A Short History of Radio
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Toward a Large Bandwidth Photonic Correlator for Infrared Heterodyne Interferometry a first Laboratory Proof of Concept
A&A 639, A53 (2020) Astronomy https://doi.org/10.1051/0004-6361/201937368 & c G. Bourdarot et al. 2020 Astrophysics Toward a large bandwidth photonic correlator for infrared heterodyne interferometry A first laboratory proof of concept G. Bourdarot1,2, H. Guillet de Chatellus2, and J-P. Berger1 1 Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France e-mail: [email protected] 2 Univ. Grenoble Alpes, CNRS, LIPHY, 38000 Grenoble, France Received 19 December 2019 / Accepted 17 May 2020 ABSTRACT Context. Infrared heterodyne interferometry has been proposed as a practical alternative for recombining a large number of telescopes over kilometric baselines in the mid-infrared. However, the current limited correlation capacities impose strong restrictions on the sen- sitivity of this appealing technique. Aims. In this paper, we propose to address the problem of transport and correlation of wide-bandwidth signals over kilometric dis- tances by introducing photonic processing in infrared heterodyne interferometry. Methods. We describe the architecture of a photonic double-sideband correlator for two telescopes, along with the experimental demonstration of this concept on a proof-of-principle test bed. Results. We demonstrate the a posteriori correlation of two infrared signals previously generated on a two-telescope simulator in a double-sideband photonic correlator. A degradation of the signal-to-noise ratio of 13%, equivalent to a noise factor NF = 1:15, is obtained through the correlator, and the temporal coherence properties of our input signals are retrieved from these measurements. Conclusions. Our results demonstrate that photonic processing can be used to correlate heterodyne signals with a potentially large increase of detection bandwidth. -
Cell Phone Use on the Roads in 2002 December 2004 6
U.S. Department of Transportation National Highway Traffic Safety Administration DOT HS 809 580 December 2004 Technical Report Cell Phone Use on the Roads in 2002 Published By: National Center for Statistics and Analysis This document is available to the public from the National Technical Information Service, Springfield, VA 22161 Technical Report Documentation Page 2. Government Accession No. 3. Recipient's Catalog No. 1. Report No. DOT HS 809 580 4. Title and Subtitle 5. Report Date Cell Phone Use on the Roads in 2002 December 2004 6. Performing Organization Code NPO-101 7. Author(s) 8. Performing Organization Report No. Glassbrenner, Donna, Ph.D. 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Mathematical Analysis Division, National Center for Statistics and Analysis National Highway Traffic Safety Administration 11. Contract or Grant No. U.S. Department of Transportation DTNH22-00-07001 NPO-101, 400 Seventh Street, S.W. Washington, D.C. 20590 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Mathematical Analysis Division, National Center for Statistics and Analysis NHTSA Technical Report National Highway Traffic Safety Administration U.S. Department of Transportation 14. Sponsoring Agency Code NPO-101, 400 Seventh Street, S.W. Washington, D.C. 20590 15. Supplementary Notes Data collection, estimation, and variance estimation for NHTSA’s National Occupant Protection Use Survey were conducted by Westat, Inc under the direction of NHTSA’s National Center for Statistics and Analysis under federal contract number DTNH22-00-07001. Also we thank Mike Goodman and Julie Barker in NHTSA’s Office of Advanced Safety Research, and Paul Tremont in the Office of Research and Technology for helpful comments. -
Army Radio Communication in the Great War Keith R Thrower, OBE
Army radio communication in the Great War Keith R Thrower, OBE Introduction Prior to the outbreak of WW1 in August 1914 many of the techniques to be used in later years for radio communications had already been invented, although most were still at an early stage of practical application. Radio transmitters at that time were predominantly using spark discharge from a high voltage induction coil, which created a series of damped oscillations in an associated tuned circuit at the rate of the spark discharge. The transmitted signal was noisy and rich in harmonics and spread widely over the radio spectrum. The ideal transmission was a continuous wave (CW) and there were three methods for producing this: 1. From an HF alternator, the practical design of which was made by the US General Electric engineer Ernst Alexanderson, initially based on a specification by Reginald Fessenden. These alternators were primarily intended for high-power, long-wave transmission and not suitable for use on the battlefield. 2. Arc generator, the practical form of which was invented by Valdemar Poulsen in 1902. Again the transmitters were high power and not suitable for battlefield use. 3. Valve oscillator, which was invented by the German engineer, Alexander Meissner, and patented in April 1913. Several important circuits using valves had been produced by 1914. These include: (a) the heterodyne, an oscillator circuit used to mix with an incoming continuous wave signal and beat it down to an audible note; (b) the detector, to extract the audio signal from the high frequency carrier; (c) the amplifier, both for the incoming high frequency signal and the detected audio or the beat signal from the heterodyne receiver; (d) regenerative feedback from the output of the detector or RF amplifier to its input, which had the effect of sharpening the tuning and increasing the amplification. -
