WHERE THERE IS NO TELEPHONE Chapter 1. HOW RADIO WAVES TRAVEL Topics: 1.1 Basic theory of short-wave radio 1.1.1 Frequency and Time 1.1.2 Distance 1.1.3 Sunspot Cycle 1.2 Propagation Predictions 1.2.1 Computer Prediction 1.2.2 Calculation by hand 1.2.3 Experience and Experiment 1.2.4 Rule of Thumb 1.2.5 Unpredicted effects Return to Table of Contents 1.1 Basic theory of short-wave radio. Short-wave bands are to be found on many broadcast radio receivers. There are various broadcast bands and to tune into them you are given the wavelength,for example 25, 31 or 41 metres. In radio communications the tuning information is given in kHz (kiloHertz) or MHz (MegaHertz), formerly Kc/s or Mc/s. Radio waves travel at the speed of light i.e. 300,000 km per second and because wavelength and frequency are related you can easily translate from wavelength to frequency by the relationship: 300 Frequency in MHz = __________________ Wavelength in metres.
WHERE THERE IS NO TELEPHONE Chapter 2. AERIALS Topics: 2.1 Standing Wave Ratio 2.2 Dipole Aerials 2.2.1 Dimensions 2.2.2 Constuction 2.2.3 Horizontal directivity 2.2.4 Height 2.3 Inverted Vee Aerial 2.4 Vertical Aerial 2.4.1 Earthing of vertical aerials 2.4.2 Directivity 2.5 Mobile Aerials 2.6 Multi-frequency aerials 2.6.1 Multi-dipoles 2.6.2 Broadband aerials 2.6.3 Long wire aerials and Aerial Tuning Units 2.6.4 Single Dipole for Two Frequencies Return to Table of Contents The purpose of an aerial is to launch the power from a radio transmitter into space in the form of radio waves. These waves then proceed, either by reflection from the ionosphere or along the surface of the earth, to the receiving location. Here the waves are captured by another aerial and steered to the receiver. So the aerial is a very important part of your radio system and it is essential that you use an aerial which is suitable for the particular frequency you intend to transmit. You may be told that all you require is a long piece of wire,the longer the better. Whilst such a wire could be suitable for reception an additional unit would be necessary to tune the wire before it was suitable for transmission. .
WHERE THERE IS NO TELEPHONE Chapter 3.TRANSCEIVERS AND POWER SUPPLIES Topics: 3.1 Transceivers 3.1.1 Transmitter power output 3.1.2 Transceiver power requirements 3.1.3 Transceiver controls 3.2 Power Supplies 3.2.1 Mains supplies 220.127.116.11 Constant voltage transformers 18.104.22.168 Fail to battery 3.2.2 Generators 3.2.3 Batteries 22.214.171.124 Types 126.96.36.199 Capacity 188.8.131.52 Life expectancy 184.108.40.206 Charging 220.127.116.11 Discharging 18.104.22.168 Low Voltage Disconnect 22.214.171.124 New Battery from Old 3.2.4 Solar Battery Chargers 126.96.36.199 Available Solar Energy 188.8.131.52 Electrical Connection 3.2.5 Diodes in Solar Chargers 184.108.40.206 What is a diode? 220.127.116.11 Main diode 18.104.22.168 Blocking diode 22.214.171.124 By-pass diodes 126.96.36.199 Diodes for multiple loads .
WHERE THERE IS NO TELEPHONE Chapter 4. HOW TO PLAN YOUR RADIO NETWORK Topics: 4.1 Who do you want to talk to? 4.2 Licences 4.2.1 Applying for a licence 4.2.2 Licence Fee 4.2.3 Frequency choice 4.2.4 Limitations 4.2.5 Import Licence 4.3 What type of radio communications? 4.3.1 Citizen Band 4.3.2 VHF 4.3.3 Amateur Radio Return to Table of Contents When it is decided that your group needs some form of communication and could benefit from a radio communication network you should consider what this implies in some detail. Before you get down to choosing a transceiver from the glossy brochures there are some general aspects to be considered. What are the facilities you would like and what facilities you can actually afford to buy, licence, operate and maintain? What form of radio communication between which places will the Government of the country permit? You may plan several different systems on paper before you arrive at the one which is acceptable in all its aspects. Keep all your various plans because you could find that after going through various planning and costing stages and through government departments etc. you need to go back to an earlier plan! 4.1. Who do you want to talk to? The first stage of your planning should be to take a good look at the present method of communication .
WHERE THERE IS NO TELEPHONE Chapter 5. COSTS AND CHOICES Topics: 5.1 Costs 5.1.1 Capital Costs 5.1.2 Shipping 5.1.3 Customs Duty 5.1.4 Installation 5.1.5 Operating 5.1.6 Maintenance 5.2 Choice of equipment 5.2.1 Transceivers 188.8.131.52 Supply Voltage 184.108.40.206 Ease of maintenance and modification 220.127.116.11 Ease of use 18.104.22.168 Future availability 22.214.171.124 Protection 126.96.36.199 Channel Frequencies 188.8.131.52 Microphone 184.108.40.206 Power Requirements 5.2.2 Aerials 5.2.3 Power Sources 5.2.4 Test Equipment 5.2.5 Modifications 220.127.116.11 Reverse polarity protection 18.104.22.168 Microphone switches 22.214.171.124 Earphone socket 126.96.36.199 Squelch 188.8.131.52 Power light .
