The DISH® Network: an Operator’S Manual
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The DISH® Network: An Operator’s Manual A detailed guide to how DISH programming gets from provider to customer, written for both technical and non‐technical readers. Edward B. Tomme Technical or not Your background matters little Your knowledge will grow. Huge program content Is compressed and encrypted So more can be sent. Our satellites sit In fixed spots quite far away Transceiving signals. Whispers from the sky Grow strong and are directed Deep inside a house. Complex yet friendly Boxes find, unlock, and send Channels to the screen. Preface When I joined DISH in late 2012 part of my job was to become the technical subject matter expert on everything DISH does. As I began my studies, I immediately looked for a document that could guide me to the understanding I needed. I quickly discovered there wasn’t one. Everything I found was either dispersed across the Net (both Inter‐ and Intra‐), was contained within the corporate memory of select individuals, or hadn’t really been looked at in depth by DISH as it was the purview of other companies such as EchoStar. I even asked where our company technical library was and discovered one did not exist. I began collecting documents and books to help get me up to speed, but these were still islands of information that were being pumped into my personal corporate knowledge, helping me but not necessarily others. I realized that while my particular job required me to be aware of the gamut of DISH technical operations, there were bound to be others who could benefit from at least parts of this hard‐gained knowledge. With that thought in mind, I decided to write this guide to move the understanding of the DISH technical process from perishable, piecemeal, individualized knowledge to a systematic, accessible reference for everyone from engineers to corporate leaders. I’ve used the word “technical” several times already, and my background is as a physicist. However, before you decide this document will be over your head, please take a few minutes to look at the beginnings of each chapter. I taught undergraduate physics at the United States Air Force Academy and was recognized in student end‐of‐course critiques as having an unusual talent for making highly technical concepts accessible to intelligent non‐specialists. Leveraging that talent, I’ve designed this document with a diverse audience in mind. The first parts of each chapter are overviews of the basic concepts required to understand the process, but without a lot of technical jargon. Collectively, these overviews should give a sufficient understanding of what we do at DISH for those of you who aren’t normally technically inclined. The remainder of each chapter will treat the topic in much more depth, a level at which technical specialists will likely need to know. I hope you find this information useful, and welcome your feedback on ways to improve it. ‐‐ Ed Tomme, Englewood, Colorado, June, 2013 i ii The DISH Network: An Operator’s Manual Table of Contents Preface ................................................................................................ i Table of Contents .............................................................................. iii List of Abbreviations, Acronyms, and Symbols ....................................ix List of Figures ................................................................................... xiii SI Prefixes ......................................................................................... xxi Overview ............................................................................................ 1 How This Document Is Organized ........................................................................ 1 Math the Easy Way .............................................................................................. 2 A Short Course on Signal Flow from Provider to Customer ................................. 3 Chapter Summary ................................................................................................ 5 1. Prepping the Signal ......................................................................... 7 The Basics ............................................................................................................. 7 Content Acquisition. ..................................................................................... 7 MPEG. ........................................................................................................... 8 Encryption. ................................................................................................... 9 Multiplexing. .............................................................................................. 10 Summary. ................................................................................................... 10 Technical Discussion........................................................................................... 11 Content Acquisition Methods ........................................................................ 11 What is MPEG? .............................................................................................. 13 YCbCr Down‐Sampling. ............................................................................... 14 MPEG Basics. .............................................................................................. 17 Run‐Length Compression. .......................................................................... 19 Moving Object Recognition. ....................................................................... 20 Warping. ..................................................................................................... 22 The MPEG Coding Process. ......................................................................... 22 Audio Compression. ................................................................................... 27 The Business Case for MPEG Encoders and Decoders ............................... 29 iii MPEG‐4 vs. MPEG‐2. .................................................................................. 30 Encryption ..................................................................................................... 31 Data Transport—Combining Multiple Programs on a Single Channel ........... 35 Chapter Summary .......................................................................................... 38 2. The Uplink Center ......................................................................... 39 The Basics ........................................................................................................... 39 Electromagnetic Waves. ............................................................................. 40 Antenna Physics. ........................................................................................ 42 Bandwidth and Signal Coding. .................................................................... 43 Technical Discussion........................................................................................... 47 The Electromagnetic Spectrum ...................................................................... 48 Waves. ........................................................................................................ 49 The Electromagnetic Spectrum and the Atmosphere. ............................... 50 Political Considerations. ............................................................................. 56 Antennas and Diffraction ............................................................................... 58 Wavefronts. ................................................................................................ 59 Reflection. .................................................................................................. 60 Diffraction. ................................................................................................. 62 Beamwidth and Gain. ................................................................................. 65 Phase Shift Keying .......................................................................................... 69 Pulse Code Modulation. ............................................................................. 69 Phase Shift Modulation. ............................................................................. 72 Data Bandwidth ............................................................................................. 79 Spectral Bandwidth ........................................................................................ 81 Radio Versus Visible ....................................................................................... 87 Polarization .................................................................................................... 90 Chapter Summary .......................................................................................... 96 3. DISH Satellites .............................................................................. 97 The Basics ........................................................................................................... 97 Satellite Orbits. ........................................................................................... 98 Satellite Communications. ....................................................................... 100 Technical Discussion......................................................................................... 103 A Primer on Satellite Orbits.......................................................................... 103 Gravity. ....................................................................................................