That may be the case.
Then again, a s9+20 300 hz away from a s2 is going to have more in-band
signal content on top of the s2 - at least enough to wipe that signal out.
Now maybe that +20 is super clean and crisp but I don't find that to the
normal case.
73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie
-----Original Message-----
From: Jim W7RY
Sent: Thursday, January 10, 2013 9:03 AM
To: RTTY Mailing List
Subject: Re: [RTTY] RTTY spectrum analysis article
I disagree Jeff. If an S2 signal you are trying to receive is 300 or 400 Hz
away from a S9+20 signal, the radios AGC will not allow you to receive the
week signal. Filters in the radio are essential!
73
Jim W7RY
-----Original Message-----
From: Jeff Blaine
Sent: Thursday, January 10, 2013 6:34 AM
To: Al Kozakiewicz ; RTTY Mailing List
Subject: Re: [RTTY] RTTY spectrum analysis article
The best place for RTTY rx filtering is in the demod, not the rig. narrow
crystal filter and it's group delay gives more problems than it solves.
The solution is to run a filter wide enough to let you quickly tune (400-500
hz?), but not so razor sharp that the rig rather than the demod is doing the
selectivity filtering.
73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie
-----Original Message-----
From: Al Kozakiewicz
Sent: Thursday, January 10, 2013 8:30 AM
To: RTTY Mailing List
Subject: Re: [RTTY] RTTY spectrum analysis article
No, this doesn't necessarily mean you should give
up "true" FSK keying. There are things you can do about it, and some
people are people taking responsibility and doing these things--please read
the
article!
That was depressing. Transmit filters are only enabled on the Icom radios I
have on SSB, so there is no apparent option for improvement that I can see
for without switching to AFSK which, in turn, makes the radios just about
useless for contesting as there is no practical way to use the RTTY Rx
filters without also transmitting FSK.
Unless I missed it in the article, I see no way to improve things short of
buying a new radio with a design that does not currently exist!
Al
AB2ZY
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