Tracking Systems for Satellite Communications
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Regulation of Digital Communications
Full-fibre broadband for all Steve Unger A major strategic shift will encourage the roll-out of new Virgin Media is putting its money where its mouth is and ‘fibre to the premise’ networks to homes and businesses laying fibre to the premise Ofcom, DCR, Feb 2016 Tom Mockridge, Virgin Media, April 2016 We want to go further, faster – and have set an ambitious Through the Fibre First programme, Openreach is getting target for 15 million premises to be connected to full on with the job of building an Ultrafast Britain fibre by 2025, with nationwide coverage by 2033. Clive Selley, Openreach, Feb 2018 Jeremy Wright, DCMS SoS, FTIR, July 2018 As a deadline, that is laughably unambitious. If we want British Broadband will oversee a publicly-owned full- to unite our country and our society, we should commit fibre network and deliver free broadband to every now to delivering full fibre to every home in the land not home, with a phased roll-out over ten years. To do that in the mid 2030s – but in five years at the outside. we will bring the relevant parts of BT, including Openreach, into public ownership Boris Johnson, June 2019 Jeremy Corbyn, Nov 2019 Why do we have poor availability of full fibre today? What’s currently being done to address this? Is a more radical approach feasible and desirable ? We’ve been able to deploy full fibre for 30 years “BT’s vision of the future UK telecommunications infrastructure comprises an all-fibre, all-digital, highly integrated broadband network” T R Rowbotham, BT Research Labs, 1989 (Source: Plans for a British -
Microwave Performance Characterization of Large Space Antennas
JPL PUBLICATION 77-21 N77-24333 PERFOPMANCE (NASA-CR-153206) MICROWAVE OF LARGE SPACE ANTNNAS CHARACTEPIZATION p HC A05/MF A01 Propulsion Lab.) 79 (Jet CSCL 20N Unclas G3/32 29228 Performance Microwave Space Characterization of Large Antennas Ep~tOUCED BY NATIONAL TECHNICAL SERVICE INFORMATION ER May 15, T977 . %TT OFCOMM CE ,,,.ESp.Sp , U1IELD, VA. 22161 National Aeronautics and Space Administration Jet Propulsion Laboratory Callfornia Institute of Technology Pasadena, California 91103 TECHNICAL REPORT STANDARD TITLE PAGE -1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. JPL Pub. 77-21 _______________ 4. Title and Subtitle 5. Report Date MICROWAVE PERFORMANCE CHARACTERIZATION OF May 15, 1977 LARGE SPACE ANTENNAS 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. D. A. Bathker 9. Performing Organization Name and Address 10. Work Unit No. JET PROPULSION LABORATORY California Institute of Technology 11. Contract or Grant No. 4800 Oak Grove Drive NAS 7-100 Pasadena, California 91103 13. Type of Report and Period Covered 12. Sponsoring Agency Name and Address JPL Publication NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 14. Sponsoring Agency Code Washington, D.C. 20546 15. Supplementary Notes 16. Abstract The purpose of this report is to place in perspective various broad classes of microwave antenna types and to discuss key functional and qualitative limitations. The goal is to assist the user and program manager groups in matching applications with anticipated performance capabilities of large microwave space antenna con figurations with apertures generally from 100 wavelengths upwards. The microwave spectrum of interest is taken from 500 MHz to perhaps 1000 GHz. -
PARABOLIC DISH ANTENNAS Paul Wade N1BWT © 1994,1998
Chapter 4 PARABOLIC DISH ANTENNAS Paul Wade N1BWT © 1994,1998 Introduction Parabolic dish antennas can provide extremely high gains at microwave frequencies. A 2- foot dish at 10 GHz can provide more than 30 dB of gain. The gain is only limited by the size of the parabolic reflector; a number of hams have dishes larger than 20 feet, and occasionally a much larger commercial dish is made available for amateur operation, like the 150-foot one at the Algonquin Radio Observatory in Ontario, used by VE3ONT for the 1993 EME Contest. These high gains are only achievable if the antennas are properly implemented, and dishes have more critical dimensions than horns and lenses. I will try to explain the fundamentals using pictures and graphics as an aid to understanding the critical areas and how to deal with them. In addition, a computer program, HDL_ANT is available for the difficult calculations and details, and to draw templates for small dishes in order to check the accuracy of the parabolic surface. Background In September 1993, I finished my 10 GHz transverter at 2 PM on the Saturday of the VHF QSO Party. After a quick checkout, I drove up Mt. Wachusett and worked four grids using a small horn antenna. However, for the 10 GHz Contest the following weekend, I wanted to have a better antenna ready. Several moderate-sized parabolic dish reflectors were available in my garage, but lacked feeds and support structures. I had thought this would be no problem, since lots of people, both amateur and commercial, use dish antennas. -
Towards 5G – an Operators Perspective Evolution Or Revolution?
