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Author Topic: The JT65 Digital Mode  (Read 13733 times)

WA4STO

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The JT65 Digital Mode
« on: September 13, 2012, 11:58:15 AM »
Some preppers may find the digital mode "JT65" to be of possible use in their ham radio endeavors.  Here's an example of what you could see on your computer monitor if you were using JT65:



Just above the red line, you'll see that Manuel, EA7AH from Spain has made contact with SM7MRL, Ingvarr in Sweden.

The red line indicates that WA4STO (me) is in contact with F5LNE in France.

All of the contacts shown on this screen are occurring on the 15 meter (21 mHz) ham radio band.


Newcomers and old timers alike would be quick to point out that this wouldn't be of much use to preppers!  Except ... as a learning tool.  Why a learning tool?  Well, because it makes it very clear that 15 meters doesn't seem to support radio frequency propagation to our local/regional area of interest. 

In other words, if I was in my BOL during a disaster situation and wanted to communicate and gather information from around my State, I certainly wouldn't consider 15 meters.

How about 80 meters or maybe even 40 meters?  Well, my logbook indicates that those bands would be much more useful:



This screenshot of my log shows only 40 meter (7 mHz) contacts.  Note that 40 meters seems to support propagation pretty much around the country.  Much better -- for preppers -- than, say 15 meters...

Questions? Confused?  What does any of this have to do with anything?




gil

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Re: The JT65 Digital Mode
« Reply #1 on: September 13, 2012, 01:09:47 PM »
Definitely agreed there.. 40 is great. 80m too, but the antennas must be so long! That said, I will be working on a magnetic loop soon. Three actually.. A 10ft one for 15/17/20, a 20.6ft one for 40/30/30 and maybe a 40.6ft for 40/80m. The latest one being 12ft in diameter..

My favorite band is quickly becoming 40m. After I add an SSB card to my K2, I will try the Olivia digital mode..

Gil.

WA4STO

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Olivia and OPSEC
« Reply #2 on: September 14, 2012, 10:14:54 AM »
Yes, Olivia is a superb mode.  Pity that there's so little activity.  Hey, we could fix that!

Most of the digital modes -- Olivia included -- have a bit of built-in OPSEC included, in that there are so many different flavors and speeds of Olivia.  A given group could refer to their schedule and use 16/500 one  day of the week and another speed (or frequency, or band or...) on another day. 

'course that won't keep the folks at you-know-where from getting it.  They've got brute force and unlimited budget on their side.  Not to mention a new humongous facility in Utah to store it all, until they get around to it.  Sigh..

What I'd really be interested in knowing is if Olivia can be wrapped into NBEMS so as to provide REAL error-correction.  Guess I'm a product of the early Amtor days, when every back and forth was error corrected by way of ARQ.  Then along came Forward Error Correction which I never understood.  I used FEC professionally as a ship to shore operator and never once did the ship's radio send me back a request for fills.  Just not part of the scheme, so I don't trust it. 

I recall that some of the digital modes do in fact work with NBEMS' FLARQ; just not sure if Olivia is one of them.

A neighbor is an Air Force MARS operator;  they use Olivia so it's evidently been deemed useful for traffic handling.




RadioRay

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Re: The JT65 Digital Mode
« Reply #3 on: September 14, 2012, 03:48:40 PM »
OLIVIA and CONTESTIA (similar to each other, but CONTESTIA is CAPS only and faster for the same bandwidth used) are both amazing modes as is MT63.  All of these Forward Error Correction modes (FEC) have significant improvement in readability by greatly reducing garbles, even compared to the very useful and popular PSK-31.  Digital modes also exist for 'e-mail over radio' -that is,  non-real-time , store & forward mail systems ,basically, it's an on the air bulletin board system.  TAPRN operates a WINMOR on-the-air BBS right now and it is usable from coast to coast.  The system scans pre-selected frequencies in several bands automatically, so that stations have a VERY good chance of signing in and checking mail & bulletins at any time of day, rather than waitig for the one or two times per day that a particular band might be open between them an the BBS.  Also, because there is more than one BBS, you have a choice.

The prime use for WINMOR is in the WINLINK e-mail over radio system.  This allows the sending/receiving of 'normal' e-mail to/from the internet, but you use a radio link to reach the e-mail station who is tied into the internet.  This is handy when you have localized disruption of your internet, suich as when we've had hurricanes and other dtorms that wiped-out out local internet service for a week or two.  It's good to be able to send/receive 'normal' e-mail for local emergency services and myself, to keep in touch with non-hams.

