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Computers in amateur radio

Picture of computer being used as software defined radio

These days most Australian amateurs own a personal computer. Word processing and games are perhaps the most common activities performed on a home computer. However, a computer can be made to do many other useful things around the amateur shack.

This article gives a brief tour of some of the many ways in which a computer can support amateur radio activities. Coverage of each item is necessarily brief. However, it is assumed that the reader has access to the Internet and will be able to obtain further information and/or software from the websites listed.

What type of machine?

These days most Australian amateurs own a personal computer. Word processing and games are perhaps the most common activities performed on a home computer. However, a computer can be made to do many other useful things around the amateur shack.

This article gives a brief tour of some of the many ways in which a computer can support amateur radio activities. Coverage of each item is necessarily brief. However, it is assumed that the reader has access to the Internet and will be able to obtain further information and/or software from the websites listed (print article only).

What type of machine?

A machine such as a 486 or basic Pentium will serve well for most if not all of the functions described here.

Programs are required for most of the uses described. Advice on obtaining these programs is given later. Accessories such as a printer, modem and (possibly) sound capabilities add greatly to the computer's usefulness, and should be seriously considered.

Short wave listening

Would you like to sample HF reception without buying a short wave receiver? Or have you ever wondered what the bands sound like from the other end of the earth? If so, why not try one of the several 'web receivers' on the internet?

Web receivers are a HF radio receiver remotely controlled by a computer linked to the Internet. You type in the URL and get to hear an HF receiver through the Internet (providing you have a sound card installed). You can usually adjust the receiver's frequency, the mode of reception and the volume from your own PC.

Web receivers, though fun to play with, are not a substitute for owning your own receiver. Their main drawback is if another person wishes to use it and changes its frequency. Also, it can take several seconds for any frequency adjustment, that the user makes, to happen.

The short wave listening links section of the Radio Amateurs Canada website (http://www.rac.ca/swl.htm) has a section on web receivers.

Morse code

Morse Code can be transmitted and received by computer. All that is needed is the appropriate software and a simple interface unit that can be built at home. The main limitation of simple computer Morse decoders is when the signal is weak or buried in interference - the human ear will always do better.

Readers are referred to page 6 of December's Amateur Radio for an example of an easy to build interface unit for decoding Morse signals.

Software also exists for those seeking to practice their Morse skills. This can send text or random groups at a speed specified by the user. Links to webpages containing Morse-related software can be found at URL http://www.rac.ca/cw.htm.

Digital modes

Almost all operators of digital modes such as radioteletype (RTTY), slow scan television (SSTV) and packet radio now use a computer for sending and receiving it. These modes require a small interface unit between the transceiver and the computer along with some special software (eg Hamcomm for RTTY and Baycom for packet). The interface unit can either be very easy to build and use only a handful of components (eg a Hamcomm interface unit or a Baycom modem) or an advanced project (eg a packet radio TNC).

Packet radio was covered in Novice Notes for December 1995. However, Amateur Radio has carried few beginner articles on the other digital modes. The best way to get started on these digital modes is to approach another amateur who already has these modes set up. He will most likely be able to assist with software and show you circuits of interface units/modems.

Log keeping

It happens fairly often these days. You've just answered a call from a DX station. Without needing to wait for your transmission, he calls you by name and knows your location and when he last worked you. You are impressed and wonder how he can recall your details instantly. Your contact was just demonstrating one of the most useful applications for computers in amateur radio - that of amateur station log and callsign database.

Several logging and contesting programs are available. http://www.zeta.org.au/~richardm/hamlog.html includes a demonstration copy of Ham Log v3.1, a contesting and logging program developed by Robin Gandevia VK2VN.

Callbooks

If you bought the 1999 WIA Callbook, you will have noticed that you could send away for a copy on disk. The latest International callbooks are also available on disk.

