Adaptive Filters
and Wiener
Filter
Digital Filters
Digital Filters
Note that in a digital filter, the signal is represented by a sequence of
numbers, rather than a voltage or current.
The following diagram shows the basic setup of such a system.
Order of a Digital Filter
Example (1): y
n
= x
n
•
This is a zero order filter, since the current out
put yn depends only on the current input xn and
not on any previous inputs.
Example (2): y
n
= Kx
n
•
The order of this filter is again zero, since no p
revious outputs are required to give the current
output value.
Order of a Digital Filter
Example (3): y
n
= x
n-1
•
This is a first order filter, as one previous input
(x
n-1
) is required to calculate y
n
. (Note that this
filter is classed as first-order because it uses
one previous input, even though the current
input is not used).
Example (4): y
n
= x
n
- x
n-1
•
This is again a first order filter, since one
previous input value is required to give the
current output.
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