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
i2phd wrote:
> --- In [email protected], "jr_dakota" <[EMAIL PROTECTED]> wrote:
>
>> Rule number 1 in SDR: Anything that can be created in hardware can
>> also be created in software, including I-Q mixers and LO's
>>
>>
> Theorethically yes, but not in practice...
> The ideal scheme would be to attach an analog to digital converter to
> an antenna. The PC would read the converter, and then software would
> transform the stream of data from the converter to any other form.
>
> The ideal scheme is not practical, however, as you would need a high
> speed ADC, with the adequate number of bits of resolution. Today's
> technology doesn't offer 100 MHz, 24 *real* bits ADCs.
> So you are forced to convert the range of frequencies you are
> interested in to a more manageable value, and for this you need a
> mixer, and you need to get rid of the conversion image frequency. This
> latter step can be done exclusively in hardware, not in software. If
> you know of a way to do it in software, please tell me, I will be
> delighted to learn it.
> And if you patent it, and you sell it to the cell phones
> manufacturers, you will also become a rich man.
>
> 73 Alberto I2PHD
>
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>
> Yahoo! Groups Links
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--
AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
Laziness is the number one inspiration for ingenuity. Guilty as charged!
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