[Icom] Using PBT on the IC-756 PRO 2

Thu, 18 Jul 2002 23:35:04 -0700

Larry,

If you watch the little graphic symbol at the top of the screen, or press
and hold the [FILTER] key to bring up the Filters menu, you will be able to
observe the effect on the IF passband as you rotate the inner and outer TWIN
PBT knobs. Shifting the upper flank will modify the high-frequency content
of the recovered audio; shifting the lower flank will change the
low-frequency content. This accounts for the changes in audio quality which
you observed. Turning the two knobs together is equivalent to IF Shift.

The two controls allow independent adjustment of the upper and lower flanks
of the passband. The selectable shape factors , Twin PBT and filter
bandwidth adjustments, in combination, give the operator control over the IF
passband unachievable with classical analogue filters.

For a comparison of DSP and analogue filter performance, please click the
"Passbands" icon on my Icom page.

Best 73,
Adam, VA7OJ/AB4OJ
North Vancouver, BC, Canada
http://www.qsl.net/ab4oj/
Note new e-mail address:
mailto:[email protected]

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of [email protected]
Sent: Thursday, July 18, 2002 11:46
To: [email protected]
Subject: [Icom] Using PBT on the IC-756 PRO 2

Hi to all that read this.

I have owned my pro 2 since Dec/01. Last week, during the IARU(ssb) contest,
I used(tried) the PBT and think I maybe missing something in operation or
maybe expect it do something more than it can do. Yes, any contest can be
pretty brutal for
congested bands and interfering signals close by signals so it may not be
fair to judge the PBT capabilities of the pro 2 to harshly.

I first set my pro 2 for a 2.1 bandwidth and sharp filter mode. While
listening to a station on say 14.200.00 and having another station
transmitting on 14.201.75, I thought that by using both controls together
on
the PBT and shifting to the left or right side, I could pretty much reduce
the interference from that other station(14.201.75) by shifting the
passband,
as displayed on the lcd. It seemed to me that by moving that PBT,  just
muffled the interfering station and/or increasing the pitch of the
station(s). I may not be to exact here, as it was very early in the morning
and I was quite tired. I am going to try to find 2 stations that are very
close and experiment again with the pbt controls. It won't be contest qrm,
but hopefully close enough to try. Yes, I know some of you are saying,
during
a contest, who has time to fiddle with all that, as its just work em and
move
on. I know, but wanted to see the capabilities of the pbt and I was done for
that contest.

I also tried to use one of the 2 controls on the PBT, but found that mainly
all it did was to further reduce the passband, say from 2.1 to 1.6 and of
course the narrower the pb, the less intelligable and higher pitched the
signal becomes. At least to my ears, anyway.

Thanks again to all that read and reply.

vy 73's...
Larry.. N2LH
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