I am simply saying that I have not had to use such techniques or filters
since I started using PSK. I have worked 133 countries in the mode, using
my SSB filters, and have yet to have even a nearby signal block out one of
them so badly I couldnt copy it. Maybe its my TS570s, my software, my
location, etc. I dont know. All I know is that it works. Using broadband
copy, I often see 15 or 20 stations being printed out across the band at any
given time. Once in a while, someone doesnt know how to limit his power, or
how to turn it down so that he has no ALC showing on his meter, and he sends
out so many spurs that the broadband can copy him in a dozen places up and
down from his normal signal, but even that main signal isnt so strong it
disturbs other signals within just a few cycles of it. True, a narrow
filter would filter those out, as well as any other signas between them, and
make the broadband copy capability useless. It would also disallow the MixW
software to have all three of its copy channels/windows operational as
well - it doesnt have true broadband copy, but you can set all three windows
to copy anywhere across the sound cards passband.
Danny Douglas N7DC
ex WN5QMX ET2US WA5UKR ET3USA
SV0WPP VS6DD N7DC/YV5 G5CTB all
DX 2-6 years each
.
QSL LOTW-buro- direct
As courtesy I upload to eQSL but if you
use that - also pls upload to LOTW
or hard card.
moderator [EMAIL PROTECTED]
moderator http://groups.yahoo.com/group/DXandTalkK
Danny Douglas N7DC
ex WN5QMX ET2US WA5UKR ET3USA
SV0WPP VS6DD N7DC/YV5 G5CTB all
DX 2-6 years each
.
QSL LOTW-buro- direct
As courtesy I upload to eQSL but if you
use that - also pls upload to LOTW
or hard card.
moderator [EMAIL PROTECTED]
moderator http://groups.yahoo.com/group/DXandTalk
----- Original Message -----
From: "Roger J. Buffington" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, March 07, 2007 9:03 PM
Subject: Re: [digitalradio] narrow filters/PSK
> Danny Douglas wrote:
> >
> > I have a hard time visualizing the need for a narrow filter, for such
> > narrow modes. You can sit, in PSK for instance, slap up against
> > another PSK signal and still copy much weaker signals. Thats the
> > whole purpose of the narrow band digital modes to start with. I use
> > WinWarbler (now) to do my digital transmission in both PSK and RTTY,
> > and when I want to do something like Olivia or MFSK etc. I go to
> > MixW. I particularly like WinWarbler because it has the wide band
> > copy ability in PSK. I.E it will automatically copy (and show all the
> > channels) in a 2 or 3 KC bandwidth - at the same time. Using a narrow
> > filter in there would completely negate that fantistic capability.
> >
> > I have never had to use my narrow filters in order to copy a digital
> > signal, and yes I have played with them to see what difference it
> > made. Todays rigs, with their dsp filtering just seem to bypass any
> > need at all for additional filters for digital operation, though I do
> > see the need for CW filters, and have 250 and 270 cy fliters in my
> > two rigs because I use my ears, and not the computer to detect and
> > read that mode.
>
> Not meaning to be argumentative, but I believe most of the above to be
> objectively untrue from a technical standpoint. A strong adjacent PSK31
> signal inside the passband will desensitize any rig's receiver by
> activating the AGC such that if you try to receive a weaker adjacent
> signal, you will be unsuccessful. If you disable the AGC often the
> stronger signal will simply overload the receiver. IF filtering is
> essential for preventing this, and countless times filtering has made
> the difference between good copy and no copy. DSP filters are only
> helpful if they are in the IF, preventing AGC action by signals outside
> the passband. Software solutions, such as those in MixW or PSK Deluxe,
> cannot affect the rig's AGC action and are no substitute for good IF
> filtering.
>
> de Roger, W6VZV
>
>
>
>
>
> Announce your digital presence via our DX Cluster
telnet://cluster.dynalias.org
>
> Our other groups:
>
> http://groups.yahoo.com/group/dxlist/
> http://groups.yahoo.com/group/themixwgroup
> http://groups.yahoo.com/group/contesting
> http://groups.yahoo.com/group/wnyar
> http://groups.yahoo.com/group/Omnibus97
>
>
> Yahoo! Groups Links
>
>
>
>
>
> --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.446 / Virus Database: 268.18.7/713 - Release Date: 3/7/2007
9:24 AM
>
>
