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Which radio type to buy?

HF Radio has the amazing capability of transmitting over very long distances  (thousands of kilometres) with relatively small power output utilising modest antenna systems.

VHF /UHF radio is  good for short distance communication of up to 20-30 kilometres in ideal (flat) terrain.

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 (frequencies) for their specific use.

Land Mobile (4x4) HF radio

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 often necessary 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.  

A Land Mobile radio HAS to be a rugged piece of kit because of the sometimes extreme conditions they 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.

(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 / marine radio in the outback as they are unable to access emergency networks or interface with the radio telephone network).

For short distance communication in the outback a UHF CB radio is also installed for communications with other vehicles in the convoy

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.

Marine HF SSB radio

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

(Important Note: as marine HF radios are around the same cost as a land mobile equivalents there would never be a good reason to purchase a land mobile radio for a marine application or vice versa. Land Mobile radios such as Codans / Barretts do not have DSC (refer below), are much harder to interface to marine radio peripherals such as antenna tuners and pactor modems.

Some mariners do use ham radios in their boats (because of the cheaper upfront cost) but  this is false economy as these radios will have a short life in a marine environment. Marine specific radios are designed at the factory to prevent the ingress of moist salty air into the unit - this salty air will quickly corrode the internals of a "non water-proofed" HF ham radio.

Ham radios also lack an important maritime feature known as Digital Selective calling (DSC). Should you experience a maritime emergency  in most cases you will be reliant on a commercial vessel to come to your aid. These days, very few commercial shipping vessels have a manned radio position. Thus, if you put out an SOS call using a traditional voice transmission, there will be no one manning the radio on the commercial vessel to action your emergency call. 

This is where DSC is vital. During an emergency, depressing the radio's Distress button for five seconds sends a "beacon type" digital call for assistance. This transmission contains your vessel's unique maritime mobile service identification number, the nature of the distress (undesignated, fire/explosion, flooding, collision, grounding, capsizing, sinking, disabled/adrift, abandoning ship, piracy attack, man overboard or epirb emission), the vessel's position (from a GPS interface) and the time of transmission.

Under the provisions of the GMDSS, coast stations, large ships and most commercial vessels on the high seas are equipped with DSC-capable HF SSB radios. When you "DSC beacon emergency signal" is received by such a commercial vessel it will  "ring an alarm" and prompt a member of the crew to attend to the radio. Your emergency information will scroll across the screen of the receiving radio on the commercial vessel.

Although a ham radio maybe sufficient for general chatting whilst on the water, a DSC equipped marine grade radio is mandatory  for emergency comms and will last years longer than the ham radio equivalent.

For short distance comms on the water (ie less than 20 kilometres) a VHF marine radio will be installed. It is not possible to buy a marine radio that has both HF and VHF frequency capability (ie you must have separate radios and separate antenna systems)

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 is noteworthy however that more features "bells and whistles" equates to greater complexity of use (as compared to land mobile / marine HF radios). It is also illegal to use a ham radio radio for a land mobile / marine purpose.




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