About HF SSB radio communications To gain a better understanding of the unique benefits HF Communications can provide, we have created a HF Communications overview video tutorial and a HF Network setup examples video tutorial. HF Communications overview video tutorial

This tutorial explains the basics of HF propagation and how HF SSB communication works.
HF Network setup examples video tutorial

This tutorial gives examples of how to setup HF Communications stations and explains how they can be used to create a complete non-satellite based communications network for use in remote areas where there may be no other infrastructure.

About HF propagation
>> Ground-wave which travels directly from the transmitting antenna to the receiving antenna following the contours of the earth.

Generally speaking, ground-wave is used to communicate over shorter distances usually less than 50km. Because ground-wave follows the contours of the earth, it is affected by the type of terrain it passes over. Ground-wave is rapidly reduced in level when it passes over heavily forested areas or mountainous terrain.

>> Sky-wave which travels upward and at an angle from the antenna, until it reaches the ionosphere (an ionised layer high above the earth's surface) and is refracted back down to earth, to the receiving antenna.

Sky-wave is used to communicate reliably over medium to long distances up to 3,000km. Whilst the nature of sky-wave propagation means it is not affected by the type of terrain as in ground-waves it is affected by factors involving the ionosphere as described below.

>Factors which affect HF/SSB communications
>> Frequency selection is perhaps the most important factor that will determine the success of your HF/SSB communications.

Generally speaking the greater the distance over which you want to communicate, the higher the frequency you should use.

Beacon Call, a Selcall (selective call) function built into the Barrett 2000 series transceiver, makes finding the correct frequency to use easy. Beacon call is based on the network transceivers all having a selection of frequencies that will accommodate most ionospheric conditions. When in standby the network transceivers scan these frequencies waiting for a call (Selcall or Beacon Call) from another transceiver.

The transceiver wishing to check for the best frequency to operate on sends a Beacon Call to the station he wishes to contact. If his call to the other station is successful he will hear a revertive call from the station he is calling, indicating the channel he selected was suitable for the ionospheric conditions prevailing. If he does not hear this revertive call or it is very weak, he tries on another channel until a revertive call of a satisfactory signal strength is heard.

>> Time of day As a rule, the higher the sun, the higher the frequency that should be used. This means that you will generally use a low frequency to communicate early morning, late afternoon and evening, but you will use a higher frequency to cover the same distance during times when the sun is high in the sky (e.g. midday).

You will need to observe the above rule carefully if your transceiver has a limited number of frequencies programmed into it, as you may only be able to communicate effectively at certain times of the day.

>> Weather conditions Certain weather conditions will also affect HF/SSB communications. Stormy conditions will increase the background noise as a result of 'static' caused by lightning.

This background noise could rise to a level that will blank out the signals you are trying to receive.

>> Man-made electrical interference Interference of an electrical nature can be caused by overhanging power lines, high power generators, air-conditioners, thermostats, refrigerators and vehicle engines, when in close proximity to your antenna.

The result of such interference may cause a continuous or intermittent increase in the level of background noise.

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Tactical operations rely on HF radio to provide secure and highly reliable communications over long distances in demanding applications and environments.

Barrett HF radio is secure, autonomous and resistant to jamming than other communications mediums. Configurable as a manpack, mobile vehicle or fixed base station all Barrett HF systems use the same keypads and front panel, specifically designed for users who do not have, or need, a lot of training.
Low band VHF radio communications is specially designed for multi-role tactical military and security applications, communications where communication between operators is up to 5km.

Barrett VHF is configurable as a 5 W Hand portable radio, 25 W Manpack radio, 50 W Mobile, 50 W Base station and 50 W Re-broadcast system for range extension or for use in mountainous regions where typically VHF communications is restricted due to the terrain.
Barrett offers a range of interoperability solutions between radio and telephone networks, HF and VHF radio systems and options that are radio and crypto agnostic.

These solutions can enable users to re-commission legacy products with latest technologies or enable collaborative forces to communicate with little need for additional infrastructure.
Our turnkey network design team work with the client’s system requirements and produce an initial technical proposal which, once client approved, develops into the detailed technical document with system manuals and full installation programs.

Each turnkey solution is designed specifically for the client, with some solutions incorporating remote sited HF transmitters and receivers linked to landlines or microwave communications, operator consoles, custom built interfaces and MIL-STD HF data systems including 5066 stack based systems.