Digital Wireless Basics: Mobile Phone History Page One
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TelecomWriting.com: Digital Wireless Basics: Mobile Phone History Page One TelecomWriting.com Home Advanced search E-mail me! Cell phones and plans Mobile Telephone History ---- Pages: (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) Levine's GSM/PCS .pdf file (11) (Packet switching) Telephone history series (Next topic: Standards) Mobile telephone history Introduction Telephone manual Digital wireless and cellular roots go back to the 1940s when Digital wireless basics commercial mobile telephony began. Compared with the furious pace of development today, it may seem odd that Cellular telephone basics mobile wireless hasn't progressed further in the last 60 years. Where are our video watch phones? There were many reasons for this delay but the most important ones were technology, Seattle Telephone Museum cautiousness, and federal regulation. Telecom clip art collection As the loading coil and vacuum tube made possible the early telephone network, the wireless revolution began only after Bits and bytes low cost microprocessors and digital switching became Packets and switching available. The Bell System, producers of the finest landline telephone system in the world, moved hesitatingly and at times with disinterest toward wireless. Anything AT&T produced had to work reliably with the rest of Cell phone materials their network and it had to make economic sense, something not possible for them I-Mode Page with the few customers permitted by the limited frequencies available at the time. Land mobile Frequency availability was in turn controlled by the Federal Communications Commission, whose regulations and unresponsiveness constituted the most significant factors hindering radio-telephone development, especially with cellular Bluetooth radio, delaying that technology in America by perhaps 10 years. Cell phones on airplanes In Europe and Japan, though, where governments could regulate their state run Cellular reception problems telephone companies less, mobile wireless came no sooner, and in most cases later Cell phones and plans than the United States. Japanese manufacturers, although not first with a working cellular radio, did equip some of the first car mounted mobile telephone services, their technology equal to whatever America was producing. Their products enabled several first commercial cellular telephone systems, starting in Bahrain, Digital Wireless Basics: Tokyo, Osaka, Mexico City. Introduction Wireless and Radio Defined Wireless History Communicating wirelessly does not require radio. Everyone's noticed how Standards appliances like power saws cause havoc to A.M. radio reception. By turning a saw on and off you can communicate wirelessly over short distances using Morse http://www.privateline.com/PCS/history.htm (1 of 6) [11/13/2001 2:44:42 PM] TelecomWriting.com: Digital Wireless Basics: Mobile Phone History Page One Basic Radio Principles code, with the radio as a receiver. But causing electrical interference does not constitute a radio transmission. Inductive and conductive schemes, which we will Cellular defined look at shortly, also communicate wirelessly but are limited in range, often Frequency reuse difficult to implement, and do not fufill the need to reliably and predictably communicate over long distances. So let's see what radio is and then go over what Cell splitting it is not. Cellular and PCS frequencies Weik defines radio as: Transmitting digital signals "1. A method of communicating over a distance by modulating Introducing wireless systems electromagnetic waves by means of an intelligence bearing-signal and radiating these modulated waves by means of transmitter and a The network elements receiver. 2. A device or pertaining to a device, that transmits or receives electromagnetic waves in the frequency bands that are The main wireless categories between 10kHz and 3000 GHz." Basic digital principles Interestingly, the United States Federal Communications Commission does not Modulation define radio but the U.S. General Services Administration defines the term simply: Turning speech into digital 1. Telecommunication by modulation and radiation of electromagnetic waves. 2. A transmitter, receiver, or transceiver used Frames, slots and channels for communication via electromagnetic waves. 