Tips on using Digi modes
Tips for the PSK31 Digital Mode
1ST off Please
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 mode. Even with a 100 watts full duty cycle rig, it still needs to dissipate heat! Besides, 20 watts more makes little difference. I've worked VK3 and VK4 on just 35 Watts an 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 enabled when using digital modes, Also check the propagation for the band your on and the time of day, its no good putting KW's out on a closed band,
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! 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’.
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 10.140.
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!
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 levels.
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 adjust it.
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 a microphone.
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.