10 Tips for the PSK31 Digital Mode HTML version
10 Tips for the PSK31 Digital Mode
Enable your RF Attenuation and increase the
volume. This helps keep a strong signal from
wiping out the weaker ones. Attenuation will
probably be around 20 dB, but by dropping the
noise level, the signal readability improves. AGC
(auto gain control) does nothing for a weak
signal; it only levels the louder ones.
PSK31 is arguably the most popular amateur radio
digital mode. It utilized phase-shift-keying to
provide robust, narrow signal width communications,
and requires very little power to QSO the world!
Use your digital modes software, or a program
like Spectrogram, to see what your noise level is
with the radio off. This will give you an idea of
how 'clean' your soundcard is. Typically,
onboard (built-in) sound hardware (as found in
most 'mainstream' computers like Dell or HP)
does not have a signal-to-noise ratio as good as
an inexpensive (less than $50) separate
soundcard. When purchasing a soundcard, look
for something with over 100 signal-to-noise ratio
in the specifications.
Use the center of your waterfall. Testing will
show that your transmit (TX) and receive (RX)
will be strongest there. Don’t blindly use 1000Hz
tone or strictly follow the VFO ‘set it and forget it'
concept. You can easily lose 20% or more of
your power on each edge of your pass band.
Pass band centering of the signal will give the
best results of both RX and TX.
Consider dual monitors (most modern video
cards have two jacks). This allows you to have
the waterfall or spectrum display on one screen,
and your logger, text window, etc. on the other. It
makes a huge difference in speed and ease-of-
use when you don't have to swap between
screens or use smaller windows for your QSO.
There's no need to have the waterfall streaking
bright red. Set your rig's volume to a low level
(less than 25% of max) and adjust your waterfall
and soundcard levels for a good contrast. Do not
overdrive your soundcard! Get the background
noise and the transmit trace well defined and
separate. Keep in mind, how your waterfall looks
does not impact decoding, but it is harder to work
it if you can’t see it.
Keep your ALC reading during transmit to as
close to zero as possible. This will keep your
signal clean and your IMD at a good level (-20s
or better is ideal). Your power output will drop,
but there's no need to 'smoke' the transmit level.
PSK31 is about an 80% duty cycle. Even with a
full duty cycle rig, it still needs to dissipate heat!
Besides, 20 watts more makes little difference.
Output of around 50W is enough to work the
world, and your fellow CQs will appreciate the
courtesy. Also be sure your voice processor is
NOT enabling when using digital modes.
Use UPPER CASE characters sparingly. Lower
case text in PSK31 varicode transmits fewer bits
of data, thus you'll increase transmit speed and
improve the likelihood of proper decoding on the
other end. For example, the difference of a
lowercase e and an uppercase E is five times
more bits! (e=11 vs. E=1101101101)
Ask for an RSQ (readability, strength, quality)
report! When in a QSO, send just a tone and ask
for your IMD and a report on how your trace
looks. This will give you a better idea of