What is amateur radio?

Amateur radio involves the use of radio waves to communicate and make friends with other amateurs around the World who happen to be on the air and within range.

Unlike a mobile phone you do not need to know the number or the person in order to make contact, and unlike the Internet there is a universal shorthand that can be used to communicate basic greetings and information independent of the local languages. Also unlike both the mobile phone and the Internet, there is nothing to pay after the initial outlay.

Communication can be made by voice, text, or with pictures. It brings together basic physics, electronics, computing, photography, and radio etiquette.

The communication range can be increased in a number of ways e.g.

However the satellites are too low to be in stationary orbit and only appear above the horizon for 5 to 20 minutes at a time. Also, the characteristics of the ionised layers above the Earth are very changeable depending on the frequency in use, the time of day, the season and the sunspot cycle. Skill is therefore required to make the best use of the prevailing conditions - you can never be sure which countries you can reach and who you can make contact with at any particular time. This is the continuing challenge of radio, and explains why there are so many modes of transmission in use and in development.

More information can be found on the 'TX factor' web site which contains a series of professionally produced high definition videos created by radio amateurs. They explore the history of amateur radio, rigs, antennas, operating modes, propagation, sport radio, training, club news, RSGB news, world news - in fact covering all aspects of the amateur radio hobby. These free to view programmes are compatible with phones, computers, tablets and smart TVs. Click on the highlighted address to visit the site - http://www.txfilms.co.uk/txfactor/

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Is it like CB?

It is a little bit, the best thing about the Citizens Band, and the main reason it was introduced as an alternative to amateur radio, is that the CB user needs little or no technical knowledge or expertise in order to successfully operate CB.

The UK Citizens Band can be used for work and play and is ideal where two or more people wish to keep in touch within a 6 to 12 km range. The conversations are free and it is possible to talk to numerous people in a group at the same time. It is a useful resource if you are involved in activities such as caravanning and camping clubs, off road driving, boating and fishing, or simply want to keep in touch with a group of friends or acquaintances.

There are 80 channels to choose from lying between 26.965 and 27.99125 MHz laid out in two blocks of 40. The upper frequency block was legalised in 1981 and the lower frequency block was added in 2006 (CEPT/EU channels) to harmonies with the European frequencies. The transmission mode is FM (narrow band frequency modulation) with AM (amplitude modulation) and SSB (single side band modulation) being allowed in the CEPT channels since 27/6/2014. The permitted powers are 4Watts FM, 4Watts AM and 12Watts SSB.

Unfortunately the CB frequencies require a relatively long antenna and tend to propagate poorly indoors and hence are mainly installed in vehicles. Many users of hand held radios have therefore moved to the PMR446 band.

PMR446 transceivers

The UK PMR446 radios provide 8 channels spanning the frequencies from 446.000 to 446.100 MHz and are also licence free. The much higher frequency allows the antennas to be reduced in size for hand held use. The radiated power is limited to 0.5 watts which gives a range of approx 1.5 km under average operating conditions.

Short range transceivers

General purpose UK short range radio devices use the frequencies between 49.82 to 49.98 MHz and are also licence exempt. They are limited to a radiated power of 0.01 Watts and are used by toy walkie-talkies, baby monitors, garage doors etc. Typical outdoor range is 50m.

Marine VHF bands

In contrast the marine band VHF (156-174 MHz) used by sea going craft and inland waterways in the UK are international standards. They require a marine radio operators VHF certificate of competence in order to get licensed. The radios can be used by boats at sea to contact the Coast Guards up to 50km away, or between yachts on the sea 10 to 15km away. More details can be obtained from the Royal Yachting Association (RYA).

Amateur bands

Amateur radio on the other hand, whilst restricting your contacts to thousands of other amateurs for non-commercial purposes, makes communication possible over large distances as well as short opening up the whole world for free once you are licensed. It is also used on yachts that occasionally go to sea as the equipment is much cheaper than the marine specific rigs. There are a number of nets on the air for the purpose of allowing sailors to report their positions and itinerary, receive weather updates, or to call for assistance.

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Modes

A number of different 'modes' co-exist to enable radio amateur transmissions to carry the required information because each has its own advantages and disadvantages. The most common types in use are summarised below:-

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Digital Signals

The digital modes have become very popular with amateurs because of the availability of lots of free software to run on PCs with sound cards. There are regions of the spectrum reserved for the digital modes. Most software includes a waterfall display to help tuning and identification. Here are some examples of the free software programs available for monitoring and sending the various digital communication modes. They require an HF LSB/USB receiver, a lead to connect the audio output to the microphone input of the PC sound card, together with the appropriate software.

