is a recreational activity enjoyed by thousands of Australians. Scanners are special radios that receive signals not
audible on standard AM/FM sets. Ambulances, police, fire services, emergency,
commercial, aircraft, security, amateur and CB users are just some of the signals available on a scanner around the clock.
user hears news as it happens, hours before it appears on the evening news bulletins. At any one time, they could be
monitoring the local McDonald's drive-through, listening to train drivers, hearing TV station crew set up an OB or tuning
into chatter from amateur and CB operators.
to widespread belief, scanning is perfectly legal. However, you should not use information obtained from listening for
commercial gain or criminal activity. Monitoring phone conversations on your scanner is also forbidden. Apart
from that, you can pretty well scan as you please, though discretion is advised when using scanners in public. For instance,
being an 'ambulance chaser' and fronting up at accident scenes, hindering emergency services is an extremely silly thing to
do. Genuine scanner enthusiasts don't want to give politicians an excuse to ban or restrict the hobby, as has occurred
in other countries.
list, though not exhaustive, gives an idea of the variety of users active on the upper HF, VHF and UHF radio spectrum. Some of the ranges given may be useful when using the scanner's 'search' feature.
26.965 27.405 MHz 27 MHz CB RADIO
27.145 MHz Children's walkie-talkies
27.680 27.980 MHz 27 MHz Marine radio
28.000 29.700 MHz Amateur ten metre band
29.700 30.000 MHz Remote control models
V H F
30.075 30.300 MHz 30 MHz cordless phones
35.000 40.000 MHz Two-way radio
40.68 MHz Paging systems
46.000 52.000 MHz TV channel 0
49 MHz approx Baby monitors
50.000 54.000 MHz Amateur six metre band
55 MHz approx Low-cost FM walkie talkies
56.000 70.000 MHz TV channels 1 & 2
70.000 85.000 MHz Two-way radio (VHF low band)
76.000 MHz approx Ambulances
85.000 92.000 MHz TV channel 3
88.000 108.000 MHz FM broadcast band
94.000 108.000 MHz TV channels 4 & 5
108.000 137.000 MHz Aircraft band
121.500 MHz Emergency beacons (EPIRBs)
136.000 MHz approx Weather satellites
137.000 144.000 MHz TV channel 5A
144.000 148.000 MHz Amateur two metre band
148.000 MHz approx Radio paging services
148.000 174.000 MHz Two-way radio (VHF high band)
152.000 MHz approx Ethnic broadcasting services
156.025 156.425 MHz VHF Marine Radio
156.800 MHz Marine distress safety & calling
174.000 222.000 MHz TV channels 6-11
222.000 400.000 MHz Defence communication
243.000 MHz Emergency beacons (EPIRBs)
U H F
400.000 420.000 MHz Two-way radio (UHF)
413.000 MHz approx Ambulances
415.000 MHz approx Rail
420.000 450.000 MHz Amateur 70cm band
450.000 520.000 MHz Two-way radio (UHF)
468-470 MHz approx Police
476.425 477.400 MHz UHF CB RADIO
526.000 575.000 MHz UHF TV channels 28 - 34
575.000 - 582.000 MHz Amateur TV (some cities)
603.000 820.000 MHz UHF TV channels 39 - 69
820.000 1000.000 MHz GSM and CDMA mobile phones
820.000 1000.000 MHz Two-way radio trunking systems
820.000 1000.000 MHz Spread-spectrum cordless phones
1240 1300 MHz Amateur:
1. Typical users of two-way radios include taxi companies, couriers, security personnel, factories, tradesmen, shopping
centres, public transport services, local government and more.
2. GSM, CDMA and spread-spectrum communications cannot be received on normal scanners.
3. Frequencies higher than 1300 MHz require specialised receiving equipment and antennas. Frequencies below 30 MHz are
covered by short wave
come in handheld, in-car or home station configurations. Most tune several frequency segments between 25 and 1300 MHz.
The more expensive units have fewer gaps in received frequencies, provide more memory channels, and offer the ability to track
transmissions from trunked radio networks.
