In the PowerSDR/SDR-1000 software there is a block LMS automatic notch
filter that I should have enhanced with a manual notch a long time ago
for CW in particular. That said, this operates on complex signals and
produces a complex signal. It does not hurt the image and is the single
most distortion free notch filter I've ever listened. I myself have
been caught with "analog old think" multiple times this year (such as
the AM modulation). It is understandable but as in my own cases, you
are incorrect.
Bob
KD5NWA 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.
>
>
>
--
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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