Robust Radar Altimeter Processor

Abstract

Accurate nadir altitude information is a critical requirement for the precise and safe landing of an autonomously guided vehicle. Radar altimeter (RA) is well suited to provide precise height Above Ground Level (AGL) under the worst environmental conditions viz engine plumes, dust, cloud-covers, etc. The problem of precise nadir altitude estimation using a single RA system configuration under a wide range and attitude variation of ±25° is a challenging and open issue. The wide antenna beam is necessary to get adequate return power from the ground to measure the altitude under the influence of a wide range of attitude variations. Under the circumstances, the major problem of the existing methods for long-range measurement along with wide attitude variation is that they easily lose the current altitude value or require a long tracking time. This paper presents the design of a novel robust RA-processing algorithm, the design and implementation of high-performance processors, architecture details, and salient performance features. This digital Radar Altimeter’s high throughput processor performance has been validated via extensive lab tests and field tests and achieved excellent performance during the actual Landing of ISRO’s autonomous Re-usable Launch Vehicle (RLV) mission under wide attitude variation.