speedier counterparts. The Mercury project on the HPSDR yahoo group
is working on using a high speed (120 MHz) 16 bit A/D with a
band-pass filter and use the FPGA to shift and limit the spectrum,
sending a piece of the spectrum over to the PC via a USB interface.
They can be incredibly fast, I read an article where they used a
Spartan 3 FPGA to do a 2048 point floating point FFT in less than
4uSec, now that is fast.
At 08:31 AM 4/27/2006, you wrote:
>--- In [email protected], Robert McGwier <[EMAIL PROTECTED]> wrote:
> >
> > Almost right. If I bandpass filter (some at least) and if I do 1
> > bit sampling at 100 MHz and the signal of interest is 20 kHz wide
> > and I filter and downsample and filter and downsample, etc. in a
> > cascaded fashion as in cascaded-integrator-comb or half-band
> > filtering, then I can arrange a very large dynamic range.
> > Not the full 70 dB theoretical from downsampling and filtering
> > 100 MHz to 20 kHz, but the principle is clear.
> >
> > Bob
> >
>Bob,
>
> yes, right, but which DSP core of today is able to filter (before
>decimation) at 100 MHz sampling rate ? May be my knowledge of what
>hardware is available is a bit obsolete, but, AFAIK, that is beyond
>the capabilities of today's DSP hardware.
>And in any case 70 dB (70 or 74 ?) of dynamic range aren't enough to
>classify an Rx as not even near to the state of the art...
>
>73 Alberto I2PHD
>
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>
>
Cecil Bayona
KD5NWA
www.qrpradio.com
I fail to see why doing the same thing over and over and getting the
same results every time is insanity: I've almost proved it isn't;
only a few more tests now and I'm sure results will differ this time ...
[Non-text portions of this message have been removed]
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