How to Configure Radios for Use with Repeaters
Concept of How to Configure Your Handheld and Mobile Radio for Use on a Repeater System VA6RPL Peter LaGrandeur Calgary Amateur Radio Association 2015 Learning Conference Limitations of “Standalone” Radios such as Handhelds and Vehicle Mounted Mobiles. Short Range of Coverage Signal easily blocked by major obstacles such as mountains, valleys, urban infrastructure What is a “Repeater” Radio? A repeater is basically a two way radio that receives a signal on one frequency, and simultaneously retransmits it on another frequency. It can retransmit with much greater power than received, and can send over a much wider area. A good example is where users are scattered in various areas separated by mountains; if a repeater is situated on top of a central mountain, it can gather signals from surrounding valleys, and rebroadcast them to all surrounding valleys. Handy! From there, repeater stations can be “linked” together to connect a series of repeater radios, each in a different area. With this, every time a user transmits on his mobile or handheld, his call will be heard simultaneously over all the repeater transmitters. And, yes! Repeater stations can now be connected via the internet. This internet linking is called IRLP – Internet Relay Linking Project. For example, a repeater in Calgary can link, via the internet, with an IRLP repeater anywhere in the world. You can carry on a two way radio conversation with someone in a faraway land with the assistance of the internet. Locating of Repeater Stations The higher the better. Yes, there are even satellite repeaters for amateur radio. In places that afford the best coverage in as many directions as possible. -
A Brief History of Radio Broadcasting in Africa
A Brief History of Radio Broadcasting in Africa Radio is by far the dominant and most important mass medium in Africa. Its flexibility, low cost, and oral character meet Africa's situation very well. Yet radio is less developed in Africa than it is anywhere else. There are relatively few radio stations in each of Africa's 53 nations and fewer radio sets per head of population than anywhere else in the world. Radio remains the top medium in terms of the number of people that it reaches. Even though television has shown considerable growth (especially in the 1990s) and despite a widespread liberalization of the press over the same period, radio still outstrips both television and the press in reaching most people on the continent. The main exceptions to this ate in the far south, in South Africa, where television and the press are both very strong, and in the Arab north, where television is now the dominant medium. South of the Sahara and north of the Limpopo River, radio remains dominant at the start of the 21St century. The internet is developing fast, mainly in urban areas, but its growth is slowed considerably by the very low level of development of telephone systems. There is much variation between African countries in access to and use of radio. The weekly reach of radio ranges from about 50 percent of adults in the poorer countries to virtually everyone in the more developed ones. But even in some poor countries the reach of radio can be very high. In Tanzania, for example, nearly nine out of ten adults listen to radio in an average week. -
Mass Media in the USA»
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by BSU Digital Library Mass Media In The USA K. Khomtsova, V. Zavatskaya The topic of the research is «Mass media in the USA». It is topical because mass media of the United States are world-known and a lot of people use American mass media, especially internet resources. The subject matter is peculiarities of different types of mass media in the USA. The aim of the survey is to study the types of mass media that are popular in the USA nowadays. To achieve the aim the authors fulfill the following tasks: 1. to define the main types of mass media in the USA; 2. to analyze the popularity of different kinds of mass media in the USA; 3. to mark out the peculiarities of American mass media. The mass media are diversified media technologies that are intended to reach a large audience by mass communication. There are several types of mass media: the broadcast media such as radio, recorded music, film and tel- evision; the print media include newspapers, books and magazines; the out- door media comprise billboards, signs or placards; the digital media include both Internet and mobile mass communication. [4]. In the USA the main types of mass media today are: newspapers; magazines; radio; television; Internet. NEWSPAPERS The history of American newspapers goes back to the 17th century with the publication of the first colonial newspapers. It was James Franklin, Benjamin Franklin’s older brother, who first made a news sheet. -
History of Radio Broadcasting in Montana
