Comment on "Optimizing the Gains of the Baro-Inertial Vertical Channel"

Abstract

The authors concede that, in principle, aimpoint wander may exist due to either intensity modulation or angle wander. In that connection, the criticism of the discussion of the observations as illustrated in Fig. 6 is justified, in that the spikes in the error signal record marked e, f, and g may truly be aimpoint excursions due to interference of echoes from the target, and that the echoes need not necessarily originate from the terrain just because the direction from which they appear to come falls off the target. It is also true, however, that the error signals in the data presented in the paper are strictly products of angular error and signal intensity. It follows that the spikes in the error signal record may be due not to an aimpoint wander, in the sense of Mr. Howard's suggestion, but only to a sudden increase in echo intensity, as is our conclusion. The primary datum in support of this conclusion is that the spikes in the error signal record are always quickly damped. This is reasonably concluded to be due to the use of the AGC, if the cause of the spike is a sudden increase in signal intensity. There is no reason to expect such sudden damping if the spike is a true aimpoint wander. We thank Mr. Howard for his helpful and thoughtful comments.