There are some on-line callbooks available to anyone who has an Internet connection. To find them, just type 'callbook' into any search engine. The user just types in a callsign, and within a few seconds, the name and address of the licensee appears. Some Internet callbooks display extra information (eg an individual's e-mail address, URL or amateur radio interests) or allow you to make corrections. However, the author's experience is that at least for Australian listings, the free Internet callbooks are not as current as the WIA Callbook. You get what you pay for.

QSL cards

The use of programs to keep records of logs, countries confirmed and QSL cards sent and received was discussed earlier. Provided that you have a good printer and suitable software it is possible to print QSL cards on your computer. Some logging programs include a QSL label printing feature.

Satellite tracking

As is frequently pointed out in the AMSAT Australia column, ownership of a computer is a must if you are interested in amateur satellites. The main use of computers is in calculating the times that the satellite will be overhead, and thus be workable. Computers can also be used to control antenna headings - a feature particularly useful for satellite operation as both azimuth and elevation often have to be varied. Information and software can be obtained by joining AMSAT.

Grid squares

Amateur VHF/UHF operators often exchange four or six digit codes indicating their approximate location. These are called Maidenhead locator squares. The world is divided up into 324 squares based on latitude and longitude. Each square has a number. They are often more convenient to exchange on air than long place names.

If you know your latitude and longitude, it is possible to calculate your Maidenhead locator using a program developed by John Martin VK3KWA. You can also calculate the distance between any two squares and the correct beam heading for each station.

To obtain a copy of the program, send a 3.5" disk and a stamped addressed envelope to VK3KWA at the address given in the callbook. The program is very easy to use and will work on any IBM-compatible computer.

Automatic CQ caller

Those with a sound card in their PCs may wish to consider the possibility of turning their computer into an automatic CQ caller. All that would be required is a single recording of a 20 second CQ call and a means to repeat it every minute or so. For operating convenience, an interface box containing input sockets (for the sound input from the computer and the microphone), an audio output socket (to the transceiver's microphone socket) and possibly switching circuitry for the PTT line would be desirable.

Those more advanced could doubtless integrate the CQ caller with other functions such as transceiver control, beam steering and computer logging. This would make it possible to collect detailed statistical information on all aspects of station performance (eg CQ:contact ratios on various bands and to various directions, mean difference between signal reports sent and received, and more). Having this data would allow one to make a detailed assessment of the strengths and weaknesses of your station, particularly if other DXers your area were also collecting this data.

Drawing circuit diagrams

Readers of Repeater Link will be aware of the Draft Choice drafting program which can be used to draw schematic diagrams. The author's experience of such programs is that they are only justified if you do a lot of drawing and/or are willing to invest considerable time in learning to operate them properly.

An alternative approach for those who only have an occasional need to draw circuits is to use MS Paintbrush. This comes standard in any PC, so extra software is not required.

Though drawing a circuit with MS Paintbrush takes longer than drawing the same diagram on a sheet of paper, the finished result can look quite professional. All schematics on Novice Notes Online were drawn with MS Paintbrush. The large size of Paintbrush's .BMP files can be reduced drastically by converting them to .GIF files by using a converter such as Image Convert. The result is diagrams that are clear, easy to read but quick to load. MS Paintbrush is used for all schematic diagrams on this site.

Interference

It can be difficult to get computer equipment and radio equipment to operate together harmoniously. Radio transmitters can cause interference to computer systems - when using an automatic CQ caller on 10 metres one day, the author heard his recorded voice come through the modem while he was trying to log on to the Internet. Computers can also interfere with radio and TV equipment and, in extreme cases, make them unusable.

The first step to treating interference is to isolate the source of the problem. For example, does the interference go away when the modem or monitor is turned off? It can be wrong to assume that just because something is switched off, it is incapable of causing interference. The author has a Canon BJC210SP printer that interfered with HF reception even when the computer was not being used. The solution was to unplug it from the wall when it was not being used.

Poor quality, badly shielded connecting cables can sometimes radiate interference. The cable between the computer and the monitor can be particularly troublesome.

This article appeared in Amateur Radio February 1999. No updates have been made and it appears solely for historical interest.

 

 

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