Towards 5G – an operators perspective Evolution or Revolution? Paul Crane Head of Practice Mobile, Wireless & Network Services BT Research & Innovation WiMob Oct 2015 WiMob 2015 Towards 5G – an operators perspective Evolution or Revolution? Contents BT Research and Innovation 5G – Needs and Expectations Capacity technical challenges IoT technical challenges Low latency technical challenges New Services Conclusions WiMob 2015 BT has a long history of ‘purposeful innovation’ 3 With many world first achievements World Firsts 1846: Telecommunications company: Electric Telegraph Company 1926: Two way transatlantic telephone conversation by radio 1943: Programmable computer: Colossus 1962: Telephone call via satellite 1968: Digital exchange 1980: Purpose-designed optical fibre submarine cable 1984: 140 Mbit/s commercial single mode optical fibre link 1989: Satellite telephone system: Skyphone 1999: GPRS live data call over a mobile network 2013: World’s first G.fast trial 2014: 3 Tb/s optical fibre link in the core network © British Telecommunications plc WiMob 2015 4 Adastral Park – ‘a key UK engineering centre’ © British Telecommunications plc WiMob 2015 5 Using the power of communications to make a better world Purpose Assist living Always best connected Innovation Ultra-Hi-Definition The Internet of Things Entertainment Science Engineering © British Telecommunications plc WiMob 2015 Tomorrows citizens WiMob 2015 Cellular Data Growth Cellular Data in Western Europe (TB) 3,000,000 2,500,000 2,000,000 1,500,000 1,000,000 500,000 0 2014 2015 -
Sky’S Response to Ofcom’S Strategic Review of Digital Communications – Discussion Document
SKY’S RESPONSE TO OFCOM’S STRATEGIC REVIEW OF DIGITAL COMMUNICATIONS – DISCUSSION DOCUMENT Executive Summary 1. Sky welcomes Ofcom’s strategic review. It provides an opportunity to address a series of important issues that have implications not only for consumers of communications services in the UK, but also for the long term health of the UK economy. 2. It is critical that Ofcom approaches the review with vision, imagination and an open mind. The purpose of this strategic review should not be to confirm the merits of the status quo, or to search for potential minor adjustments in course. Ofcom should be prepared to consider options that have the potential to deliver significantly better outcomes in the communications sector over the next decade and beyond. 3. The review is an excellent opportunity to take a step back from ‘business as usual’, to consider what is working well in the sector, and what isn’t. It also provides an opportunity to consider critical questions in relation to the UK’s communications infrastructure – questions that risk falling between the gaps in Ofcom’s regular cycle of market reviews. 4. It is now apparent that there is substantial concern with a series of growing problems in the sector, shared by a wide range of communications providers (“CPs), consumers, and politicians. These include: (i) the increasing dominance of high speed broadband services by BT, which risks unwinding the benefits of years of strong competition in broadband services; (ii) the inadequate quality of service delivered by Openreach – and its significant impact, every day, on large numbers of UK consumers and businesses, and (iii) the level and type of investment in the UK’s fixed line communications infrastructure. -
BT Research & Innovation
BT Research & Innovation You used to only know us for our phones and broadband. Now you know us for BT Sport TV too. At BT you will find us innovating new creations every day. For example… Did you know… We enabled 450 million people around the world to keep up with London 2012, and provided the largest ever high-density public wi-fi in the world Did you know… In May 2013 we achieved a world record data transmission speed of 800Gbit/s equivalent to that of sending seven HD DVDs in a single second Did you know… We’ve registered over 600 patents in the last five years and invested £560million in research and development in 2012 alone Did you know… we are hiring? Summer Internship Opportunities… We are offering summer internship opportunities for undergraduates within BT Research & Innovation (R&I) during the Summer vacation of 2014. R&I is a unit within the BT Technology, Service & Operations unit (TSO), providing central research for the BT Group through researching & prototyping solutions of potential relevance to BT’s future. We work with customers, universities, vendors, and, most importantly, BT’s market facing units to take good technical ideas and turn them into great reality. That could start with things like intellectual property, prototypes, and trial systems but hopefully ends up with new products, processes or systems to help BT serve its customers around the world. R&I’s scope includes – for example - the futures of the home and wireless. It covers the evolution of our high-speed core and access networks. -
W6IFE Newsletter March 2011 Edition President John Oppen KJ6HZ 4705 Ninth St Riverside, CA 92501951-288-1207 [email protected]
