Also be aware that you're also seeing FFT effect where a strong signal looks
"sloppy" due to the color coding as the FFT frequencies are not perfect.There's
always FFT frequency spreading but you just don't see it as it's usually closer
to the noise floor.
Here's an example of a loopback test on my system
A 17dB signal looks horrible but it's actually clean as a whistle (quite
literally). Remember this a log scale so high points get "smooshed" down. If
it was linear it would look a LOT cleaner.
Here's what the wave form above looks like...as you can see...a virtually
perfect wave with no noise or artifacts.
But the FFT doesn't look so pretty...just one of the pitfalls of discrete
Fourier Transforms.Your analog ear hears the perfect tones...the DFFT has a
discrete ear so can't do that and has to add a bunch of frequencies together to
represent the signal.
-----------------------------------
Michael D. Black
From: George J Molnar <geo...@molnar.com>
To: WSJT software development <wsjt-devel@lists.sourceforge.net>
Sent: Tuesday, July 11, 2017 3:03 PM
Subject: [wsjt-devel] Apparent Distorted Signals
Drifting a little from the “extra 3 bits” conversation, folks noticing “dirty”
signals in the waterfall should not jump to the conclusion that it is the
transmitter’s fault.
Between propagation conditions, multipath, and a zillion permutations of AGC,
NB, and filter settings, the fact is that the WSJTX waterfall is not a
reliable display of transmitted waveforms. Most signals that appear dirty are
really not. I’m lucky with my Flex panadapter - one can compare both
waterfalls, one at the RF sampling level, and the other at audio. Most signals
are quite good in quality. Browbeating other operators probably isn't a good
use of our technology.
George J Molnar, KF2T Nevada, USA
On Jul 11, 2017, at 12:46 PM, Black Michael via wsjt-devel
<wsjt-devel@lists.sourceforge.net> wrote:
If you want to see what your signal looks like use hamspots.net to see who is
receiving your signal. This will indicate if they are using JTAlert.You can
then search for their callsign on hamspots.net to see if they are
transmitting...which would mean they are sitting at their rig.
Then use JTAlert's message capability via F5 to enter their callsign and send
them a message. You can also try emailing them but the JTAlert message is a
touch faster. Remember with the JTAlert message facility you can only send
about 3 messages per minute as it only transmits at 5, 20, and 35 seconds into
the minute and any new message will overwrite an older one still queued.
de Mike W9MDB
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