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Last updated 8June 2012 |
QRSS - Stretching the limitsQRSS is extremely slow Morse, usually machine sent. It is common to use dot-lengths of three seconds (QRSS3) for 'local' contacts around Europe, and much longer, typically 60s (QRSS60), for inter-continental working. This may seem tedious but the upside is that it allows the bandwidth to be reduced considerably, improving the signal to noise ratio, and increasing the effectiveness of your signal by tens of decibels. This mode was originally described and tested in 1997 by G3PLX who used his microprocessor-based system to communicate with G4JNT on the now-defunct 73kHz band. The 393km path was a previously unheard of distance for this frequency. The receive system displayed the signal on a computer screen so that the Morse dots and dashes could be read by eye (a spectrogram). QRSS became widely used with the advent of publicly available spectrogram software. The first program available was actually designed for birdsong but purpose-designed software such as such as Argo and Spectrum Laboratory (SpecLab) quickly followed. See my links page for downloads. I was one of the first to use QRSS, and indeed suggested this name - using the same syntax as 'QRPP' which means extremely low power. Having been a CW enthusiast for several decades, I was astonished at how this mode can produce 100% reception of signals which are totally inaudible by ear. It is also astonishingly good at producing readable signals when the QRN makes conventional CW impossible - which is frequently a problem on LF in the summer. I made the first two-way QRSS contact, with G4JNT who had been the receiving station on G3PLX's first tests, and made the first G-ON on this band. Click on the link below to see pictures of some historic and interesting contacts. A really good description of QRSS can be found at ON7YD's site. It is in English, but there are links to translations in Russian, German, Italian and Japanese. A variant of QRSS is DFCW (dual-frequency CW) which has dots and dashes the same length, but on different frequencies (see ON7YD's site). This is more complex to transmit but saves on transmission time. QRSS/DFCW reports are: 'O' = good signal; 'M' = poor but readable; 'T' = unreadable. See gallery of displays of Spectrogram plots. |
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Last updated 8June 2012 |