There are a good many people having a stab at running JT65 ( http://en.wikipedia.org/wiki/JT65#JT65 )
The mode is interesting as it is much about very precise timekeeping as anything. By very carefully syncing the transmitter and receivers software the receiver can complete reception below any normal communication mode.
It sort of reminds me of when I was once asked to be part of a team watching a particular window in a particular apartment building to see if the light was on at a certain time. In the midst of all the noise (all the lights going on & off in the hundreds of windows) that one particular window would be lit up at exactly a certain instance apparently meant something – afraid we were never told exactly what, but it much have been important!
Through timing a sequencing JT65 is hundreds of “little windows” that the software checks in a certain sequence at very specific times. That binary is parsed into a 13 character message from some 47 seconds churning!
I’d originally said I wouldn’t write about JT65 until I had logged 100 JT65 QSOs. Well I am not quite there but I think my thoughts have jelled.
JT65 is a QSO distilled down to nearly the least amount of data to transfer in meeting the most basic requirements for a QSO. Remember a QSO has a certain form – exchange of reports, call signs and such – you can find more on that at: http://en.wikipedia.org/wiki/Contact_(amateur_radio)
Ragchewing is simply not going to happen in a JT65 QSO – there is so little data being moved that conversation gives way to just the contact requirements of a QSO.
So what is JT65 good for? Well it does qualify as a QSO you can log and count for awards. It does work when conditions are very sour making even CW a task. It brings a challenge of very accurate clock timekeeping to the ham shack. I’ve found it works a charm as a semi automatic QSO process when doing other shack tasks that would make many modes difficult. It is a pretty fear-free way to try digital communications.
Using JT65HF Software a QSO is pretty well defined. Call CQ, Answer CQ Call, Send Report, Acknowledge and Return Report, RR Confirm and an optional 73. Each 13 character and the wait to decode takes about 48-50 seconds, and the next person doesn’t transmit until on the start of the next minute. A full JT65HF QSO is something like a 6 minute undertaking to exchange only the basics.
Yet what other mode can I work across the USA on 160m at less than 20 watts input (and my 160m antenna is most certainly a negative gain antenna) in awful conditions? Even interesting modes like Throb and Olivia are surpassed for rough condition basic QSO contacts by JT65HF.
Do I “like” JT65HF? When conditions are tough it does meet my needs to just reach out and confirm that I can make a contact. While it doesn’t warm up to my interest to learn about my fellow ham, understand his “operating conditions” and hopefully leave a favorable & friendly impression, it does work when almost nothing else does.
I’m impressed by the technology and cleverness of the mode.
It is also nice to have a communication alternative that is sort of mindlessly “point-and-shoot” and nearing QRP levels.
It is obvious the capabilities of JT65 have kept it alive on terrestrial HF bands for several years now. While it never will displace full conversational digital modes, it is neat and has its place.
I can see having the software on the machine and running some periodically. By the way, you get the JT65HF version of a pile-up as a Wisconsin Station on 160m. Apparently not too many fellow Packer Fans run JT65HF regularly. Here is a manual for JT65HF http://openhpsdr.org/wiki/images/0/0c/Jt65-hf-setup.pdf
Catch you on the air, broadcasting exactly on the top on the minute in JT65HF!!
All best and 73