Communications In The Outback

What form of communications do you take with you when you travel in to the outback? The next few pages should help you decide what is best for you and your trip. It is a great misconception that a digital mobile phone will work in the bush right? Wrong! Digital mobile phones may have 94% coverage of Australia’s populated areas with the emphasis on populated areas. 6% of populated Australia is a large area not to mention the rest of our vast unpopulated continent the Australian outback. So what form of radio communications do you look at? The following information should help by explaining the 4 main types of communications in use in the bush.

 

1. CB AM/SSB (Some times called 27 Meg) 27 MHz

 

2. HF (Some times called RFDS or Flying Doctor Radio) 2-30 MHz

 

3. UHF CB 477 MHz

 

4. Sat Phone (Satellite Telephone)

 

 It should be noted that none of the above units can communicate with another style of radio ie. A 27 MHz CB can not talk to a UHF or HF Radio and visa versa. So if a vehicle in your convoy only has a UHF then all other vehicles in the convoy must have a UHF radio if the wish to communicate with that particular vehicle.

 Now to explain in more detail the different units and what you should take:

27 MHz "CB"

A lot of us have at one time or another either owned or used a 27 MHz radio, boasting 18 channels back in 1977 when they first became legal in Australia. For a limited we saw 23-channel CB's in Australia, but that was soon replaced with the current 40-channel system.

 27 MHz falls into the upper range of the HF radio band spectrum, but the range for the humble AM CB radio is limited to line of site and can vary from as little as one kilometre to approximately ten kilometres in flat country.

 Since the signals are transmitted using Amplitude Modulation (AM) the sound quality is poor when compared to UHF CB, which uses Frequency Modulation (FM). The power output of an AM CB radios is four watts. Channel 8 on the AM band is used nation wide as the highway channel, but the majority of trucking companies now use UHF units.

AM CB radios featuring single side band (SSB) have a much larger range than normal AM CB radios, and offer the user a lot more channels. There are three different AM SSB transmission types - AM CB mode (As Above), Lower side band mode (LSB) and Upper sideband mode (USB). Both LSB and USB offer an extra 40 channels each a total of 120 Channels. SSB compresses the transmission information into a more compact signal. Depending on the atmospheric conditions, the range can be a guaranteed minimum of 25 kilometres and can extend to approximately 50 kilometres. Occasionally even thousands of kilometres can be reached via "skip". This happens when the radio signal is reflected off a layer of the earths atmosphere known as the ionosphere. The ionosphere stretches out from an altitude of around 60 - 500 kilometres above the surface of the earth. Ultraviolet radiation from the sun forms positively charged ions and negatively charged electrons in the ionosphere. These electrons bend the radio waves, and if lucky, they will return to the earths surface. If you are not so lucky, they will either pass through or be absorbed by the ionosphere.

It is this chance of luck that makes AM SSB skip unpredictable, and therefore is not an appropriate system to use for long range emergency communications

. These radios have a 12-watt power output when transmitting in SSB Mode.

UHF

 A year after the AM CB radio was legalised in Australia, the uniquely Australian 477 MHz UHF radio was born.

 While using FM when transmitting, the quality of sound of UHF radios is much better than that of the 27 MHz AM CB's, while not being as susceptible to interference from foreign electrical sources.

 The range of UHF CB radios is limited to around a 50-kilometre line of site in simplex mode. In built up or heavy vegetated areas range can be limited to as little as 10 kilometres. When transmitting in duplex mode, the range can be increases to around 150 kilometres using public repeaters.

A repeater is simply two UHF transceivers connected back to back, situated in a location to provide an extension of the operating range of the UHF CB.

The repeater "listens" to 30 channels up from the allocated repeater channel and the retransmits the signal on the allocated repeater channel. Here are eight channels designated for repeater use as listed below:

Channel Input Output 1 31 1 2 32 2 3 33 3 4 34 4 5 35 5 Designated for emergency use 6 36 6 7 37 7 8 38 8

 To use a repeater, you must first switch your UHF CB to the desired channel (1 to 8), and then you must select DUPLEX or REPEATER mode. Your radio will now listen on the frequency you selected. When you operate the Press to Talk, your radio will automatically move up 30 channels to the correct repeater input channel. If you forget to select Duplex or Repeater mode, pressing the Press to Talk will result in you transmitting in the Repeater output channel and possibly causing interference to other users.

 Repeater channels are not to be used for single frequency (Simplex) communications in locations that are designated as repeater coverage areas.

 Repeater channels may be used for single frequency (Simplex) communications in areas where they are not allocated for repeater use. Channels 5 and 35 are dedicated for emergency communications only.

 You can hire either a handheld or in car UHF radio. Both styles have the maximum legal output power for UHF radios, which is five watts.

Because the range is limited with UHF, it is not appropriate for emergency use, but it is one of the most popular forms of mobile communication and is ideal in convoy situations with channel 40 being used nation wide as the highway channel with most truckies using this channel.

This is my first choice for all multi vehicle groups, or car to car communications, this makes all vehicles in the group able to communicate with each other as one large group. A great example of the use of a UHF is if the last vehicle in the group has a Flat tyre they can stop all other vehicles from leaving them behind. Or the lead vehicle can let the others know of dangers on the road ahead, wildlife ect.

For a list of repeater locations around Australia see our list Press Here

RFDS / HF

 Long distance HF radio transmissions operate via the same principle as AM SSB radio transmission using "skip" on the ionosphere, but the range of frequencies that are available to the HF band makes it far more dependable.

The ionosphere is continually changing during the day, from one season to the next and over a cycle of 11 years. During the day, there are four layers in the ionosphere, but at night there is only one layer, so a transmitted radio frequency that could be bent and returned to the earths surface at noon, may pass straight through the ionosphere at 9 PM when the is only one layer. This is the reason why HF radio offers a large range of frequencies to the operator (from 6 to 600 channels) for long-range communication. When the ionosphere has only one layer at night, a low frequency is more suitable and during the day when there are more layers, a higher frequency is more suitable.

Sky wave transmission is one way that radio signals bounce off the ionosphere but there are two other methods of transmission available to HF radios – ground wave and direct wave.

 The ground wave transmission travels near the ground and is good for transmission distances of around 100 kilometres over land. The direct wave transmission is only good for line-of-sight transmissions.

HF radio is excellent for emergency communications,
With a direct link to the Royal Flying Doctor Service (RFDS) or the VKS-737 Network.

Another feature of the HF radio is that you can hook up to the telephone system to call anywhere in Australia. The first system available to HF radio users was Radphone “ the name being derived from the term radiotelephone. To place a Radphone call you contact an operator and the operator will connect you to the telephone number that you have requested. You can also receive incoming calls to your HF radio that are broadcast on a traffic list each hour, which you can monitor to see if there is a call waiting for you. If there is, you then contact the operator who will put you through to the caller. This service is available through the Royal Flying Doctor Service and the Australian National 4WD Radio Network

The Australian National 4WD Radio Network is a Public Benevolent Institution established to provide communications and safety logging services for members of the public traveling and working in the remote areas of Australia. The Network also provides services for users of aircraft and marine pleasure craft.

The Network was established in 1993 following a request from the Australian Communications Authority (formerly the Spectrum Management Agency) in Adelaide with the view to setting up an Australia Wide 4WD HF Radio Network for use by Outback travelers.

The need for a dedicated 4WD Radio Network stemmed from an Australian Communications Authority decision to clamp down on the illegal use by Four Wheel Drivers of Outpost Radio Frequencies such as 5300kHz, 5360kHz, 5410kHz etc. to make contact from their homes to others traveling in the Outback. At times Emergency Calls through RFDS bases had been disrupted when "illegal" users had refused to clear the channels when requested to do so by the base operators.

The Network commenced operation in November 1993 with a single frequency of 5455kHz with a base station located at Hilton near Adelaide. Over the next couple of years the Network was expanded with the addition of 4 extra frequencies and also additional base stations located in strategic locations around Australia.

This is some of the services offered by Australian National 4WD Radio Network:

Satellite Phones

 Communicating from the Outback is no longer limited to the humble radio. You can use an international system of geostationary satellites that are orbiting the earth. Satellite phones (SAT Phones) are able to offer you direct dial voice, fax and data communications from anywhere in Australia to almost anywhere in the world.

Sat Phones today are now available as a hand held unit, similar to your current mobile phone, just slightly larger. The GlobalStar range use both the Mobile GSM or CDMA Networks as well as the Globalstar Satellite network.

The operation of a SAT Phone is as simple as using a mobile phone. The most important thing to remember is to aim the antenna at the satellite. There are also units that are available with vehicle mounted antennas that can be used on the move. Calls are charged via a Connection Fee, Monthly Fee and Per-Minute usage rates.

Conclusion

 The point to mobile communications is to choose what system is correct for your needs. As you can see, keeping in touch can cost from as little as $100 to well over $5000.
If you intend to travel in the harsh but beautiful Outback of Australia and wish to be able to contact someone in an emergency, there are only 2 reliable options for you. You can either buy or hire a HF radio or Sat phone. If you hire either a HF (RFDS) radio or a sat phone the cost divided amongst your traveling companions makes for very cheap security. After all how much is you or your family's life worth? For vehicle to vehicle communication the UHF is the best option for clear easy to understand communications. In two years of selling 4wd accessories I only know of one 27 MHz CB sold to at least 150 or more UHF Radios the style most people now carry for their vehicle for their car to car communications.