Poole Basic Radio

Principles and Technology
1. Auflage 1998
ISBN: 978-0-08-093846-2
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 224 Seiten

Basic Radio is a wide ranging introduction to the principles of radio waves, transmission and reception, and to the technologies of broadcasting, satellite and personal communications. As well as being a textbook for vocational courses such as City & Guilds and BTEC Ian Poole's book is essential reading for all communications and broadcast professionals.Radio technology is becoming increasingly important in today's highly sophisticated electronics industry. There are traditional uses including broadcasting and point to point communications, as well as new technologies associated with cellular phones and wire-less data links. All of these developments mean that there will be a greater need for radio engineers at all levels.Ian Poole is an electronic engineer currently involved in project management for the development of a large radio system. He is a regular contributor to Electronic - The Maplin Magazine, Everyday Practical Electronics and Practical Wireless. He has also written several books on amateur radio. - An accessible introduction to radio engineering - Suitable for FE students, technicians and hobbyists - Covers the latest technologies: cellular phones, wire-less data links

Ian Poole is an established electronics engineering consultant with considerable experience in the communications and cellular markets. He is the author of a number books on radio and electronics and he has contributed to many magazines in the UK and worldwide. He is also winner of the inaugural Bill Orr Award for technical writing from the ARRL.

Autoren/Hrsg.

Poole, Ian

Inhaltsverzeichnis

1;Front Cover
;1
2;Basic Radio: Principles and Technology;4
3;Copyright Page ;5
4;Table of Contents;6
5;Chapter 1. Radio today, yesterday and tomorrow;8
5.1;The story of radio;11
5.2;Radio tomorrow;21
6;Chapter 2. Radio waves andpropagation;22
6.1;Radio waves;22
6.2;Frequency to wavelength conversion;24
6.3;Polorlzction;25
6.4;Radio spectrum;25
6.5;How radio signals travel;27
6.6;Levers above the earth;27
6.7;Ground wave;31
6.8;Skywaves;32
6.9;Distances and the angle of radiation;35
6.10;Multiple reflections;36
6.11;Chordal hop
;37
6.12;Critical frequency;38
6.13;MUF;38
6.14;LUF;39
6.15;Skip zone;39
6.16;Stelte of the ionosphere;39
6.17;Propagation prediction;42
6.18;VHF and above;43
6.19;Tropo-scatter;44
6.20;Sporadic E;45
6.21;Meteor scatter;46
6.22;Frequencies above 3 GHz;48
7;Chapter 3. Ccpccltors, inductorsand filters;49
7.1;Capacitors;49
7.2;Inductors;54
7.3;Tuned circuits;56
7.4;Mutuel inductance and transformers;57
7.5;Q factor;59
7.6;Low pass and high pass filters;62
7.7;Band-pass filters;64
7.8;LC filters;67
7.9;Quartz crystals;68
7.10;Crystal filters;71
7.11;Monollthlc crystal filters;73
7.12;Mechanical filters;74
7.13;Ceramic filters;75
7.14;Frequency standards;75
8;Chapter 4. Modulation;77
8.1;Radio carrier;77
8.2;Morse;78
8.3;Amplitude modulation;80
8.4;Single sideband;84
8.5;Prequency modulation;85
8.6;Frequency shift keying;89
8.7;Phase modulation;94
8.8;Phase shift keying;96
8.9;Pulse modulation;96
8.10;Frequency hopping;100
8.11;Sprecd spectrum;101
8.12;Transmission codes;101
9;Chapter 5. Receivers;104
9.1;Crystal set;105
9.2;TRF receiver;106
9.3;Direct conversion receiver;108
9.4;The superhet;111
9.5;Basic superhet receiver;114
9.6;Overcoming image response problems;120
9.7;IF breakthrough;122
9.8;Spurious signals;122
9.9;Autornotlc gain control;123
9.10;Multiple conversion sets;125
9.11;Synthesizers;128
9.12;Multi-loop synthesizers;133
9.13;Diirect digital synthesizers;135
9.14;Phose noise and reciprocal mixing;137
9.15;Filters;138
9.16;Selectivity and filters;139
9.17;Demodulator;139
9.18;Digital signal processing;148
9.19;Sensitivity and noise;150
9.20;Signal to noise ratio;151
9.21;SINAD;153
9.22;Noise factor and noise figure;154
9.23;Strong signal and overload;155
9.24;Intermodulation distortion;156
9.25;Third order intercept;157
9.26;Blocking;158
9.27;Cross-modulation;158
9.28;Dynamic range;158
10;Chapter 6. Transmitters;160
10.1;Transmitter building blocks;160
10.2;Amplifiers;162
10.3;Mixers;167
10.4;Filters and matching networks;168
10.5;Simple Morse transmitter;168
10.6;Amplitude modulation transmitter;170
10.7;Sirlgle sideband transmitter;173
10.8;Frequency modulation transmitter;176
10.9;Speech processing;179
11;Chapter 7. Antenna systems;185
11.1;Resonance and bandwidth;185
11.2;Impedance;187
11.3;Gain and directivity;187
11.4;Arlgle of radiation;189
11.5;Height;190
11.6;Antenna system;190
11.7;Feeder;190
11.8;Feeder impedance;191
11.9;Standing waves;191
11.10;Loss;195
11.11;Velocity factor;196
11.12;Types of feeder;196
11.13;Matching unit;202
11.14;Types of antenna;202
12;Chapter 8. Broadcasting;217
12.1;AM broadcasts;217
12.2;VIHF FM;221
12.3;Stereo;221
12.4;C-QUAM;225
12.5;RDS;230
12.6;Di!gital audio broadcasting;235
13;Chapter 9. Satellites;241
13.1;Satellite orbits;241
13.2;Satellites;244
13.3;Placing a satellite in orbit;246
13.4;Path calculations;247
13.5;Comrrumlcotlons satellites;247
13.6;Navigational satellites;250
13.7;Oither uses;251
14;Chapter 10. Personal communications;253
14.1;Basic system;253
14.2;Base stations;256
14.3;Mobile phones;256
14.4;System control and call routeing;258
14.5;Control and signals;259
14.6;Digital systems;260
14.7;Private mobile radio (PMR) systems;261
15;Appendix: Basic calculations;263
16;Index;266

