NVIS Index

Near Vertical Incident Skywave (NVIS) transmits radio signals almost straight up (80 to 90 degrees), where it is reflected back down to the receiving station. This achieves dependable local area High Frequency (HF) communications within an area with a radius up to about 500 kilometres using frequencies between 2 and 10 or 12 Megahertz.

There is small group within EMRG that have expressed an interest to work on testing NVIS as a solution for emergency communications in Ottawa. NVIS is not new (WWII), but there is not a great deal of concise information on applying NVIS. The purpose of the EMRG testing is to determine how to best use NVIS in this area, including antennas and frequencies to use. If you are interested, send an e-mail to VE3OCE@RAC.CA

Understanding The Testing Required

Setting up a station and making a few "local" contacts does not prove NVIS as an emergency communications solution. Many antennas will allow local contacts, but the operator has little control of who, when or where they can contact. The purpose of NVIS testing, is to learn how to contact specific stations at specific times.

From the testing, EMRG can develop an NVIS deployment plan which allows consistent, reliable communications, regardless of the location, time of day or time of year.

NVIS provides a solution for situations where there is no repeater or repeaters have failed, and simplex VHF/UHF communications cannot link the two locations that need to communicate.

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