WHERE THERE IS NO TELEPHONE Chapter 6. HOW TO INSTALL A RADIO SYSTEM Topics: 6.1 Where to put the equipment 6.1.1 The Radio Room 184.108.40.206 Radio Desk 220.127.116.11 Power supply 6.2 Installation 6.2.1 Transceiver 18.104.22.168 Cooling 22.214.171.124 Microphone clip 6.2.2 Power Supplies 126.96.36.199 Connections 188.8.131.52 Colour Coding 184.108.40.206 Plugs and sockets 220.127.116.11 Solar Panel 18.104.22.168 Battery 22.214.171.124 Fail to battery 6.2.3 Protection against lightening 126.96.36.199 Arrestors 188.8.131.52 Aerials 184.108.40.206 Transceiver 220.127.116.11 Static 6.2.4 Aerials 18.104.22.168 Aerial Supports 22.214.171.124 Aerial adjustment 126.96.36.199 Erection 188.8.131.52 In the Radio Room 184.108.40.206 Fitting a plug to a coaxial cable .
WHERE THERE IS NO TELEPHONE Chapter 7. HOW TO OPERATE A RADIO NETWORK Topics: 7.1 Choice of Operator 7.1.1 A Good Operator 7.1.2 Control or HQ Station 7.1.3 Outlying stations 7.1.4 Stand-by operators 7.1.5 Training an operator 7.2 Operating the Equipment 7.2.1 Transceiver Controls 220.127.116.11 Clarifier 18.104.22.168 Squelch 22.214.171.124 RF Gain 126.96.36.199 Interference 188.8.131.52 USB/LSB 184.108.40.206 Earphones 220.127.116.11 Transmit 7.2.2 Care of Equipment 18.104.22.168 Controls 22.214.171.124 Microphones 126.96.36.199 Cables and Aerials 188.8.131.52 Battery 184.108.40.206 Lightening Danger 220.127.116.11 Aerial Tuning Units 18.104.22.168 Check List 7.2.3 Fault Finding 22.214.171.124 Transmitting and receiving difficulties 126.96.36.199 Battery voltage problems.
WHERE THERE IS NO TELEPHONE Chapter 8. HOW TO MAINTAIN A RADIO NETWORK Topics: 8.1 Staff 8.2 Cost and Payment 8.3 Spare Parts 8.3.1 Fuses 8.4 Tools 8.4.1 Basic Tools 8.4.2 Workshop Tools 8.5 Routine Maintenence 8.6 Fault Finding 8.6.1 False Indications 188.8.131.52 Power Light 184.108.40.206 Transmit Light 8.6.2 Do It Yourself 220.127.116.11 Trial and Error 18.104.22.168 Diagnostic Aids 22.214.171.124 Testing Diodes 8.7 Workshop Repair 8.7.1 Requirements 8.7.2 Instructions 8.8 Contract Maintenence Return to Table of Contents There are several aspects of a radio network which have to be satisfied if it is to give a continuous satisfactory service. These aspects are dealt with in each chapter, the importance of each has been .
WHERE THERE IS NO TELEPHONE Chapter 9. ADDITIONAL FACILITIES Topics: 9.1 Selective Calling 9.2 Modems 9.3 Facsimile 9.4 Electrocardiographs 9.5 Morse Code 9.6 Linear Amplifier 9.7 Aerial Tuning Units 9.8 Remote Controlled Coaxial Switch 9.9 Telephone Handset 9.10 Boom Microphone Return to Table of Contents In addition to the basic facility of transmitting and receiving speech a radio network of HF SSB transceivers can be used as the medium for transferring other forms of information. These can include teletyped messages which are typed out on a teleprinter by the operator for transmission and which are received and printed out automatically. Computers can be linked by radio and enabled to "talk to each other" and pictures can be sent over radio links. All these facilities are usually provided by additional "add on" equipment which simply plugs in to the basic transceiver. Note that SSB transmitter power rating is in watts pep, the equivalent continuous power output will be less than half that figure. So when continuous tones are being transmitted e.g. using a modem, the transmitter output must be kept within the specified limit. 9.1. Selective Calling Selective calling systems in various forms have been in use on radio networks for many years. The facility provided can be likened to that of a telephone in as much as you are able to cause a bell or buzzer .
WHERE THERE IS NO TELEPHONE Chapter 10. Packet Radio Topics: 10.1 HF,VHF and UHF Links 10.2 Satellite Links Return to Table of Contents Packet radio is a form of data communication which has several forms e.g. X25 is in professional use, AX25 is used by amateurs and there are other formats. The text message to be transmitted is broken up into packets which may contain up to 256 characters. AX25 packets take the following form: They start and end with synchronising signal thus making the data within the packet a synchronous format.