High Frequency (HF) Radios operate in the frequency range of 3MHz to 30MHz
HF radio is primarily designed to enable long distance mobile communication in areas where the mobile telephone network is not available. HF Radio is infrastructure independant useing the Ionosphere to refracft the radio signal rather rely on Satelites or Repeaters to achive long distance communications.
When all factors are at their optimum, worldwide communication is possible on a HF radio. At many other times it is possible to make contact across and between continents or oceans.
HF radio unit, can also be used to make telephone calls, for which you will need to subscribe to a direct dial service. Recent advances in technology have enabled email, fax, data and even GPS tracking functions to be possible via HF radio. The trade-off for gaining the ability to obtain free calls from your HF radio is learning how to use it. And for some people, it just isn't easy. The most obvious issue is that you cannot talk and listen at the same time, unlike talking on a telephone. This takes some practise and getting used to.
Codan Automated Link Management (CALM) is a new and very advanced feature in which the transceiver performs the channel selection operation automatically. The handset in most ways looks and operates like a mobile phone.