University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 1963 History of radio broadcasting in Montana Ron P. Richards The University of Montana Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation Richards, Ron P., "History of radio broadcasting in Montana" (1963). Graduate Student Theses, Dissertations, & Professional Papers. 5869. https://scholarworks.umt.edu/etd/5869 This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. THE HISTORY OF RADIO BROADCASTING IN MONTANA ty RON P. RICHARDS B. A. in Journalism Montana State University, 1959 Presented in partial fulfillment of the requirements for the degree of Master of Arts in Journalism MONTANA STATE UNIVERSITY 1963 Approved by: Chairman, Board of Examiners Dean, Graduate School Date Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number; EP36670 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMT Oiuartation PVUithing UMI EP36670 Published by ProQuest LLC (2013). -
The Evolution of U.S. Spectrum Values Over Time
The Evolution of U.S. Spectrum Values Over Time Michelle Connolly, Department of Economics, Duke University Nelson Sa, Department of Economics, Brandeis University Azeem Zaman, Department of Statistics, Harvard University Chris Roark, Department of Economics, University of Chicago Akshaya Trivedi, Trinity College, Duke University, Class of 2018 Working Paper Series 2018 | 121 Evolution of spectrum values 1 The Evolution of U.S. Spectrum Values Over Time Michelle Connolly1, Nelson Sá2, Azeem Zaman3, Chris Roark4, and Akshaya Trivedi5 February 13, 2018 Abstract We consider 1997 to 2015 data from FCC spectrum auctions related to cellular services to attempt to identify intrinsic spectrum values. Relative to previous literature, we control for license specific auction rules, and introduce measures to separate out technological progress that effectively reduces spectrum scarcity from progress that increases demand. Results confirm that technological changes have led to increases in the relative value of higher frequencies. Surprisingly, 47 percent of these licenses have been won by “small” bidders, representing 27 percent of the real value of these licenses. The use of bidding credits further appears to consistently reduce auction competition. Keywords: Spectrum, Spectrum Scarcity, Auctions, FCC, Auction Rules, Mobile Applications, Spectral Efficiency, Broadband Speeds, Closed Auctions, Small Bidders, “The Google Effect” JEL Codes: L5, O3, K2 1 Corresponding author: Michelle Connolly, [email protected], 213 Social Sciences, Box 90097, Department of Economics, Duke University, Durham, NC 27708. 2 Department of Economics, Brandeis University. 3 Department of Statistics, Harvard University. 4 Department of Economics, University of Chicago. 5 Trinity College, Duke University Class of 2018. We gratefully acknowledge the support of NSF grant 1314468. -
The Power of Light
David N Payne Dedicated to: Guglielmo Marconi and Charles Kao Director ORC University of Southampton 1909 2009 Nobel Laureates in Physics Wireless and optical fibres The power of light GPS systems, synchronous data networks, cell phone telephony, time stamping financial trades Large scale interferometers for telescopes Optical gyroscopes Data centres/computer interconnects Financial traders You can’t beat vacuum for loss, speed of light or stability! The Very Large Telescope Interferometer (VLTI) on Paranal Mountain Data Centre Interconnection Information flow/unit area and latency is key in supercomputers and data centres 20,000 km of fibre per data centre in Facebook alone! Vacuum transit time is 30% lower High-performance: applications in inertial guidance, navigation, platform stabilization, GPS flywheeling, etc. Lower-performance: Consumer / industrial applications in Performancemotion control, industrial limited processing, byconsumer glass electronics, core etc. Periodic lattice of holes Hollow air core Advantage: Typically less than 0.1% optical power in cladding. Ultra-low nonlinearity, lower loss? Vacuum fibre technology Fibres that largely ignore the materials from which they are made Power in glass < 0.01% low nonlinearity Transmission loss < 0.01 dB/m As you wouldLow Latencyexpect (30% from lower) vacuum! Phase insensitive Radiation hard IR transmitting The new anti-resonant fibre 22.3 µm 40.2 µm Width = 359.6 nm 20μm OFC 2016, Los Angeles, PDPTh5A.3 Low Latency data communications • Data transmission at 99.7% the speed of light in vacuum • ‘Only’ 69.4% in a conventional fibre Latency savings (vs conventional fibres): 1m 1.54 ns 100m 154 ns 1km 1.54 µs 100km 154 µs Phase Insensitive Fibres The phase of a signal in a fibre changes with temperature owing to: • Change in refractive index • Change in fibre length • Vacuum fibre temperature sensitivity 2 ps/km/K • 18.5 times smaller than conventional fibres Dr Radan Slavik Slavik et al., Scientific Reports 2015. -
The FCC Filing