       (CW) Morse Code

International Morse Code is the earliest digital mode and is referred to as 'CW' in Amateur Radio jargon because a continuous wave is turned on and off to form the elements of the Morse Code characters. Standardized sequences of short and long elements are used to represent the letters, numerals, punctuation and special characters of a given message in a rhythmic manner designed to be read by humans without the need for decoding devices.

This was the original method of sending radio messages. However the United States Coast Guard ended the use of Morse Code transmissions in its maritime communications service in 1995, and UK radio amateurs haven't had to learn Morse Code to obtain their license since July 2003. Despite this Morse Code has refused to die away for the following reasons:-

  1. As A Distress Signal - Western nations held a convention in 1906 to agree upon a single signal to ask for help that could be used anywhere in the world. Germany's idea won, a simple and elegant string of three dots, followed by three dashes, followed by three dots. All of the acronyms attributed to the letters, including Save Our Souls or Save Our Ship, were made up after the distress signal came into use to fit the SOS letter arrangement, making them what have come to be called backronyms. The distress signal "...---..." can be sent quickly and easily and is hard to misinterpret, and went into effect on July 1, 1908.

    In emergencies it can be sent by any means that can be turned on and off such as horns, whistles, torches, mirrors flashing sun light, tapping on pipes etc. The SOS letters can even be marked out on the ground.

  2. As A Fault Finding Aid - Engineers often use Morse as an enhanced form of beep code built into their equipment to aid fault finding. Many Nokia cellphones even have an option to beep either "SMS" standing for Short Messaging System or "CONNECTING PEOPLE" in Morse Code as an audible alert for the reception of a text message.

  3. In Amateur Radio - Many radio amateurs still use Morse Code because it only requires simple transmitters/receivers which are cheap and easy to build. The transmissions occupy very little bandwidth making them relatively easy to filter out from the background noise on reception so that inter-continental communication can be achieved with very little power (e.g. 10 Watts). Also in the Morse Code world there are many standard abbreviations which make it possible to exchange basic information between operators who do not speak the same language.

    Morse Code also remains popular because it presents a challenge. Fortunately there are various software programs and apps. freely available to assist in the learning process. The speed of Morse Code is measured in words per minute (WPM), while fixed-length data forms of telecommunication transmission are usually measured in baud or bits per second (bps). The North Cheshire Radio Club can give advice and practice, and even provide certificates of proficiency starting at 5 WPM.

    There are a number of programs and apps. available that can translate strong Morse Code signals under favourable conditions. The human ear is very good at filtering out the pulses but it is more problematic for devices to distinguish the spaces between the pulses from the variable background noise. The digitised signals designed for machines usually get over this problem by using one tone for a mark and another for a space, and have evolved to include additional coding to allow a degree of error correction on reception. This renders them unintelligible to the human ear.

       (RTTY) Radio TeleType

RTTY is one of the oldest automated modes and traditionally uses the Lower Side Band, whilst almost all the other digital modes use the USB. The typing speed is usually 45.45 or 50 baud corresponding to about 66 words per minute. The signal is digitised by switching between two audio frequencies. There is no error correction so that when the propagation conditions are poor a certain amount of guesswork is required when reading the message.

RTTY at 45 baud with an 850 Hz frequency shift
Spectrum of a RTTY transmission, 45 baud, 850 Hz frequency shift

       PSK 31

PSK31 was developed in the 1990s as an improvement over RTTY and is encoded to contain redundant information which allows a degree of automatic error correction on reception. The overall signal is very narrow using two carriers spaced 31.25 Hz apart which can be clearly seen when no data is being carried.

Spectrum of several PSK31 signals
Spectrum showing a number of PSK31 signals

       Decoding PSK 31

The following image shows the PSK31 communication program bundled with the 'fldigi' software, whilst the following image shows the out from 'supersweeper' which is part of the 'Hamdradio deluxe' suite and can simultaneously decode numerous PSK31 channels at the same time.

PSK_31 communication program
PSK_31 communication software

Simultaneous decoding of PSK31 signals
Supersweeper software simultaneously decoding several PSK31 signals

       Weather Facsimile

Very few amateurs now transmit using FAX having gone over to SSTV, but there are regular transmissions for maritime use sending black and white weather maps.

Weather program
Weather Facsimile display - e.g. HAMFAX

       Slow Scan Television (SSTV)

This is the method now commonly used by amateurs to send photographs in colour or black and white. There are various modes in use but a slow sequence of tones sent at the beginning of each picture enables the software to automatically select the correct one.

MMSSTV picture
SSTV picture received by software such as MMSSTV, EasyPal or qsstv.

        Low Power Communication

How far can one communicate with low power or poor propagation? Some of the techniques employed to enable signals to be dug out from below the noise level are demonstrated in the projects listed here:-

WSPR picture
The WSPR screen

WSPRnet picture
The WSRPnet map

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