--- In [email protected], KD5NWA <[EMAIL PROTECTED]> wrote:
>
> I and Q signals depend on their phase relationship in order for it to
> work correctly, something like a notch filter will mess up that
> relationship and render them useless. Besides the main point of a QSD
> receiver is for the CPU to do the filtering, which it can do 10X
> better than any discrete filter can. Keep the hardware simple, do the
> complex in the CPU.
>
>
Totally concur. With simple but solid front-end hardware all the bells
and whistles can be realized in software at zero additional hardware cost.
As Cecil and Alberto have recently re-iterated, all the filtering (and
demodulation) normally done by traditional hardware circuits in
traditional radios are now done in a relatively small amount of DSP
code is SDR systems. The DSP functions can have performances that
hardware solutions could only dream of attaining.
When dealing with SDR you need to think about the functions you want
to implement in your receiver or transmitter in a whole new way.
Once you are downstream from the front-end put your L's and C's and
opamps back into storage and dust off the compiler!
-Ray WB6TPU
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