean Foley SCI3050 Science & Civilization Final Project Introduction Two pieces of technology that stand out in the aviation history of World War II are Radar and Bombsights. Both technologies played a crucial role in the defensive and offensive strategies of all the countries involved. During World War II Radio Detecting and Ranging or RADAR, saw its first use in combat operations. (“Early”) Although radar came of age during the war (Goebel) it is often referred to as the weapon that won the war and the invention that changed the world! (“Radar”) Radar was a technology that allowed land bases to detect incoming aircraft and direct their anti-air defenses in the direction of the incoming aircraft.
    [Show full text]
  • NATIONAL HISTORIC LANDMARK NOMINATION CAMP EVANS Page 1 1. NAME of PROPERTY Historic Name
    NATIONAL HISTORIC LANDMARK NOMINATION NPS Form 10-900 USDI/NPS NRHP Registration Form (Rev. 8-86) OMB No. 1024-0018 CAMP EVANS Page 1 United States Department of the Interior, National Park Service National Register of Historic Places Registration Form 1. NAME OF PROPERTY Historic Name: Camp Evans Other Name/Site Number: U.S. Army Signal Corps Laboratory 2. LOCATION Street & Number: Marconi Road and Monmouth Boulevard Not for publication: N/A City/Town: Wall Township Vicinity: N/A State: New Jersey County: Monmouth Code: 025 Zip Code: 07719 3. CLASSIFICATION Ownership of Property Category of Property Private: Building(s): ___ Public-Local: X District: X_ Public-State: __ Site: ___ Public-Federal: X Structure: ___ Object: ___ Number of Resources within Property Contributing Noncontributing 35 13 buildings sites 1 structures objects 35 14 Total Number of Contributing Resources Previously Listed in the National Register: 51 Name of Related Multiple Property Listing: N/A NPS Form 10-900 USDI/NPS NRHP Registration Form (Rev. 8-86) OMB No. 1024-0018 CAMP EVANS Page 2 United States Department of the Interior, National Park Service National Register of Historic Plaaces Registration Form 4. STATE/FEDERAL AGENCY CERTIFICATION As the designated authority under the National Historic Preservation Act of 1966, as amended, I hereby certify that tthis ____ nomination ____ request for determination of eligibility meets the documentation standards for registering properties in the National Register of Historic Places and meets the procedural and professional requirements set forth in 36 CFR Part 60. In my opinion, the property ____ meets ____ does not meet the Natioonal Register Criteria.
    [Show full text]
  • Radar in Meteorology Radar in Meteorology: Battan Memorial And
    RADAR IN METEOROLOGY RADAR IN METEOROLOGY: BATTAN MEMORIAL AND 40TH ANNIVERSARY RADAR METEOROLOGY CONFERENCE EDITED BY DAVID ATLAS American Meteorological Society Boston 1990 © American Meteorological Society 1990 Originally published by American Meteorological Society Boston in 1990 Softcover reprint of the hardcover 1st edition 1990 Permission to use figures, tables, and brief excerpts from this publication in scientific and educational works is hereby granted, provided the source is acknowledged. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. ISBN 978-0-933876-86-6 ISBN 978-1-935704-15-7 (eBook) DOI 10.1007/978-1-935704-15-7 Typeset and printed in the United States of America by Lancaster Press, Lancaster, Pennsylvania. Section openers designed by Helga Hardy. Published by the American Meteorological Society, 45 Beacon Street, Boston, MA 02176. Richard E. Hallgren, Executive Director Kenneth C. Spengler, Executive Director Emeritus Evelyn Mazur, Assistant Executive Director Arlyn S. Powell, Jr., Publications Manager Editorial support provided by Laura Westlund, Pamela Jones, Jon Feld, Linda Esche, Brenda Gray, Harold Nagel, and Susan McClung. Table of Contents Preface . 1x Acknowledgments . x1 Tribute to Professor Louis J. Battan Xlll I. HISTORY 1 Early Developments of Weather Radar during World War II . 3 ].0. Fletcher 2 Weather Radar in the United States Army's Fort Monmouth Laboratories . 7 Donald M. Swingle 3 Radar Meteorology at Radiation Laboratory, MIT, 1941 to 1947 . 16 Isadore Katz and Patrick f.
    [Show full text]
  • INTRODUCTION to RADAR SIGNAL PROCESSING Christos Ilioudis University of Strathclyde
    INTRODUCTION TO RADAR SIG N A L PR O C E S S IN G Christos Ilioudis University of Strathclyde [email protected] Overview ■ History of Radar ■ Basic Principles ■ Principles of Measurements ■ Coherent and Doppler Processing ■ Waveforms Design and Pulse Compression ■ Closing Remarks ■ Reading Material History – Before Radar ■ Between the World Wars, parabolic sound mirrors, were used to provide early warming; ■ Acoustic mirrors had a limited effectiveness, and the increasing speed of aircraft in the 1930s meant WW1 - WW2 that they would already be too close to deal with by the time they had been detected. ■ Radio transmitters had already been in use for over a decade for communications. Top: (L) Bombing during the WW1, (R) “Whisper Dishes” Bottom: (L) WW2 Bombers, (R) Four-horn acoustic locator,1930s History – Radio Detection ■ Radar was first patented and demonstrated in 1904 by the German engineer Christian Hülsmeyer; ■ Watson Watt is generally credited with initiating what would later be called radar; ■ In June 17, 1935, a radio-based detection and ranging was first demonstrated in Great Britain; ■ The first Radar system used by the British comprised 21 stations placed along the country’s eastern coast. Left: (T) Christian Hülsmeyer, (B) Watson Watt, Right: Chain Home coverage map Today – Radar ■ Modern Radar are very diverse; – Military Radars; – Imaging Radars; – Radar Gun; – Automotive Radars; – Civil Aviation Radars; – Weather Radars; – Ground Penetrating Radars; Basic Principles ■ Radar is an acronym for RAdio Detection And Ranging; ■ An object detection system that transmits electromagnetic (EM) waves and analyses the echoes coming from the objects; ■ Why use radar? – Radar can operate in any weather conditions (e.g.
