----- Original Message -----
From: "Jeff Steinkamp" <[EMAIL PROTECTED]>
To: "Jim's mail" <[EMAIL PROTECTED]>
Sent: Wednesday, December 19, 2007 1:44 AM
Subject: Re: [Pskten] PSK Signals
No Problem. forward away. I als0 have a few discussions on my web site
about properly setting your transmiter and a discussion about IMD.
http://www.n7yg.net
Jeff N7YG
----- Original Message -----
From: "Jim's mail" <[EMAIL PROTECTED]>
To: "Jeff Steinkamp" <[EMAIL PROTECTED]>
Sent: Tuesday, December 18, 2007 15:21
Subject: Re: [Pskten] PSK Signals
Jeff,
This information sound really good. There is currently a discussion
on
another reflector I read on the topic of PSK and some of the settings
that
should be used for better signals. Would you mind if I forwarded your
message to that group?
73,
Jim Good KD5VXH
----- Original Message -----
From: "Jeff Steinkamp" <[EMAIL PROTECTED]>
To: "PSK TenMeters" <[EMAIL PROTECTED]>; "PropNet Online"
<[EMAIL PROTECTED]>
Sent: Tuesday, December 18, 2007 2:44 PM
Subject: [Pskten] PSK Signals
In the few days I've had the 30 meter antenna up, I have been able to
spend some time watching the capture of signals in PropnetPSK (PNP).
There
has been some discussion in the past about PNP not acquiring a signal
that
was quite strong. This discussion will also apply to YGPSK and just
about
every other PSK decoder that uses the PSKCORE.DLL as the Decoding
element.
PNP and the PSKCORE.DLL are quite finicky on signal quality and over
the
past few days I have observed a number of really terrible signals,
either
because they are completely overdriven or due to atmospheric
conditions.
If you look at a good PSK signal in the spectrum display instead of
the
waterfall and spread the display out, you will notice that a good PSK
signal has two signal peaks, approximately 31 Hz apart with a small
valley
in the center. A good signal lock-on will occur when the frequency
line
is between these two signal peaks. Any third order harmonic
distortion
will be reduced by at least 60db.
If the signal is overdriven, these third order products will be above
the
60 db attenuation and this is where problem can start. If you look
very
closely at an overdriven signal, you will see a mirror of the signal
in
the third order distortion product on either side of the main signal.
There will be 2 smaller peaks along with a valley. If this portion
of
the PSK signal is above the ambient noise floor, then the weak signal
properties of PSK will lock on to this signal and start decoding
because
it thinks it is a qualified PSK signal. Depending on the quality of
the
signal, it may or may not produce intelligence.
This is why it is imperative that we make sure our transmitters are
correctly adjusted for a good quality signal; rig power at something
less
than the 100% duty cycle rating of the radio and absolutely no ALC
showing
on the meter. The last test will be to have someone locally have a
listen
to the signal for quality. There are a couple of commercial 'PSK
Meters'
on the marker that will actually sample your transmitted signal and
automatically adjust the sound card gain to keep you signal clean and
pure. I do not have one of these and therefore do not have any first
hand
knowledge of these devices, but from the reports I have read, this
might
be a very good addition to the shack for PSK or other sound card
digital
modes.
Jeff Steinkamp - N7YG
Tucson, AZ
SCUD Missile Coordinates
N32-13-55.01 W110-50-51.91
http://n7yg.net
http://home.earthlink.net/~jksteinkamp
Linux User #420428
Skype : jeff_steinkamp
Yahoo Messenger: n7yg
_______________________________________________________
'I'm not the one that misplaced the Deltivid asteroid belt!' - Q
_______________________________________________
Pskten mailing list
[EMAIL PROTECTED]
http://www.nwlaweb.net/mailman/listinfo/pskten
_______________________________________________
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
