On Tue, 2008-03-18 at 21:50 +0000, ac9s@mchsi.com wrote:
>
<SNIP>
> Its direct conversion. All the selectivity is in DSP. No analog filters
> except
> maybe
> octave bandwidth front end filters.
>
> 73, Jerry, K0CQ
>
<SNIP>
>
> Thanks Jerry - Appreciate the response. Kind of smells to me like the future
> -
> less circuitry and equivalent or better performance.
>
> Keith
>
Oh, for sure, for sure. The goal of the SDR receiver maker is to have
the A/D at the antenna with enough dynamic range (conversion bits) to
handle all wanted and unwanted incoming signals with nothing analog
after than antenna connector. Though it might take an RF stage to keep
the input of the A/D from radiating. And practically required a modicum
of input filtering to keep out broad band noise like power line noise
and other out of band strong signals of less interest. Though if the A/D
has 24 bits and the most significant bit has a value of a couple volts
that might be enough dynamic range. Such an A/D has been advertised, but
I think getting one delivered this year may require giving up an arm,
leg, and first born. It will come down in price because it allows the
whole radio to be digital with the versatility that allows.
73, Jerry, K0CQ
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