Analysis of Correlated Noise in Airborne Magnetic Gradients for Unexploded Ordnance Detection

Abstract

In this paper, we examine several field tests of correlated helicopter noise and demonstrate that measured vertical gradients can offer signal-to-noise improvements of 4:1 in rotor noise and 6:1 in maneuver noise over comparable total field measurements for unexploded ordnance (UXO) applications. This translates into an additional [Formula: see text] in acceptable survey height or ordnance depth. Horizontal gradients, both transverse and longitudinal to the helicopter flight path, are also examined. These offer smaller signal-to-noise improvements over the total field (approximately 1.5:1) and have other disadvantages not found in the vertical gradient.