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eHam Forums => Digital => Topic started by: W1CEW on February 24, 2013, 06:08:34 PM



Title: What digital mode is this?
Post by: W1CEW on February 24, 2013, 06:08:34 PM
The audio is a little low, feel free to adjust:
https://www.youtube.com/watch?v=jwd9DmN8Cxs

Sorry for the "NOOB" question.  I've been trying to identify this digital mode, I know it isn't Olivia, some kind of FSK.  MT63?  It's been quite active all day in this area of 40 meters.

Thanks for any info!

73,

Chuck
W1CEW


Title: RE: What digital mode is this?
Post by: K2JK on February 24, 2013, 07:39:22 PM
That's JT65 running on 7076 USB.


Title: RE: What digital mode is this?
Post by: W1CEW on February 25, 2013, 03:32:48 AM
Terrific.  Thanks!


Title: RE: What digital mode is this?
Post by: VE3FMC on February 25, 2013, 04:37:39 PM
Yes, JT65 but he is operating on the wrong sideband. We use 7.076 USB.


Title: RE: What digital mode is this?
Post by: W1CEW on February 25, 2013, 05:37:41 PM
That's just my own ignorance, when I recorded the video.  I'm looking into the software though to check it out. Looks like a fun mode to get into.


Title: RE: What digital mode is this?
Post by: WD4ELG on February 25, 2013, 09:16:20 PM
It is fun, to see what low power and minimal antennas can accomplish.  Just don't look for any ragchewing to go on with it.

Get the free software JT65-HF.

Here are some good articles:

http://nw7us.us/jt65a.html

http://www.4x4ham.com/content.php?205-Work-the-World-on-10W-An-Introduction-to-JT65A

http://ve3bux.com/files/JT65_Operator_Guide.pdf

http://www.eham.net/ehamforum/smf/index.php?topic=82553.0



Title: RE: What digital mode is this?
Post by: VE3FMC on February 26, 2013, 07:01:41 AM
That's just my own ignorance, when I recorded the video.  I'm looking into the software though to check it out. Looks like a fun mode to get into.

I have over 2000 contacts using JT65. It is a great mode for working DX, WAS etc. One thing is very important when it comes to decoding JT65.

Your computer clock must be dead on. To sync the clock download Dimension 4. Set it up to sync the computer clock with one of the US Government time servers. I sync my CPU clock every 2 minutes.

I will be watching the waterfall for your call.


Title: RE: What digital mode is this?
Post by: W1CEW on February 26, 2013, 07:11:09 AM
I got the software last night and monitored a bit.  What's amazing is how many calls I could see, even though it didn't appear to the ear to be that many actually on frequency.  What's the reasoning why the clock sync needs to be so perfect?  Just curious.


Title: RE: What digital mode is this?
Post by: VE3FMC on February 26, 2013, 04:53:06 PM
I got the software last night and monitored a bit.  What's amazing is how many calls I could see, even though it didn't appear to the ear to be that many actually on frequency.  What's the reasoning why the clock sync needs to be so perfect?  Just curious.


If the CPU clock is not synced eventually the software will stop decoding. It may take a day but it will. Happened to me until I installed Dimension 4.

You will decode signals that you do not see on the waterfall. I have worked stations on 12 meters and could not hear any audio or see any trace on the waterfall. But the software knew the signal was there!

BTW I use a SignaLink USB for my interface between my FT-950 and computer. That interface has been connected to 4 different HF rigs since Sept 2007 and has never failed me.



Title: RE: What digital mode is this?
Post by: KG6AF on February 26, 2013, 06:23:35 PM
I got the software last night and monitored a bit.  What's amazing is how many calls I could see, even though it didn't appear to the ear to be that many actually on frequency.  What's the reasoning why the clock sync needs to be so perfect?  Just curious.


JT65A operates on a 1-minute cycle.  Stations start transmitting at 1 second after the top of the minute, then stop at 48 seconds.  This leaves a 13-second deadtime in which receivers can decode what was heard.  Then the cycle repeats.  If you're too far out of sync, you miss part of what the other stations are transmitting, or they miss part of what you're transmitting.

I've found that you can be off by as much as a couple of seconds, but it's a good idea to be closer than that.  If you're using JT-65HF, look at the times under the DT (delta time) column.  If you see some that are - (transmitted early) and some that are + (transmitted late), you're probably in good shape.  If all of the times you see are the same sign (and more than a few tenths of a second), it's time to check your clock.  The horizontal red lines drawn across the waterfall also serve as a quick and easy time sync check.

I've found that Dimension4 does a good job of keeping your PC clock accurate.


Title: RE: What digital mode is this?
Post by: WB0FDJ on February 27, 2013, 11:39:22 AM
W1CEW

You might wish to check out the WSJT website (sorry I haven't got the link handy, it's googable). There Joe Taylor, K1JT has a lot of information about the many different modes available through his WSJT software suite. He is the original developer of the JT65 software.  I use his software on my linux boxes, built from source code. Thats also where you'll find the WSPR software. When running my windoze box I use the JT65-HF for ease of use but still harbor the notion that I may wish to try some of the other modes in the future so I try to keep his stuff up to date.