W6IFE Newsletter March 2011 Edition President John Oppen KJ6HZ 4705 Ninth St Riverside, CA 92501951-288-1207 [email protected]. Vice President Doug Millar, K6JEY 2791 Cedar Ave Long Beach, CA 90806 562-424-3737 [email protected] Recording Sec Larry Johnston K6HLH 16611 E Valeport Lancaster CA 93535 661-264-3126 [email protected] Corresponding Sec Jeff Fort Kn6VR 10245 White Road Phelan CA 92371 909-994-2232 [email protected] Treasurer Dick Bremer, WB6DNX 1664 Holly St Brea CA 92621 714-529-2800 [email protected] Editor Bill Burns, WA6QYR 247 Rebel Rd Ridgecrest, CA 93555 760-375-8566 [email protected] Webmaster Dave Glawson, WA6CGR 1644 N. Wilmington Blvd Wilmington, CA 90744 310-977-0916 [email protected] ARRL Interface Frank Kelly, WB6CWN PO Box 1246, Thousand Oaks, CA 91358 805 558-6199 [email protected] W6IFE License Trustee Ed Munn, W6OYJ 6255 Radcliffe Dr. San Diego, CA 92122 858-453-4563 [email protected]. At the March 3, 2011 SBMS meeting we will have Doug, K6JEY talking to us about power meters. His talk will have two parts. The first part will be a review of the theory of how power meter couplers, terminated meters, and calorimeters work and what their general calibration limits are. The second part of the presentation will be to calibrate member's 23cm and 13cm watt meters using a high power calorimeter from Doug's lab (A Bird 6091). We hope to have 10-200 watts available on 23cm and a smaller amount for 13cm. We may also have a set up for 2m as well for general calibration. -
Admission Document Prepared in Accordance with the AIM Rules
233582 Gold Cover Spread 8mm Spine 07/10/2014 14:06 Page 1 Placing and Admission to AIM Gamma Communications plc Nominated AdviserAdviser,, Broker & Sole Bookrunner Perivan Financial Print 233582 233582 Gold pp001-pp004 07/10/2014 14:06 Page 1 THIS DOCUMENT IS IMPORTANT AND REQUIRES YOUR IMMEDIATE ATTENTION If you are in any doubt as to the contents of this document or as to what action you should take you should consult your stockbroker, bank manager, solicitor, accountant or other independent financial adviser authorised under the Financial Services and Markets Act 2000 (“FSMA”) who specialises in advising on the acquisition of shares and other securities. This document comprises an admission document prepared in accordance with the AIM Rules. Application will be made for the Ordinary Shares to be admitted to trading on AIM. It is expected that Admission will become effective and that trading in the Ordinary Shares on AIM will commence at 8.00 a.m. on 10 October 2014. The Ordinary Shares are not dealt on any other recognised investment exchange and it is emphasised that no application has been, or is being, made for the Ordinary Shares to be admitted to any such exchange. This document is not an approved prospectus for the purposes of section 85 of FSMA, has not been prepared in accordance with the Prospectus Rules published by the Financial Conduct Authority (“FCA”) and a copy of it has not been, and will not be, delivered to the UK Listing Authority in accordance with the Prospectus Rules or delivered to or approved by any other authority which could be a competent authority for the purposes of the Prospectus Directive. -
The New IT Crowd the Role of the IT Director in Simplifying Complexity
The New IT Crowd The role of the IT director in simplifying complexity THE PERSPECTIVE SERIES New insights into the UK workplace In partnership with Vodafone UK Foreword In times of change, we’ve seen again and again that those who sit back and don’t react, risk being left behind. This means we’re all constantly having to evolve and adapt the way we do business. It’s exciting, but also challenging. What’s fuelling this change? As we’ve explored in previous reports in the Perspective series, the answer is lots of things; not least the rapid consumerisation of technology. It has changed the way that enterprise and people work. To meet these challenges head on, successful businesses are looking to redefine Jeroen Hoencamp, the role of the IT director. Skill sets are changing and expectations are rising, so it’s CEO, Vodafone UK no surprise we are seeing senior IT directors shifting from a reactionary role to a front seat in the development of overall business strategy. At Vodafone, we’ve responded to this shift by developing award-winning teams of digital, technology and innovation specialists. But top teams need leadership and so the greatest change has been in the new multi-dimensional role of the CIO and CTO. We are witnessing a new breed of leaders, who are surrounded by digital natives and have to continually develop and enhance their knowledge and skill sets. These leaders are driven by an understanding of strategic business needs they are a more innovative, entrepreneurial species than their predecessors. The job description used to be technologist first, technical people manager second and business manager, if at all, last. -
Communications Satellites
