[TenTec] TenTec] SDR-1000 MDS

[Dr. Gerald N. Johnson]

On Sat, 2006-07-15 at 19:38 -0700, Lee A Crocker wrote:
> However 11 Hz is an attainable bandwidth with the
> SDR-1000, so -160 is a valid real figure and not just
> some imaginary figure.  I use 10, 25 and 50 Hz all the
> time, and I can clearly tell the difference between 10
> Hz, 25 Hz, 50 Hz, and 100 Hz.  The failure of other
> rigs to be able to attain that level of selectivity is
> notable.
> 
> Bill, thanks for the analysis I totally agree with the
> data.
> 
> 73  W9OY

With the audio DSP in my FT-857D, I don't find the DSP CW narrow filter
enhances a weak signals signal to noise. It remove QRM but doesn't bring
the signal out of the noise. The mechanical filter at the 455 KHz IF
does enhance the signal to noise ratio of a really weak signal (ten or
15 dB below the noise).

Attaining that narrow selectivity is one thing. Having it with out
ringing is another, and having it with out too much time delay to
interfere with manual tuning is yet another.


-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer