Electronics > RF, Microwave, Ham Radio

dumb question about JT-65

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djacobow:
So, I'm pretty new to amateur radio and have been having fun learning the ropes. I've been experimenting with JT65 and I have a question that is a bit provocative, but I hope won't stir up any anger.

Thing is, it really only works if the stations communicating have very accurately -- like sub-second -- synced clocks. Which is all well and good, except that the practical ways to achieve such synchronization (NTP, GPS, whatever) all involved communications with a third party -- in a sense, an out-of-band signal.

So, my question is, isn't that sort of cheating? I mean, is a JT-65 contact really a contact at all?

I understand that lots of contacts benefit from some kind of advance coordination (ie, "the net is on Friday's at 9am" or "I'll be operating from <small_island_nation> from <date> to <date>) but that seems qualitatively different than JT65, which, at least for me, does not work unless I sync my computer's clock pretty much right before use.

AF6LJ:
When you consider the role the Internet plays in other amateur radio activities such as DX'ing with the DX spotting sites and such, D-Star, C-4 Internet enabled communications and Winlink You could make the argument that JT-65 is much less on the Internet than other modes...
You could do away with the Internet and other external sources at least in theory.

TheSteve:
I tend to agree there is something not quite right about it. I like to think of radio as being purely radio, no help from the internet, GPS etc.
However that is clearly not the way things are as the internet is such a part of most peoples daily lives so you may as well roll with it.

djacobow:

--- Quote from: AF6LJ on April 22, 2016, 11:46:38 pm ---When you consider the role the Internet plays in other amateur radio activities such as DX'ing with the DX spotting sites and such, D-Star, C-4 Internet enabled communications and Winlink You could make the argument that JT-65 is much less on the Internet than other modes...
You could do away with the Internet and other external sources at least in theory.

--- End quote ---

You make a good point.

I sort of wasn't even thinking of the internet-based modes that don't personally rev my engine _because_ the are internet-based. I'm still in the stage where my primary attraction to radio is the somewhat romantic notion of people communicating with nothing in between.

JT-65 does excite me, though, because it's a pretty easy way for an inexperienced op like me to make crazy DX with modest gear and antenna. But that it is tailor-made for exchanging the absolute minimum info for a contact and  this sync issue sort of take a tiny bit of the fun away. Not all the fun, though.

borjam:
I don't think it's much of a problem. And you don't really need sub second accuracy, sometimes you see people with quite a clock offset :)

Anyway, if you have a problem with NTP and the Internet (which is legitimate, although it's only depending on the Internet for time synchronization, nothing else) you can also use a GPS receiver for portable operation.

Moreover: if you have a reasonably accurate clock, how many seconds will it drift in several hours? You can set an accurate time, and, once set, disconnect from the Internet and carry on.

Remember that many JT operators run Windows, a toy operating system without a proper NTP implementation, and they must resort to third party solutions. Systems member of the Unix family, such as FreeBSD, Mac OS X or Linux can keep a good synchronization within a few milliseconds without much effort, however.

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