chapter  11
Distance measuring equipment
Pages 1

The previous two chapters have been concerned

with obtaining directional information for the

purposes of airborne navigation. In this chapter

we will look at a system that provides the crew

with the distance to a navigation aid. Distance

measuring equipment (DME) is a short/medium-

range navigation system, often used in

conjunction with the VOR system to provide

accurate navigation fixes. The system is based on

secondary radar principles, and operates in the L-

band of radar. Before looking at what the system

does and how it operates in detail, we need to

take at look at some basic radar principles.