Leseproben

1

Radio today, yesterday and tomorrow

The benefits of radio technology are an integral part of our everyday life. Over the past decades we have come to accept radio, taking it for granted and not realizing how much it contributes to the running of modern society.

Radio performs many functions today, but the most obvious must be domestic broadcasting. Most homes have a variety of radio sets, ranging from the relatively simple and cheap portable radios, through the more sophisticated car radios to the high fidelity systems. All of these sets offer a high degree of performance which is the result of use and development over many years. Even so, the performance of radio sets is being improved and new facilities are being introduced all the time. The introduction of wide-band FM represented a major improvement when it was first introduced in the early 1950s. Stereo and RDS (Radio Data System) are two more which are in use today, and digital audio broadcasting has started. This brings true CD quality to radio broadcasts as well as allowing data to be broadcast at the same time.

Cellular phones are another benefit which have been brought about by the development of radio. They have enabled people to make phone calls or to be contacted even when they are away from home or the office. Their flexibility has meant that since their introduction in the UK in 1984 there has been a phenomenal growth in this market. Phones are available very cheaply, and even the line rental and call charges are falling as the number of operators increases. This means that a wide variety of people are able to use these phones. Initially they were mainly for business use. Now with the falling charges the number of private users is increasing.

The introduction of the cellular phone systems has done much to advance radio technology. Since their first introduction the sizes of phones have fallen. The first portable sets required the use of large batteries, whereas now the phones are truly hand-held and can be slipped into any pocket. Achieving this has required a large amount of development. More areas of the phones have been integrated onto silicon chips. Now low power consumption, ultra high frequency, radio frequency integrated circuits are commonplace where a few years ago they were few and far between.

Figure 1.1 A modern ‘World Band’ radio Courtesy of Sony UK Ltd

Figure 1.2 A pocket sized cellular phone Courtesy of Sony UK Ltd

Wireless communications have also enabled information to be sent to and from all parts of the world more quickly. Now it is possible to send and receive data, faxes, or voice from almost anywhere in the world very easily. A good example of the way information can be sent more swiftly is shown in the way news is received from around the world almost instantaneously. This can be seen by comparing the news reports of the Second World War, and the Gulf War of 1991. In the 1940s it took several hours for recorded reports from the front-line correspondents to reach the broadcasting stations. Film reports took several days or weeks before they were seen as newsreels in the local cinemas. Now with satellite communications, modern video techniques and television, things happen much faster. In the Gulf War the action was seen by millions in their homes as it happened. Fortunately there are many more less hostile examples of how radio has helped improve the standards of modern life. Here radio has enabled many people to be rescued by the emergency services far more efficiently than if there were no radio present.