Welcome to JT65A.

Doc WB0FDJ


Title: RE: What digital mode is this?
Post by: W1CEW on February 27, 2013, 12:09:00 PM
Thanks, Doc!  I'm running windoze, though of course I have a great affinity for Linux (I'm a web developer).  I run HRD logging when running other modes and I guess I'd be stuck doing "double entry" for my logging activities, though I guess it isn't that much of a hassle.  I did make a few contacts last night, though not really using a great rig interface.  I just ran an output line from my laptop to my W2IHY EQ box input and put the rig on VOX.  Seemed to work.  The http://pskreporter.info/pskmap.html PSK reporter map had me all over the place, which was really very cool.  Excited about this mode, it seems like lots of fun.


Title: RE: What digital mode is this?
Post by: AJ4WC on February 27, 2013, 01:56:02 PM
I don't think it's necessary to update the clock that often.   I have my computer set up to update about every 15 minutes, which is way more than necessary.  Watch your Delta Time and make sure it's within 3 or 4 seconds.  I can go an entire day or two without synchronizing before it gets that far off.  About once a month, I setup in an ALT QTH without Internet and I can do JT-65 for a day or so before the clock gets off by 3 to 4 seconds.  But, I also discovered that you can adjust the clock manually using the Offset to compensate.  On a long weekend, I've had people tell me that my clock is off, but it didn't stop us from having a successful QSO, so it obviously wasn't an issue, right?


Title: RE: What digital mode is this?
Post by: AH6RR on February 27, 2013, 02:47:29 PM
Thanks, Doc!  I'm running windoze, though of course I have a great affinity for Linux (I'm a web developer).  I run HRD logging when running other modes and I guess I'd be stuck doing "double entry" for my logging activities, though I guess it isn't that much of a hassle.  I did make a few contacts last night, though not really using a great rig interface.  I just ran an output line from my laptop to my W2IHY EQ box input and put the rig on VOX.  Seemed to work.  The http://pskreporter.info/pskmap.html PSK reporter map had me all over the place, which was really very cool.  Excited about this mode, it seems like lots of fun.
JT65HF can be run through HRD for the frequency control and PTT ect. and JT Alert can be setup to send the contacts to the log with out doing the export/import thing. I have made over 400 contacts using JT65HF and do find it fun dut it is not for doing a lot of them fast by any means. It is fun to rup QRP levels and work the world. WSPR is another one but it is more a Beacon mode than anything I was able to copy a station in Zimbabwe who was using 250mW and since there is a realtime reporting like PSK Reporter they sent me a card and awe exchanged a couple of emails about our setups it was way cool. Zimbabwe is almost exactly 1/2 way around the world from Hawaii. I was using a 3 element SteppIR and a TS-850 at the time.Have fun on JT65 who knows you might see me on the waterfall one of these days.

73
Roland AH6RR


Title: RE: What digital mode is this?
Post by: W1CEW on March 18, 2013, 01:35:27 PM
Just following up -- I've been playing with this mode quite a bit now.  It can be a little addicting, I think.  On the downside, there's zero personal information exchanged.  I mean zero, unless you can squeeze your life story into 13 characters, ha!  I've filled the gap by sending an occasional post-QSO email.

On the plus side, it seems very efficient, though time consuming, and affords the ability to connect around the world with a pretty humble set up. Also it's possible to set up remote desktop on your rig PC and monitor or QSO from any room from the house... OR maybe even from work (?).  :-)

73,

Chuck


Title: RE: What digital mode is this?
Post by: VE3FMC on March 18, 2013, 05:15:49 PM
I operate JT65 on one computer while surfing the net on another computer. Both monitors are side by side.

You are correct, it is not a rag chewing mode. But it was never meant to be.

Addictive? Uhhhh maybe just a little (1700 logged contacts and counting) Great way to work some DX, or WAS (have that one already)

Sure you can operate remotely. I used to work a guy on Olivia quite often. He lived in an apartment in NYC, and his station was on Long Island at his home he had there. The experts on remote operation will weigh in here. I have done it a few times before my old laptop crashed. But only digital, not voice.

So others will help you out with the remote side of things.

We have not worked each yet but I am sure we will in the future. 40 M would be the band for us to work each other on.

73 Rick VE3FMC


Title: RE: What digital mode is this?
Post by: W1CEW on March 22, 2013, 04:04:49 PM
Ha, just saw you on 15m!  :)


Title: RE: What digital mode is this?
Post by: VE3FMC on March 22, 2013, 05:09:15 PM
Ha, just saw you on 15m!  :)

You should have called me. I am on 7.076 at the present time.