It is suggested that beginners start
with a fairly basic scanner. Though it might not cover as many frequencies as
a larger unit, they are easy to use and can provide hours of listening enjoyment. The
main things to look for in a scanner are sufficient memory channels (at least 50) and a search function. Never buy a scanner offering less than this unless reception of a handful of known frequencies is all that
is required. Models such as the Uniden Bearcat 120XLT (handheld) or 248XLT (home
unit) are good starter units.
More sophisticated scanners cover more
frequencies and have more memory channels. Other features offered include
a tuning knob, selectable channel steps and ability to track trunked transmissions (see later). The greater frequency coverage allows reception of a wider range of signals that cannot be received on
cheaper units. More memory channels is always an advantage, particularly for
users in major cities. Better scanners (particularly those built for home
use) also have improved rejection of strong nearby signals. Strong signal rejection
is an issue on cheaper handheld units that can overload if connected to a home station antenna in urban areas. A typical example of a high-end scanner suitable for home and car is the Uniden 780XLT.
has a few more controls than a normal AM/FM radio. The following explains their
function. Note that there are some variations between brands and models.
· Off/on/volume: Self-explanatory.
· Squelch/Mute: Silences the receiver in the absence of a signal or when scanning. Set this control to the point where the noise just stops.
· Manual: Makes the scanner ready to accept a frequency keyed in by the user.
· Numerical keypad: Allows frequencies to be keyed in manually.
Also useful for setting search limits and other functions, depending on the scanner.
· E: Enter button. Press this after keying in a frequency.
· Scan: Allows the set to automatically tune through stored frequencies (memory channels). When a channel is busy the scanner will stop. Scanning will
resume when activity ceases.
· Limit: Allows operator
to set lower and upper frequency limits of a search (see below).
· Search: Pressing
this causes the scanner to tune across every channel between pre-set lower and upper limits.
Searching is useful when you only know the approximate frequency of something you wish to listen to.
· VFO: Allows manual tuning across a range of frequencies, much like an ordinary AM/FM broadcast receiver. On some scanners the same control may be used for other functions, such as selecting
preset memory channels.
· Hold: Prevents scanning from resuming, even if activity has ceased.
· WX: Weather. In North America pressing this allows reception of a weather information service. This button has no useful function in Australia.
have additional buttons missing from the above list. Others use a menu system
so that a large number of functions can be selected from a small number of controls on the front panel. With any scanner, the user should master the basic skills of entering a frequency, storing memories, scanning
The short whip antenna supplied with
handheld and base station units is adequate for local reception (between 5 and 30km).
However a better antenna increases the receiving range and variety of signals heard, especially from radio users not
operating via repeater stations.
Fitting a longer whip to a handheld scanner
can improve reception, particularly at lower frequencies. Roof-mounted mobile
antennas are a good idea if using a handheld scanner in a vehicle. Handheld scanners
use a standard BNC connector and suitable mobile scanner antennas and mounts are widely available. Mounting is similar to UHF CB antennas, but less critical unless long-distance reception is required.
If listening at home, an antenna mounted
outside is required for best reception. If even performance in all directions
over a wide range of frequencies is required, a discone antenna is a good choice. A
discone is able to receive signals up to 20-100 kilometres away. Longer reception
ranges are possible if using yagi or log-periodic beam antennas. As these are
directional antennas, a rotator is required. Beams are particularly recommended
for listeners in urban fringe or rural areas where signals are weaker.
It is suggested that those only interested
in tuning a narrow range of frequencies obtain an antenna for this range rather than use a broadband antenna such as a discone. This is because the narrow band antenna may have gain over the discone and provide
better reception. Mobile or base station antennas made for transmitting
can be particularly useful here. For instance a 27 MHz CB base station antenna
will provide good reception between 26 and 30 MHz. An antenna designed
for UHF CB will do well thirty megahertz either side of 477 MHz. A 5/8 wavelength
whip made for 144 MHz will cover VHF high-band two-way radio signals, and possibly the aircraft band as well. If a shorter antenna is required, a ¼ wave whip cut for 160 MHz will provide reception on both VHF high-band
(144-174 MHz) as well as UHF frequencies around 480 MHz.
