Accession Number:

ADA422819

Title:

Analysis of Statistical Performance Measures

Descriptive Note:

Final rept. 1 Oct 2002-31 Dec 2003

Corporate Author:

PURDUE UNIV LAFAYETTE IN

Personal Author(s):

Report Date:

2004-05-12

Pagination or Media Count:

13.0

Abstract:

When only a limited number of snapshots is available for estimating the spatial correlation matrix, a low-rank solution of the MVDR equations, obtained via a small number of iterations of Conjugate Gradients CG, can yield a higher SINR than the full-rank MVDR beamformer. A primary issue addressed in this effort is whether the unity gain constraint in the look direction should be enforced a-priori via the use of a blocking matrix, constituting Steering Dependent Conjugate Gradients SD-CG, or effected a-posteriori through simple scaling of the beamforming vector, constituting Steering Independent Conjugate Gradients SI-CG. A major contribution was that the two methods yield exactly the same low-rank beamformer. This is an important result since the construction, and application to the data, of a blocking matrix for each look direction is computationally burdensome. A simplified expression for the power estimate obtained with the SI-CG beamformer was also developed. Extensive simulations were conducted to verify the efficacy of the theory. While it was known that the optimal number of steps of SI-CG varies with look direction, simulations presented here reveal that the optimal number of principal eigenvectors for the PCI beamformer varies substantially with look direction.

Subject Categories:

  • Theoretical Mathematics
  • Optics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE