Month: October 2014

So you want to work VK and JA on 10w ?

One answer is to to learn a low powered digital mode, CW fits the bill but things have moved on in the last 100 years and computers have provided an even better, more robust form of digital communication.

What am I talking about? No not the internet, but low power digital modes like JT65, JT9, Olivia, PSK to name a few… In this article we was going to concentrate on JT65 and JT9, like many modes its hard to know where to start, what software and what frequency should you listen to.

So what is JT65
Its a low power digital mode invented by Joe Taylor K1JT in his original paper and I quote “It is easy to show, however, that neither the encoding nor the modulation of CW is optimum. When every dB of signal-to-noise ratio counts, as it does in amateur meteor-scatter and EME contacts, there are very good reasons to explore other options. Personal computers equipped with sound cards provide a golden opportunity for experimenting with the wide range of possibilities.”

The JT65 protocol uses 65-tone frequency shift keying with constant-amplitude waveforms and no phase discontinuities. The original mode was optimised for EME QSO, but later versions JT65A, B and C had a more HF focus. The mode used in the programs we will look at is JT65A although its usually described as just JT65.

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© 2015 Dave, M0TAZ