The best antenna in the world can be
let down if poor antenna cable is used. Thin feedline can lose half to three-quarters
of the signal before it reaches the scanner! Cable loss gets worse with increasing
frequency and is particularly serious above 400 MHz. If most listening
is in the VHF range, and cable lengths are kept to ten metres or less, RG58 cable will suffice. On the other hand, if the cable run is much longer, or your main interests are in the 400, 500 or 900 MHz
bands, a thicker cable such as RG213 is preferred.
Frequency guide. A frequency book is the scanner user's most useful
companion. It is particularly useful for the newcomer who wants some 'sure-fire'
frequencies to start off with, and/or wishes to listen to a particular user. Books
vary widely in content some are simple lists of frequencies, while others have more detailed information by region. Frequency books are available from suppliers such as Dick Smith Electronics and Tandy. Radiomag carries frequency lists and articles on scanning; look for it at newsagents each month.
· External speaker. Can provide better sound
than the scanner's inbuilt speaker. One with a 3.5mm plug will suit nearly all
Carry case. Offers
protection for handheld scanners.
Using a scanner
With any scanner, the user should master
the basic skills of entering a frequency, storing memories, scanning and searching.
These procedures are explained in the instruction book that comes with the scanner.
Because some functions are not self-explanatory, secondhand scanners without instruction books should be avoided.
Start by entering a few popular frequencies
as memories and press scan. With any luck the radio will scan through the channels,
stopping when one is busy. Next experiment with using the 'hold' button. Also try searching between two limits. The
frequency range chosen should be one known to be active the above frequency table or a scanner frequency book will assist
After several sessions of listening,
write down your favourite frequencies, and divide them into groups such as fire, ambulance, amateur, CB, etc. Enter these under separate 'banks' in the scanner's memory. By
using the 'scan banks' feature on most scanners, the user can choose what they want to hear by simply selecting which bank(s)
they wish to scan.
What is 'trunking'?
Trunking is an advanced communications
system where the frequencies of multiple users are co-ordinated through a central control channel. This is done automatically without the need for the radio user to change frequencies. Trunking is used in all states, but particularly in NSW, ACT and Tasmania.
Only advanced scanners can follow trunked
This article was republished with permission for P.Parker
Peters web site is http://www.alphalink.com.au/~parkerp/radio.htm
Below is a list of some words or terms and
their basic meanings that you may come across during the pursuit of your hobby of radio communications scanning.
Simplex - a single frequency used for transmit as well as receive
Duplex - two frequencies used to relay transmissions
Watt - The
power output of a transmitter, the higher the Watts, the better the signal
Search - A facility in a scanner to look for other frequencies within assigned limits.
Priority - A regular sample channel that the scanner checks during scanning. This option will over ride transmissions on other
Lock out - allows the scanner to by pass the entered frequency
Squelch - cuts the amount of interference received
Program - allows the user to enter frequencies or use other options
Manual - by pressing this your scanner will step through to the next channel in the memory banks
Image - your
receiver will duplicate a false transmission on a frequency not being the genuine frequency
Birdie - an electronic noise being generated by the scanners circuits on certain frequencies
Earphone - an output stage of your scanner to be used for private listening
Attenuator - a function on your scanner to reduce the strength of an incoming signal
Audio - the
power output of the speaker, thus giving the sound
Discone - a broad band ariel
Active Antenna - an antenna with a boosted capability for listening to long distance transmissions
Telescopic - this is the type of antenna normally sold with your scanners. These may be adequate for strong local broadcast
Trunking Network - A radio network that uses multiple frequencies, voice transmissions change between these frequencies during conversations.
Repeater - used for relaying transmissions, this incorporates the term duplex
AM - amplitude
FM - frequency
VHF - very
high frequency, covers between 30 to 300 MHz
UHF - ultra
high frequency, covers between 300 to 3000 MHz
Modes - refers
to AM, FM
Band - relates
to a certain part of the Radio Frequency SpectrumACA
- Federal Government
department known as the Australian Communications Authority.