 FILES:

cas2.ps.gz
 FORMAT:

gzipped postscript.
 AUTHORS:
 J. O. Coleman
 TITLE:

Choosing Nonuniform Tap Spacings for a
TappedDelayLine Filter
 ABSTRACT:

The family of frequency responses that can be
generated by adjusting the weights on a
tappeddelayline filter with nonuniformly spaced taps
is just the span of a basis set whose elements are
arbitrary (as long as linear independence is
preserved) frequency shifts of the characterizing
function of the set of delays. The characterizing
function is just the frequency response that results
when uniform weights are applied at those delays. If
the delays are chosen to provide a unimodal
characterizing function with low sidelobes
(probability theory provides one approach), then it
tends to be easy to approximate a desired frequency
response from linear combinations of various frequency
shifts of the characterizing function. If the
characterizing function is severely multimodal, it is
relatively difficult to get the linear combination of
the characterizingfunction shifts to approximate a
desired response. Though this intuition about what is
possible comes from visualizing the manual
construction of the desired response, the conclusions
reached generally also predict the degree of success
that will be obtained from an optimal design of the
filter weights. Further and most importantly, the
characterizingfunction idea offers guidance in the
choice of the delays themselves.
 STATUS:
 The final version published in the IEEE
Transactions on Circuits and Systems II: Analog and Digital Signal
Processing in April 1996 was slightly revised from this earlier
preprint version.
 DATE OF ENTRY:

August 11, 1993. Status updated November 12, 1995.