VHF (Very High Frequency)-AM Communications Equipment Selection and Installation Practices for Helicopters

摘要

This publication addresses the problems helicopter operators face when using VHF communications within typical operating environments where coverage by the network of ground stations may be deficient. This is of particular interest to IFR helicopter operators. The specific reasons why communications effectiveness can be limited in mountainous or remote regions, considering typical low helicopter operating altitudes, are reviewed. Recommendations to operators for improving the airborne VHF installation, and therefore improving its coverage capabilities, are presented. Several installation-related factors are addressed. These include the characteristics of the hardware, i.e. the transceiver and the antenna, and the characteristics of the installation, including antenna installation and resulting coverage pattern, the cable run, the effects of signal availability and ways of maximizing the capture of the available signal. A set of procedures is presented which allows operators to evaluate numerically the benefit in terms of signal strength or sensitivity they may expect given that they make specific improvements to a given actual, or planned, installation. (Author)