10 Tips for the PSK31 Digital Mode
There are hundreds of digital modes. To get
started or to learn more about the most common
ones, acquire ARRL’s ‘HF digital Handbook’ by
Steve Ford, WB8IMY. For the technical types, be
sure to snag Roland Prosch’s (DF3LZ) ‘Technical
Handbook for Radio Monitoring’.
Overdrive: Turning the volume of your radio up so
high that you risk damage to the soundcard, or cause
signal ‘splatter’. Similar to maintaining your ALC
Pass band: The range that your transceiver can
receive when on a single frequency. Typically
around 3000Hz wide.
PSK (Phase Shift Keying): A form of modulation
that shifts the transmit signal in order to carry more
information. PSK31: is a digital mode created in the
1990’s by Peter Martinez (G3PLX) that is about 31Hz
wide on your waterfall.
RF (Radio Frequency) Attenuation: A suppression
of signals received. You’ll often see a noise level
reduction, with a minor sacrifice to the desired signal
reception. Check your radio’s manual on how to
RSQ (Readability, Strength, Quality): Much like the
familiar ’RST’ reports, using a 599-type reporting
scheme. Instead of ‘Tone’ (Morse Code), use
’Quality’. 95%+ readable, with a very strong waterfall
trace, and a clean (no splatter) signal would warrant
a 599 report.
Soundcard: A piece of hardware in your computer
that produces sound, and often allows input, as with
VFO (Variable Frequency Oscillator): It’s that knob
you use to change frequencies on your radio.
Varicode: A streamlined coding system that allows
nearly whatever your computer keyboard can type to
be transmitted in shorter lengths.
Waterfall: A visual display of radio signals (and other
sounds) found on the tuned frequency.
Try 30 meters PSK31! It’s a robust band, offering
the best of 20M and 40M. It’s a small segment of
a no contesting band. Used only for digital
modes and CW. Be sure to operate within your
privileges. PSK31 can typically be found around
DEFINITIONS of TERMS USED:
AGC (Auto Gain Control): The ability to reduce
signal strength on-the-fly (fast or slow), giving you a
more level audio reception on stronger stations.
ALC (Auto Level Control): A voltage adjustment or
reading, indicating your TX signal levels . ALC is
designed to control voice and carrier signal levels,
not digital modes. Typically, if the ALC meter moves,
then the microphone gain is too high.
Signal-to-noise (S/N) ratio: A comparison of the
signal levels to the relative noise level. Ideally, a
perfect signal would have no noise, but realistically,
you’ll want a S/N ratio well within the tolerances of
the mode you’re using. PSK31 tolerates about a
10dB S/N ratio.
dB: Sound level, or ‘decibels’ are used to measure
the relative strength of a signal.
Digital Mode: A converted signal transmitted from
your radio to be ‘de-converted’ by the receiving
station. Much like a computer modem, a digital feed
is converted to analog, sent across a transmission
medium, then reconverted back to a readable signal
at the receiving station.
Duty cycle: The total time of actual transmission
levels. When your radio is transmitting, there’s an
on/off process that takes place. Transmitting at a
100% duty-cycle indicates that your are using 100%
of your radio’s power, 100% of the time. Better
radios will allow this, while others will eventually fail
under the pressure of such a load.
IMD (Intermodulation Distortion): The ratio, in dB,
used to determine the quality of your transmission.
Unwanted ‘products’ or signals reduces IMD levels.
More power does not mean better copy!
RELATED WEB LINKS:
ARRL’s ’HF Digital Handbook’,
by Steve Ford, WB8IMY
‘Technical Handbook for Radio Monitoring I’,
Roland Prosch’s (DF3LZ)
Digital Master 780, by Simon Brown, HB9DRV
Spectrogram and other software: