Computers in amateur 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 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.
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.
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
Several logging and contesting programs are
includes a demonstration copy of Ham Log v3.1, a contesting and logging program
developed by Robin Gandevia VK2VN.
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.
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
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
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
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.
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
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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