I. I IPAGESJ i < INASA CR OR fmx OR AD NUMBER) COMMUNICATIONS SATELLITES A CONTINUING BIBLIOGRAPHY Hard copy (HC) Microfiche (MF) NATIONAL AERONAUTICS AND SPACE ADMINISTRATION .J I I, i This bibliography was prepared by the Scientific and Technical Information Facility operated for the National Aeronautics and Space Administration by Documentation Incorporated ~ ~~~ NASA SP-7004 (01) COMMUNICATIONS SATELLITES A CONTINUING BIBLIOGRAPHY A selection of annotated references to unclas- sified reports and journal articles that were introduced into the NASA Information System during the period May 1964-January 1965. Scientific and Technical In formotion Division NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D.C. APRIL 1965 This document is available from the Clearinghouse for Federal Scientific and Technical Information (OTS), Springfield, Virginia, 22 1 5 1 , for $1 .OO INTRODUCTION With the publication of this first supplement, NASA SP-7004 (Ol), to the Continuing Bibliography on “Communications Satellites” (SP-7004), the National Aeronautics and Space Administration continues its program of distributing selected references to reports and articles on aerospace topics that are currently under intensive study. The references are assembled in this form to provide a convenient source of information for use by scientists and engineers who need this kind of specialized compilation. Continuing Bibliographies are updated periodically by supplements which can be appended to the original issue. All references included in SP-7004 (01) have been announced in either Scientific and Technical Aerospace Reports (STAR)or International Aerospace Abstracts (IAA) and were introduced into the NASA information system during the period May, 1964-January, 1965. The transmission of information by means of communications satellites is a new tech- nique that promises to be a powerful stimulus for effective international cooperation in the investigation of space. -
BT Group Plc Annual Report 2020 BT Group Plc Annual Report 2020 Strategic Report 1
BT Group plc Group BT Annual Report 2020 Beyond Limits BT Group plc Annual Report 2020 BT Group plc Annual Report 2020 Strategic report 1 New BT Halo. ... of new products and services Contents Combining the We launched BT Halo, We’re best of 4G, 5G our best ever converged Strategic report connectivity package. and fibre. ... of flexible TV A message from our Chairman 2 A message from our Chief Executive 4 packages About BT 6 investing Our range of new flexible TV Executive Committee 8 packages aims to disrupt the Customers and markets 10 UK’s pay TV market and keep Regulatory update 12 pace with the rising tide of in the streamers. Our business model 14 Our strategy 16 Strategic progress 18 ... of next generation Our stakeholders 24 future... fibre broadband Culture and colleagues 30 We expect to invest around Introducing the Colleague Board 32 £12bn to connect 20m Section 172 statement 34 premises by mid-to-late-20s Non-financial information statement 35 if the conditions are right. Digital impact and sustainability 36 Our key performance indicators 40 Our performance as a sustainable and responsible business 42 ... of our Group performance 43 A letter from the Chair of Openreach 51 best-in-class How we manage risk 52 network ... to keep us all Our principal risks and uncertainties 53 5G makes a measurable connected Viability statement 64 difference to everyday During the pandemic, experiences and opens we’re helping those who up even more exciting need us the most. Corporate governance report 65 new experiences. Financial statements 117 .. -
The Cassegrain Antenna
The Cassegrain Antenna Principle of a Cassegrain telescope: a convex secondary reflector is located at a concave primary reflector. Figure 1: Principle of a Cassegrain telescope Sieur Guillaume Cassegrain was a French sculptor who invented a form of reflecting telescope. A Cassegrain telescope consists of primary and secondary reflecting mirrors. In a traditional reflecting telescope, light is reflected from the primary mirror up to the eye-piece and out the side the telescope body. In a Cassegrain telescope, there is a hole in the primary mirror. Light enters through the aperture to the primary mirror and is reflected back up to the secondary mirror. The viewer then peers through the hole in the primary reflecting mirror to see the image. A Cassegray antenna used in a fire-control radar. Figure 2: A Cassegray antenna used in a fire-control radar. In telecommunication and radar use, a Cassegrain antenna is an antenna in which the feed radiator is mounted at or near the surface of a concave main reflector and is aimed at a convex subreflector. Both reflectors have a common focal point. Energy from the feed unit (a feed horn mostly) illuminates the secondary reflector, which reflects it back to the main reflector, which then forms the desired forward beam. Advantages Disadvantage: The subreflectors of a Cassegrain type antenna are fixed by bars. These bars The feed radiator is more easily and the secondary reflector constitute supported and the antenna is an obstruction for the rays coming geometrically compact from the primary reflector in the most effective direction. It provides minimum losses as the receiver can be mounted directly near the horn.