Range Measurement using Beam Coding Technique in Aircraft Landing System

The paper is focused on another approach for measuring the range or the distance from an aircraft to the runway in the landing phase of flight. The beam coding technique is used in the proposed landing system for the purpose of increasing the resolution and the accuracy in measuring both range and angle parameters. The introduced technique is based on a special parallel antenna to generate various shifted-angle beams and a Pseudo-Random Noise (PRN) code to index each of these different beams. The ground-based transmitter emits a large amount of these microwave beams toward the aircraft, and an airborne receiver uses a cross correlator to determine its deviation angle and the distance compared to the runway axis. In order to select a suitable waveform for transmitting, the paper evaluated different binary PRN codes based on the ambiguity function criteria and selected a small set of Kasami codes using at the transmitter. The beam coding technique and the proposed landing system are intended to be applied in aircraft navigation for the approach and landing phases of flight.