There has been a vast amount of investment needed to achieve the high standards of communication needed today. Satellites, microwave links, cellular phone base stations, sophisticated radio data links are but a few which are needed to support today’s requirements. To achieve this a number of different types of technology are needed: antennas, transmitters, and receivers as well as several other items are all needed to make up the complete system. This provides a great amount of variety for anyone looking to take up radio as a career or hobby.

Before progressing into today’s radio technology it is interesting to put it in perspective and look at the way in which radio developed. Over more than a hundred years, many people have helped it reach its current state of development. The story of its development is fascinating and can be traced back to people like Volta, Ampere and Ohm who made some of the first discoveries associated with electricity; but the story of radio itself begins with a brilliant Scot named Maxwell.

The story of radio

Maxwell was born in 1831 and entered Edinburgh University when he was only sixteen. After graduating, he spent time at a number of universities, but it was when he was at King’s College in London that he undertook most of the work into electromagnetic theory for which he is famous. He published three main papers between 1855 and 1864, and finally summarized his work in a book entitled Treatise on Electricity and Magnetism. His work proved the existence of an electromagnetic wave. However, much of Maxwell’s work was theoretical and he was never able to demonstrate the presence of electromagnetic waves in practice. Sadly, Maxwell died at the early age of 48, and the work he started was left to others to continue.

The quest for the electromagnetic wave took many years. A number of people, including Edison and Henry, came close to discovering it. However, it was a German named Heinrich Hertz to whom the honour fell.

Hertz performed a wide variety of experiments to prove the existence of these new waves. He also gave a number of demonstrations and lectures. In one of these he used an induction coil connected to a loop of wire in which two large spheres were placed slightly apart. The induction coil generated a large voltage in the circuit causing a spark to jump across the gap. In turn this caused a spark to jump across the gap of a similar coil with two spheres placed within a few metres of the transmitter.

Using other equipment Hertz managed to prove many of the basic properties of these waves. He showed that they had the same velocity as light, and they were refracted and reflected in the same way. As Hertz had discovered the waves, they soon became known as Hertzian waves.

With the existence of the electromagnetic wave firmly established it did not take long before people started to think of using them for communicating. However, to be able to achieve this it was necessary to be able to have a much better way of detecting them. This came in the form of the coherer. It was initially designed by a Frenchman named Edouard Branly in 1890. He discovered that the resistance of a glass tube filled with metal filings fell from a very high resistance to a few hundred ohms when the filings cohered or clung together when an electrical discharge took place nearby. It could then be reset quite easily by a small tap on the glass.

After its initial discovery the coherer was greatly improved and popularized by an English scientist named Sir Oliver Preece. Such were his improvements that in 1894 he was able to detect signals from a transmitter a few hundred yards away.

It was around this time that a young Italian named Marconi started to experiment with Hertzian waves. His drive, intuition and business sense enabled this new science to progress much faster than it would otherwise have done.

Marconi was born in Bologna in Northern Italy in 1874, receiving a private education during his early years. Despite his parents’ expectations he failed to gain a place at Bologna University. Fortunately he had a growing interest in science and he was encouraged by a family friend who was a lecturer at the university. Marconi was allowed to sit through his lectures and consequently he discovered about the new Hertzian waves.

Marconi quickly became interested and soon started to perform many experiments in the attic of his parents’ house. Early in the summer of 1895 he managed to transmit a signal a distance of a few yards. By the end of the summer he had succeeded in receiving a signal over 2 kilometres away from the transmitter.

Even at this early stage Marconi was able to see the commercial possibilities. Accordingly he approached the Italian Ministry of Posts with his ideas for wireless communications, but his proposal was turned down. It was this rejection which caused Marconi to come to England in 1896.

On his arrival he soon set to work and filed a patent for a system of Wireless Telegraphy using Hertzian waves which was granted on 2 June 1896. In England there was considerably more interest for Marconi’s work. Soon he was introduced to a man named William Preece who was the chief engineer of the Post Office.

Marconi gave some preliminary demonstrations of his equipment in the laboratory and then he set up a transmitter and receiver on the roofs of some buildings in London a few hundred yards apart. The success of this demonstration promoted a further demonstration on Salisbury Plain in September 1896 when representatives of the Post Office together with others from the War Office and the Navy were present.

The Navy saw the possibilities of using wireless equipment for communication at sea and they showed considerable interest. However, Marconi also started to sell his equipment to other maritime users. Initially the take-up was slow, but soon other organizations such as Lloyd’s endorsed its use as a method of sending distress signals and very quickly more vessels were fitted with...