This paper deals with the problem of quadratic minimization subject to line
ar equality constraints. Unlike the standard formulation, we assume the mos
t general case of a possibly singular quadratic form, We explain that the e
xisting formal solution to this problem has several drawbacks, Our new appr
oach is free from most of these drawbacks. In particular, it has a simple i
nterpretation and is relatively easy to implement. The practical importance
of this result lies in its numerous applications: filter design, spectral
analysis, direction finding, and blind deconvolution of multiple FIR channe
ls, sere, we focus on the blind deconvolution application for which we pres
ent a novel solution with enhanced performance.