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Land Mobile Info

HF Land Mobile in Australia

Land Mobile HF radios are generally installed in 4X4 vehicles involved in outback travel.

HF radio has the amazing capability of transmitting over very long distances  (thousands of kilometres) with relatively small power output utilising modest vehicle mounted whip type antennas.

VHF /UHF radio is also used in 4X4 vehicles but these radios are only good for short distance communication of up to 20-30 kilometres in ideal (flat) terrain - although VHF / UHF is handy for shorter distance comms between 4X4 convoy verhicles it is inadequate for emergency comms as the transmit range is not sufficient to make contact with faraway Royal Flying Doctor or VKS-737 emergency networks .

There are various types of HF radio available on the market but in general terms they can be divided into 3 categories Land Mobile, Marine and Amateur (also known has Ham) HF radios. Each of these user groups has been allocated their own parts of the HF radio spectrum for their specific use.

A government approved HF Land Mobile HF radio must meet several mandatory requirements, that is, easy to use, minimal controls, 125 watts, upper side band only, with an emergency call facility. Generally a Land Mobile radio has a channel select, volume control, perhaps a clarifier, emergency call, on/off switch, and that’s it. Importantly however the land mobile HF has a function known as selcall which is mandatory if you wish to access RFDS (Royal Flying Doctor) and VKS-737 emergency networks or if you wish to access the radio telephone network whilst in the outback.  (IMPORTANT NOTE:  Marine and Amateur HF radios DO NOT have selcall - although ham radios are much cheaper than Land Mobile radios the lack of selcall functionality significantly limits the value of a ham / amateur radio in the outback as they are unable to access emergency networks or interface with the radio telephone network).

Marine HF radios are specifically constructed for the marine environment (enhanced waterproofing) and also have marine specific emergency calling features (such as DSC) that are not used in the outback environment (as marine HF radios are around the same cost as a land mobile equivalents there would never be a good reason to purchase a marine HF for a land mobile use).

Amateur / Ham HF radios are manufactured specifically for people who are into two way radio as a hobby - ie they are electronics and radio comms enthusiasts who set up their own radio transmitting stations (under government license) and communicate with similar enthusiasts around the world. HF ham radios in relative terms are cheap and bizarrely are packed with far more features and technology than the more expensive marine / land mobile  HF radio equivalents. It can be tempting to purchase a ham HF radio for land mobile use (because of the cheaper price - smaller size - high end functionality etc) but the lack of selcall functionality significantly restricts the usefulness of such a device in the outback. It is also noteworthy that more features equates to greater complexity (land mobile radios are far simpler to use) and that is also illegal to use a ham radio for a land mobile purpose.

It is not possible to buy a HF radio of any variety (land mobile, marine or ham) which also has UHF Cb capability. If you want UHF CB (handy for shorter proximity comms) then you must install a separate UHF CB and also a separate UHF CB antenna on your vehicle.

A Land Mobile radio HAS to be a rugged piece of kit because of the sometimes extreme conditions the radios are exposed to. There is an Australian standard stipulating the requirements, and the license conditions for the service mandate the use of a standard compliant radio. This Standard is the Radiocommunications (MF and HF equipment — Land Mobile Service) Standard 2003

Purchase a HF Land Mobile Radio set-up from us here 

A typical Land Mobile HF Radio installation

A typical installation consists of a radio (mic , manual, radio mounting bracket and power cable to car battery are typically included) and a HF whip antenna.

HF radio covers the spectrum from 0-30 megahertz. Land Mobile users are allocated small chunks of frequency (bands) within this range. A variety of chunks are allocated as different bands provide better long distance communications at different times of day. As a generalisation, frequencies below 10 mhz are generally better at night - whilst frequencies above 10 mhz are generally better during the daytime. Each chunk of frequencies allocated generally requires that your antenna be a different length to work efficiently. Obviously it is not practical to have 6 or 7 different length whip antennas on your vehicle so manufacturers have solved this problem by inventing "tapped" or "motorised" antennas.