Dr. Theodore S. Rappaport, PE PO BOX 888 Riner, Virginia 24149 [email protected] November 10, 2018 Commissioners Federal Communications Commission 445 12th Street, SW Washington, DC 20554 Dear FCC Commissioners: This is a notice of ex parte, based on email communication I had with the CTO of the FCC, Dr. Eric Burger, on November 8, 2018, his reply on November 10, 2018, and my reply on November 11, 2018. The email communication is centered around a posting that appeared on the FCC ECFS system on November 7, 2018, and is part of an ongoing proceeding at the FCC, NPRM 16-239, that I and thousands of others view as a direct threat to the national security interests of the United States, as well as being detrimental to the hobby of amateur (“ham”) radio. Public comments made in FCC’s NPRM 16-239, and in FCC proceedings RM-11708, RM-11759, and RM-11306 proposed by the American Radio Relay League, show the vast number of rule violations and national security threats that continue to go unaddressed by the FCC. Commenters such as me view the lack of FCC acknowledgement of these problems as jeopardizing the safety of US citizens. NPRM 16-239 attempts to remove a limit on the baud rate of High Frequency (HF) shortwave transmissions, without first addressing ongoing rule violations pertaining to proper usage of the amateur radio service, the use of obscured, private messaging which is forbidden in Part 97 rules and creates national security concerns, as well as other violations. If allowed, NPRM 16-239 would perpetuate the current violations, and would authorize obscured transmissions of unlimited bandwidth over the global airwaves, further increasing the danger to our national security, since these transmissions cannot be intercepted or eavesdropped by other amateur radio operators or the FCC. -
A Survey on Mobile Wireless Networks Nirmal Lourdh Rayan, Chaitanya Krishna
International Journal of Scientific & Engineering Research, Volume 5, Issue 1, January-2014 685 ISSN 2229-5518 A Survey on Mobile Wireless Networks Nirmal Lourdh Rayan, Chaitanya Krishna Abstract— Wireless communication is a transfer of data without using wired environment. The distance may be short (Television) or long (radio transmission). The term wireless will be used by cellular telephones, PDA’s etc. In this paper we will concentrate on the evolution of various generations of wireless network. Index Terms— Wireless, Radio Transmission, Mobile Network, Generations, Communication. —————————— —————————— 1 INTRODUCTION (TECHNOLOGY) er frequency of about 160MHz and up as it is transmitted be- tween radio antennas. The technique used for this is FDMA. In IRELESS telephone started with what you might call W terms of overall connection quality, 1G has low capacity, poor 0G if you can remember back that far. Just after the World War voice links, unreliable handoff, and no security since voice 2 mobile telephone service became available. In those days, calls were played back in radio antennas, making these calls you had a mobile operator to set up the calls and there were persuadable to unwanted monitoring by 3rd parties. First Gen- only a Few channels were available. 0G refers to radio tele- eration did maintain a few benefits over second generation. In phones that some had in cars before the advent of mobiles. comparison to 1G's AS (analog signals), 2G’s DS (digital sig- Mobile radio telephone systems preceded modern cellular nals) are very Similar on proximity and location. If a second mobile telephone technology. So they were the foregoer of the generation handset made a call far away from a cell tower, the first generation of cellular telephones, these systems are called DS (digital signal) may not be strong enough to reach the tow- 0G (zero generation) itself, and other basic ancillary data such er. -
The Case of GEC/Marconi
The Effect of Corporate Restructuring on the Shareholders’ Value: The Case of GEC/Marconi Magdy Abdel-Kader1* and Vagia Mentzeniot2 1 Brunel Business School. Brunel University. Uxbridge. Middlesex UB8 3PH. UK * Corresponding author: Tel: +44 (0)1895 266739. Fax: +44 (0)1895 269775. Email: [email protected] 2 Finance Division, Piraeus Bank Group, Headquarters, Stadiou & Amerikis 4, Athens, 10557, Greece Abstract GEC/Marconi’s transformation from a diversified conglomerate to a focused telecommunications and information technology company was an eventful and rambling transmission that resulted in the deterioration of shareholders’ value. It represents one of the most dramatic falls from grace in British corporate history and one of the greatest corporate governance fiascos of all time. The study investigates the wealth effects of Marconi’s sell-offs and acquisitions on its shareholders’ value by calculating the abnormal returns on the announcement days of all the disposals/acquisition during 1996-2002. The results support the view that shareholders’ value increases when a company proceeds to corporate sell-offs to pursue a focus strategy. However, the authors conjecture that GEC/Marconi has destroyed shareholders’ value through these disposals/acquisitions because of several mistakes, such as being prone to heavy debt. © 2007 World Research Organization. All rights reserved Keywords: Marconi, GEC, Restructuring, Disposals, Acquisitions, Divestiture Citation: Abdel-Kader, M. & Metzeniot, V. (2007). The effect of corporate restructuring on the stakeholder’s value: the case of GEC/Marconi. World Journal of Business Management. 1(1) 28-46 Introduction acquired firms rather than acquiring firms. A study by Berger and Ofek (1995) showed that diversification Diversification in the 1950’s and 1960’s gave rise to destroys value.