Re: Basic info needed regarding filters (FIR)

On Thu, 22 Nov 2007 05:20:12 -0800 (PST), "faizankhan666@xxxxxxxxx"
<faizankhan666@xxxxxxxxx> wrote:

I am very new with the subject of Digital logic design and Our teacher
has given us a project of "Implementation of FIR filters" .We have to
use Verilog also.
I just know the clk,reset,set,flip flops designs....

I just want to know what filter is used for and also
Please tell me What do we mean by 4 tap filters.
What does FIR do?

Google "fir filter."

Quickie starter dose:

A signal, like a sound, can be expressed as a series of samples, each
an n-bit integer. CD music is stored this way.

A filter changes the math. A lowpass filter reduces high frequencies,
cuts the treble. If you have a stream of samples coming in, you can
store the last N of them in a list and process the list to do all
sorts of filtering.

A Finite Impulse Response (FIR) filter takes the list of recent
samples, multiplies each one by some individual factor, and sums them
to make the output.


Filter_output =

(Latest sample * Factor1) +
(1st oldest sample * Factor2) +
(2st oldest sample * Factor3) +

etc, as far as you want to go.

One simple lowpass filter is a boxcar integrator, where all the
factors are 1. The output is just the sum (or average, if you prefer)
of the last N samples.

OK, google+wikipedia will get you the gory details. Good luck.

Coffee's ready.

John

.

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