    [Show full text]
  • Coast Artillery Soldiers Using Sound Equipment to Locate Airplanes, C. 1940. Courtesy Gateway NRA/National Park Service
    Coast Artillery Soldiers using sound equipment to locate airplanes, c. 1940. courtesy Gateway NRA/National Park Service Development of Radar on the Jersey Shore | Mary Rasa | www.GardenStateLegacy.com Issue 41 September 2018 Fort Hancock's field station. andy Hook’s strategic location and military importance The four poles were to get a dates back to the Revolutionary War because of its close 100-foot elevation for the Sproximity to the Sandy Hook Channel. This was the only equipment. channel available for large ships entering New York City. British courtesy of the CECOM Historical Office, loyalists were successful in taking over the Sandy Hook Aberdeen Proving Ground, Maryland Lighthouse from the colonists. This allowed the British control of New York Harbor for most of the war. During each subsequent military engagement of the United States, Sandy Hook, and later, Fort Hancock played a role. In 1895, Fort Hancock was established and armed just in time for the Spanish American War. This new fort, was an U.S. Army Coast Artillery Post. The Coast Artillery Corps was charged with maintaining forts at every major harbor in the United States, including New York Harbor. They used rifled cannons, concrete gun emplacements, and underwater mines to protect from enemy attack. In World War I, Fort Hancock once again repeated the role of defender of New York Harbor. In 1907, the new deepwater Ambrose Channel was completed as the main channel into New York. Fort Hancock’s guns needed to cover the range of this Development of Radar on the Jersey Shore | Mary Rasa | www.GardenStateLegacy.com Issue 41 September 2018 View of the radar shelters at channel from the west side.
    [Show full text]
  • A History of Radar Meteorology: People, Technology, and Theory
    A History of Radar Meteorology: People, Technology, and Theory Jeff Duda Overview • Will cover the period from just before World War II through about 1980 – Pre-WWII – WWII – 1940s post-WWII – 1950s – 1960s – 1970s 2 3 Pre-World War II • Concept of using radio waves established starting in the very early 1900s (Tesla) • U.S. Navy (among others) tried using CW radio waves as a “trip beam” to detect presence of ships • First measurements of ionosphere height made in 1924 and 1925 – E. V. Appleton and M. A. F. Barnett of Britain on 11 December 1924 – Merle A. Tuve (Johns Hopkins) and Gregory Breit (Carnegie Inst.) in July 1925 • First that used pulsed energy instead of CW 4 Pre-World War II • Robert Alexander Watson Watt • “Death Ray” against Germans • Assignment given to Arnold F. “Skip” Wilkins: – “Please calculate the amount of radio frequency power which should be radiated to raise the temperature of eight pints of water from 98 °F to 105 °F at a distance of 5 km and a height of 1 km.” – Not feasible with current power production Watson Watt 5 Pre-World War II • Watson Watt and Wilkins pondered whether radio waves could be used merely to detect aircraft • Memo drafted by Watson Watt on February 12, 1935: “Detection of Aircraft by Radio Methods” – Memo earned Watson Watt the title of “the father of radar” – Term “RADAR” officially coined as an acronym by U.S. Navy Lt. Cmdr. Samuel M. Tucker and F. R. Furth in November 1940 • The Daventry experiment – February 26, 1935 – First recorded detection of aircraft by radio waves – Began the full-speed-ahead
    [Show full text]
  • The Cavity Magnetron: Not Just a British Invention
    1. The Cavity Magnetron and Its Historical Corner Practical Signifi cance as a Major Innovation in 1940-1945 he industrial development of the cavity magnetron, and Giuseppe Pelosi Tthe subsequent development of high-power airborne and University of Florence surface microwave radar, appear as a typical case of “major Via di Santa Marta, 3 innovation,” i.e., according to the defi nition often used by I-50139 Florence, Italy technology historians, an invention that leads to practical – and Tel: 055-4796-759; profi table – use serving some recognized need of our society. Fax: 055-4796-767 It has been treated in many books (see, for instance, [1-5]) and E-mail: giuseppe.pelosi@unifi .it, [email protected] in many papers. The most vivid description was probably in [1], a book written by the Welsh physicist, Edward G. Bowen (1911-1991), a prime actor in the develop ment of microwave and airborne radar. Just looking at the titles of these books, it is evident that in many cases the “British (or American) The Cavity Magnetron: pride” of the winners of the Second World War, as well as the trend to exalt history, seems to pre vail over objectiveness and Figure 1. H. A. H. Boot (l) and J. T. Randall in their labo- Not Just a British Invention completeness. Some notable exceptions are from Canadian, ratory after WW II. Boot has in his hands a six-cavity Italian, and French authors, as in [6-8]. They are among the anodic block. very few sources mentioning the decision of the British Air Yves Blanchard1, Gaspare Galati2, and Piet van Genderen3 Ministry to inform – under military secrecy – the dominion governments of the most industrialized Commonwealth nations 1Consulting engineer and historian, retired from Thales (France) (Canada, Australia, South Africa) of the developments in the orders-of-magnitude improvement with respect to their fi rst E-mail: [email protected] fi eld of radar, pushing ahead the development of radar in those prototype!).
    [Show full text]