Topband: Diversity RX audio example

[Richard (Rick) Karlquist]

On 2/6/2019 9:20 PM, VE6WZ_Steve wrote:

> Using a very narrow IF can be problematic when calling CQ and having callers most of the time being off my exact QRG.  With a more open filter, and even with the EQ settings and APF, I can usually hear them. Of coarse I can also “see” them on the waterfall if they are strong enough.
> However…I will experiment a bit more with narrow IF filtering and check it out.
> 
> steve
> 

What I did in the recent CQ, SP, and ARRL 160 meter contests
is to call CQ at 350 Hz BW.  Then if a weak caller comes back,
I drop the BW to 100 Hz and use the RIT to tune him by
lining up the frequency centerline with the waterfall trail.
If someone calls outside the 350 initial BW, I can still see
him on the waterfall and get him tuned in before sending
QRZ.  It is bad practice to immediately come back to a station
way off frequency anyway because he may be calling an adjacent
station I can't hear.

On really weak stations, I try bandwidths between 50 and 100
Hz to see what works.  It's varies with the conditions.

The waterfall can easily detect stations that I have no hope
of copying.  I send those stations a QRZ to let them know that I can
see them on the waterfall and hope for QSB peak.  I can tell
from the timing of the waterfall trace that they are actually responding
to me, and not another station, etc.  A "random" waterfall trace
on my frequency usually turns out to be a station on the east
coast CQ'ing, or an east coast pileup calling an EU station, etc.

If a station is sending slowly enough, like 10 WPM, it is possible
to read the Morse off the waterfall.  It would be interesting to
see if it would be possible to copy signals farther down in the
noise this way vs audible listening.  AFAIK, there is no
"bandwidth" control on the waterfall, but it seems to be very narrow
all the time.

73
Rick N6RK