[TenTec] Effect of roofing filter selection on Orion II NB

[Bill Tippett]

I wrote:

 >          Which illustrates my previous point that there is
 > nothing NR does that turning BW down manually will not do
 > (and much faster).

OE3ZK replied:

 >If that is really so, then I must have misunderstood Dough Smith's 
Article in  QEX, Jul/Aug 1998 "Signals, Samples and Stuff, A DSP 
Tutorial Part 3 - DSP Noise Reduction Methods" totally....

         What did you see that is anything but an
automatic method for building a narrow bandwidth
filter around a known center frequency?  From
page 2 under Adaptive Interference Canceller:


"In the case of a CW signal, all that's required
is a band-pass filter (BPF) centered at the
desired frequency."


...which is the same result achieved by centering
your VFO on the signal of interest, narrowing DSP
BW to reduce noise bandwidth and then adjusting
Gain to compensate for the lower noise bandwidth.
NR is simply an automatic control of what can be
done manually with the VFO, BW and Gain controls
from the front panel, except that NR does it more
slowly and indirectly.

         Some people like automatic transmissions
in their cars and some like manual transmissions,
but the net result is that the car will not go
faster because you are using a different style of
transmission.  There is no magic in DSP NR beyond
what can be done by a skilled operator using the
existing front panel controls.  To believe other-
wise is to fool ourselves into believing the "DSP
hype" some manufacturers tout in advertising (Icom
immediately comes to mind).

                                 73,  Bill  W4ZV