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FT-847 DSP



Ed Cole wrote:

As one with severe hearing imparement, I am interested in any methods that
improve intelligibility.  I believe you have an FT-847, how do you rate the
DSP NR and DIG. FIL modes.  I use the NR on AO-40 combined with RF Gain
reduction to lower passband noise fairly successfully.  However, the DIG FIL
seems to add distortion that is counterproductive for my "tranducers"
(ears).  Yet, I regularly use DIG FIL for terrestrial weak signal ssb, and
the DSP cw FIL set to 100 Hz for eme.  Go figure.

Wayne replies:

Have you tried an audio equalizer to compensate for the frequencies where
your hearing is impaired?

For comparison purposes, here is my subjective opinion of the FT-847 DSP.

SSB DIG FIL
Excellent.  I don't notice any distortion, and I like the continuously
adjustable highpass and lowpass filters.  Together with IF shift, I use it
on HF to reduce interference from stations that are less than 2 kHz away
from the station I'm trying to hear.  I have never encountered similarly
crowded conditions on any satellite because satellites don't have contests
and selective propagation.

CW DIG FIL
Okay, but extremely stupid.  Why it doesn't provide adjustable highpass and
lowpass controls, same as in SSB mode?  It is very annoying to have a fixed
center frequency.   I think I have a hearing impairment at the fixed center
frequency of the CW DSP filters.  It's annoying to have only 3 fixed
bandwidths, and it's inconvenient to go into the menu to change the filter
bandwidth.  Thank goodness I have an INRAD 400 Hz crystal filter.

NOTCH
Awful.  I always get severe clipping-type distortion, as something is driven
to the rails.  It takes several seconds to fully notch an offending carrier.
I really miss the manually tuned IF notch filter in my old Icom 751 which
was usable even in CW mode.

NR
Awful.  I haven't found any situation where it improves intelligibility.

Wayne Estes W9AE
Beijing
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