RadioScanning
RadioScanning
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B'cast/Shortwave
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Scanning
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Outback/Marine
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CB
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Amateur
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Projects
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Scanning
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Radio
scanning 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. A scanner 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.
Contrary 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. Update August 2006: This page now exists mainly for historical purposes. The use and spread of digital encryption technologies means that the scanning as a general hobby has all but finished. In cities like Melbourne, it is no longer a case of buying a scanner, punching in a few frequencies and picking up the police. Tomorrow's scanner users will either be those with special listening interests (eg aircraft or amateur radio) who still use analogue FM or people with a technological interest in modern digital communication systems. Such changes are not without precedent; many years ago police and fire could be heard on a modified AM broadcast receiver before moving to the 'exotic frequencies' of VHF and then UHF.
The following 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. H F 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 23cm band Notes: 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. This includes mobile phones and most modern cordless phones. 3. Frequencies higher than 1300 MHz require specialised receiving equipment and antennas. Frequencies below 30 MHz are covered by short wave receivers.
Scanners 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 20, preferably 50), a search function and a full-sized frequency display. Never buy a scanner offering less than this unless reception of a handful of known frequencies is all that is required. Also note that the cheaper units do not always cover the VHF airband. Under $300 models such as the Uniden Bearcat 57XLT, Uniden Bearcat 120XLT (both handheld), or 248XLT (home unit) are recommended as 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. A scanner 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: Same function as the similar control on a transistor radio. 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. Note that not all scanners have this feature. Hold: Prevents scanning from resuming, even if activity has ceased. WX: Weather button. In North America pressing this allows reception of a weather information service. This button has no useful function in Australia. Some scanners 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 and searching.
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. Most 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 Ό 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. The main disadvantage with outside antennas is when you're using them plugged into handheld equipment. If you live in a metropolitan area, strong signals can overload the receiver and spoil reception on other frequencies. The most practical solution is to use a high-quality base station scanner. However you could also try adding an RF attenuator (to cut down the strength of received signals) or an RF bandpass filter (to make the scanner more selective).
Frequency guide: A frequency book or CD 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 published by and are available from MAK Agencies. For information in electronic form, try the Uniden Australia website or the radiocommuncations database on the Australian Communications and Media Authority site. External speaker: Can provide better sound than the scanner's inbuilt speaker. One with a 3.5mm plug will suit nearly all scanners. Carry case: Offers protection for handheld scanners.
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 active popular frequencies (from your frequency guide) 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 here. 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.
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 by police in NSW, ACT and Tasmania. Only advanced scanners like the Uniden 780XLT can follow trunked transmissions. For more details see the links below.
The following are some useful scanner links: Australian Communications Authority Online Radio Frequency Database Melbourne Metropolitan Scanning Scanner Monitoring in South Australia
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