Looking back in my logbook I see on the 12 July 1997 that I made a transmission on 73kHz that was received by G3PLX 393km away in a bandwidth of a few tens of milli-Hz. Peter was using the new fangled DSP stuff in a Motorola DSP card, to display the narrowband filtered signal on a waterfall display.
I was radiating perhaps 5 - 10 milliwatts ERP (from a 200W transmitter)
No information was exchanged that day, just confirmation of the carrier being switched on or off using the telephone as a back link. Peter suggested I write some software to generate very slow CW to key the transmitter and send it to him.
On 27 July He received the first SLOWCW signal from me with positive ID of the callsign, sent according to my logbook notes with 100s dots between 0400 to 0718 UTC. We then did the same again for several nights running, varying the dot speed . This completely smashed the one-way distance record for the 73kHz band. There were several at the time who said "its not real amateur radio, it's computers talking" but those voices were soon silenced.
Others wrote software to generate the keying and suddenly everyone started using SLOWCW which for some unfathomable reason started to be called QRSS (why ?)
Now 20 years later, it still seems to be widely used, albeit with a few variations like DFCW to speed up exchanges.
Andy G4JNT
UPD - Справедливости ради, отмечу, что QRSS использоался и
гораздо ранее, еще в начале XX столетия!
А так же, в эпоху еще до Радио: первая проводная трансатлантическая телеграфная линия между Англией и Северной Америкой использовала автоматическое оборудование для передачи и приема сообщений и скорость передачи составляла несколько символов в час!
