Re: [linrad] DSP Question

["Mark Erbaugh" <mark@xxxxxxxxxxxx>]

Oleg,

> You can design an LPF and then multiply it's taps by the
> complex sinusoid exp(j*w0*t). This will result in a two sets of
> coefficients (real and imaginary). Each set represents a BPF
> centered at w0, but the two filters will have 90 degree phase
> response difference.
>
> I use such technique in my HF DSP transceiver design.

Thanks for the reply. Sorry for the delay in getting back to you, but I
wanted to try and understand what you were saying.  All this complex math is
hard to get straight in my own mind.  My head is spinning like those complex
phasors <g>.

I think I understand what you are saying.  I assume that t represents the
sample interval and that if the number of taps in my filter is less than the
number of samples, that the complex sinusoid won't go all the way from 0 to
2 pi (all the way around), or is t based on the number of filter taps so
that the sinusoid goes from 0 to 2 pi over the number of taps?

Thanks again and 73,
Mark

LINRADDARNIL