Okay, so it’s probably the first JT65 contact I’ve had in more than a few years, but it’s definitely the first of this year.
I headed out this evening – a little later on than planned – to Mt Tolmie, put the 20m vertical on the roof of the truck and tuned the TS480 to 14.070, hoping to make some PSK contacts. Disappointingly, however, there was nothing to be heard. After listening around some of the other bands, I went back to 20m and listened up on 14.076, and heard the unmistakable sound of JT65.
As luck would have it, just last week I’d reinstalled wsjtx on the netbook that I use for radio, so given the lack of anything else to do fired it up and let it decode for a while. After some minor tweaking – namely correcting the time on the netbook, as JT65 is sensitive to incorrect clock settings – I saw a bunch of CQs decoded, including some from Australia and New Zealand.
Figuring that I may as well give it a try, I replied to one of them – VK4NJR in Queensland. Straight away they replied, giving me a signal report. I sent mine back, received the customary “73“, and into the log it went. It’s not every day you make a 12,000km QSO quite so easily.
If you’re not familiar with JT65, it’s a mode designed for low power and/or high noise situations. It’s a digital mode, using FSK (frequency-shift keying) to convey information. Because it can decode messages that are inaudible to the human ear, it relies on accurate clocks (at least to a few seconds) to make sure that each transmission starts at the beginning of a minute. Each transmission lasts for nearly the full minute, and in that time transmits a maximum of only 13 characters, which should give you an idea of how robust this mode is designed to be.
JT65 is part of a larger suite of modes developed by Joe Taylor K1JT, designed for weak-signal communication and for some of the more exotic methods of communication such as meteor scatter. For me, making a contact over such a long distance and with low power (in today’s case, around 5-10W) makes the whole thing a lot more fun.
Finally, there’s a really useful website if you’re working with JT65 called PSK Automatic Propagation Reporter. As the name suggests, it’s primarily aimed at collecting automated reports from people using PSK, but it’s also used for other modes – JT65 being one of them. It’s useful to be able to see where you’re being heard (or not, as the case may be) and I usually have it open somewhere while I’m on the radio.