3. A general term IS-54: D or Digital AMPS applied to the use of radio waves. IS-136: TDMA based cellular http://fts.gsa.gov/library/glossary/glossary_r.htm Call processing Radio thus requires a modulated signal within the radio spectrum, using a transmitter and a receiver. Modulation is a two part process, a current called the Appendix carrier, and a signal bearing information. We generate a continuous, high Wireless' systems chart frequency carrier wave, and then we modulate or vary that current with the signal we wish to send. Notice how a voice signal varies the carrier wave below: Cellular and PCS frequencies chart Mobile Phone History Table of Contents: Introduction Wireless and Radio defined 1820 --> Pre-history This technique to modulate the carrier is called amplitude modulation. Amplitude 1842: Wireless by Conduction means strength. A.M. means a carrier wave is modulated in proportion to the strength of a signal. The carrier rises and falls instantaneously with each high and 1843 --> Early Electromagnetic low of the conversation.The voice current, in other words, produces an immediate Research and equivalent change in the carrier. Wireless by Induction For voice this is exactly the same way a telephone works, using the essential 1865: Induction and Dr. Loomis principle of variable resistance. A voice in telephony modulates the current of a telephone line. Compared to a telephone line, the unmodulated carrier in radio is Early Radio Discoveries simply the steady and continuous current the transmitter generates. When you talk 1879: D.E. Hughes and the first the radio puts, superimposes, or impresses your conversation's signal on the radio-telephone reception current the radio is transmitting. Conversation causes the current's resistance to go up and down, that is, your voice varies or modulates the carrier. I illustrate this http://www.privateline.com/PCS/history.htm (2 of 6) [11/13/2001 2:44:42 PM] TelecomWriting.com: Digital Wireless Basics: Mobile Phone History Page One 1880: The Photophone and the idea with the diagram below. The only difference between a telephone and radio is first voice radio-telephone call that we call the transmitter a microphone. Now that we've quickly looked at radio, let's go on to its early development. 1880 to 1900: Radio development begins in earnest 1910: The first car-telephone 1924: The first car mounted radio-telephone 1937 --> Early conventional radio-telephone development The Modern Era Begins 1946: The first commercial American radio-telephone service 1947: Cellular systems first discussed 1948: The first automatic Pre-History radiotelephone service As we can tell already, and as with the telephone, a radio is an electrical 1969: The first cellular radio instrument. A thorough understanding of electricity was necessary before system inventors could produce a reliable, practical radio system. That understanding didn't happen quickly. Starting with the work of Oersted in 1820 and continuing 1973: The Father of the Cell until and beyond Marconi's successful radio system of 1897, dozens of inventors Phone? and scientists around the world worked on different parts of the radio puzzle. In an 1978: First generation analog era of poor communication and non-systematic research, people duplicated the cellular systems begin work of others, misunderstood the results of other inventors, and often misinterpreted the results they themselves had achieved. While puzzling over the Discussion: Growth of Japanese mysteries of radio, many inventors worked concurrently on power generation, cellular development telegraphs, lighting, and, later, telephones. We should start at the beginning. 1981: NMT -- The first In 1820 Danish physicist Christian Oersted discovered electromagnetism, the multinational cellular system critical idea needed to develop electrical power and to communicate. In a famous Table of Analog or First experiment at his University of Copenhagen classroom, Oersted pushed a compass Generation Cellular Systems under a live electric wire. This caused its needle to turn from pointing north, as if acted on by a larger magnet. Oersted discovered that an electric current creates a 1982 --> The Rise of GSM magnetic field. But could a magnetic field create electricity? If so, a new source of 1990: North America goes power beckoned. And the principle of electromagnetism, if fully understood and digital: IS-54 applied, promised a new era of communication . In 1821 Michael Faraday reversed Oersted's experiment and in so Principles of Modern doing discovered induction. He got a weak current to flow in a wire Communications Technology revolving around a permanent magnet. In other words, a magnetic (external link to Amazon) (Artech field caused or induced an electric current to flow in a nearby wire. House) Professor A. Michael In so doing, Faraday had built the world's first electric generator. Noll Mechanical energy could now be converted to electrical energy. Is that clear? This is a very important point. The simple act of moving This .pdf file is from Noll's ones' hand caused current to flow. Mechanical energy into book described above: it is a electrical energy. But current was produced only when the short, clear introduction to magnetic field was in motion, that is, when it was changing.