A tapped antenna requires you to stop and get out of the vehicle each time you move from one HF band to another. By changing the tap on the antenna you are changing its electrical length and optimising it for the new band you have selected. A motorised antenna does this automatically - the motorised antenna receives a signal from the radio each time you change bands and adjusts its length via a small motor inside the antenna itself. 

A motorised antenna is more convenient (ie you can change bands whilst still mobile) but the motorised option is significantly more expensive and also more prone to failure because of its moving parts. We do not recommend motorised antennas because of their poor reliability and accordingly we do not sell them at this webpage.

A compromise between these 2 options (and it is our preferred arrangement) is to buy the cheaper and more durable tapped antenna and also install an antenna tuning unit. The antenna tuner is a box that goes between the HF radio and your tapped antenna. With this tuner box in line, for most frequency changes you can simply leave the tap on your antenna unchanged (at the tap used for the lowest HF frequency) and employ the antenna tuner for optimising the electrical length of your antenna. This means you have the advantage of not having to stop the vehicle when changing bands but also provides the additional advantages of lower cost (as compared to  a motorised antenna) and lower risk of antenna failure. In the unlikley event that you say roll your vehicle and your whip antenna is snapped or broken you also have the option of attaching a length of wire (at least 10 metres long) directly to the antenna tuner and throwing it over a nearby bush or tree. This temporary antenna arrangement will work just as well as you recently deceased whip antenna.
 

What are the benefits in installing a HF Land Mobile Radio

The RFDS, or Flying Docs, provide emergency medical service via HF radio, activated via radio via a two tone alarm. This alarm is initiated via the Emergency Button, and is a mandated requirement of an Australian Standard Land Mobile HF radio. Calling a RFDS base via voice on a RFDS frequency will most often not get a response as the base station is scanning many frequencies, looking for the emergency two tone audio. 

VKS737

This service was launched in 1992, under the title of the 4WD Radio Network. This non-profit benevolent association’s charter is to provide information and emergency services to travellers throughout Australia. Regular scheduled call backs are conducted twice daily from each base station located at Charters Towers, Alice Springs, Adelaide, and Perth, on their allocated frequencies. While skeds are not happening members are free to contact any other members using selcall, and/or contact base stations for information, or in the event of an emergency obtain assistance. The service also offers direct telephone interconnects to many businesses, e.g. Birdsville Garage and the SA Police. The morning and afternoon skeds are interesting listening when you are travelling, especially remote, as there is no better information on conditions than the actual guy bogged up to his axles!

Radtel

This is a commercial enterprise allowing you to make and receive phone calls with your HF radio. Note, you need selcall capability to use this service. This works by having the radio scan the Radtel frequencies. Persons wishing to contact you ring Radtel, state the radio selcall ID and an approximate location. The Radtel base then attempts to contact your radio via selcall, you know when this happens when the radio starts to “ring”. The base operator passes the contact details on, and then you “telcall” the person.

The Radtel Network also has a Message Service, Emergency Assistance, Vehicle position monitoring, Direct selcall contact to the RFDS and much more.

A new service has recently commenced called HFoz, this service has 5 carefully HF channels, ranging from 3 to 15Mhz. These frequencies have been (for the first time) approved for Voice and limited Data usage. This means that HFoz is able to provide limited email and SMS capability.

Bcon, this company offers GPS tracking via your HF radio. The newer radios offer a GPS interface, in that they can accept NMEA-0183 messages from GPS units. Once the position has been collected by the radio, you are able to send this position using the selcall functionality. You can also request the position of another radio via the GPS Beacon feature. Back to Bcon (www.bcon.com.au).

So what should I buy?

Unfortunately brand new land mobile radios are very expensive to buy - a new radio and antenna package can cost up to $5,000 which is outside the budget of all but the most dedicated 4X4 enthusiast. For this reason we offer quality used Land Mobile radios at this site which come with a full 12 month warranty. We also offer package deals involving radio and tapped antenna or radio, antenna tuner and tapped antenna.

You can find our full range of land mobile gear on our webpage right here

 

 

 

 

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