WINMOR is about as PRIVATE as ham communicatoins can be, because messaiges are compressed, then packetized. For a mortal being (non-NSA) to read this method, they would have to capture every single packet perfectly then decompress the data into it's readable form.  While not impossible, it's highly, highly unlikely.

So - Yes , digital is absolutely used in emergency comms.  As long as you can keep a computer runing along with your transceiver and etc. it's a great tool. I would HIGHLY recommend having a non-computer dependent, yet robust method to communicate (uuuuuh, Morse code) to use when the PC decides to die.
Also, the high portability of very small CW QRP rigs has much to say for them, though not for sending data files and long messages (over 50 - 100 words) unless you're really a Morse ace, but for basic communication and short SMS text type messaging, it's VERY good!

YMMV,


RadioRay ..._ ._
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

WA4STO

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Winmor
« Reply #4 on: September 14, 2012, 06:28:07 PM »
Heh, you're right, Ray; with some digital modes (like Winmor), YMMV for sure.  You might durned well get FAR better mileage!

I've been watching the Winmor group very carefully for almost a year now.  It's so reminiscent of the early Amtor BBSs, which also ran multiple freqs on multiple bands.

Me, I've been getting lousy mileage with Winmor so far.  I can connect locally to a friend, and with a message to him all set up and ready to rock 'n roll, I can't get a smidgen of transfer going.  I want, I DEMAND better mileage!  :)


RadioRay

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Re: The JT65 Digital Mode
« Reply #5 on: September 14, 2012, 07:44:34 PM »
"I want, I DEMAND better mileage!  "

You GO , Man!   ;D   For me, WINMOR has provided coast to caost transfers at good speeds.  TAPRN has a BBS in the center of the nation in Oklahoma (W0ECM-10) and it's done yeoman service for me for the many months since he put it ont he air.  I am in coastal Virginia, so it's quite a long shot, but great covaerage.  Antenna here is a 130 foot flat top 'dipol'e at 40 feet, fed with open wire line to a CHEEP MFJ antenna coupler.  The main thing that I found was to ensure that audio is not not over driven. Other than that, it's worked VERY well for me and for Buddies in a peer-to-peer (I.T. speak for ham-2-ham) use as well as servicing e-mail over radio.

Like you, I've run AMTOR and eventually, PACTOR III aboard the sailboat and from my remote cabin in Idaho for years.  WINMOR is close to that in performance.  It's not as fast and won't quite operate into the noise level as far as the hardware based PIII, BUT it's FREE, which fits my budget just  fine.

A good WINMOR to WINLINK station for you might be the W0ECM-10 on it's 7 MHZ freq (which I cannot remember off the top of my head.), but it's in the new frequency listing that is part of your WINOR/RMSexpress software.


de RadioRay ..._ ._

"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

Sunflower

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Re: The JT65 Digital Mode
« Reply #6 on: September 16, 2012, 12:57:25 PM »
Question:
If you could reach France, then so could others in your area. Maybe the contact in France could move the information needed on to you and your neighbor. Is that possible? Likely?

gil

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Re: The JT65 Digital Mode
« Reply #7 on: September 16, 2012, 02:55:01 PM »
Sure, relaying information is done all the time, often for emergency situations.

Check this out: http://www.youtube.com/watch?v=HljXA9nJc3E

Gil.

WA4STO

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Re: Relaying of messages
« Reply #8 on: September 16, 2012, 08:36:05 PM »
Tess:

That's exactly right.  And the "relay" of information is what a lot of amateurs enjoy about the hobby.  The American Radio RELAY League began for that very reason.

There are some pitfalls though, when it comes to contacting foreign amateurs.  Many countries do not allow their amateurs to participate in "third party" communications.  You are the first party, the person you're in contact with is the second; anybody else is a third party.

But... but... aren't all true 'emergency' communications allowed?  Yup.  Here in this country and everywhere that the FCC has jurisdiction.  Other countries?  Not so much...

The relaying of messages over ham radio circuits has become very very sophisticated.  For some years now, we've had automated "bulletin board" style systems up and running that you can connect to, send your messages, and expect them to get relayed along the chain.  Really slick for RV'ers, mariners and those that are just plain not "connected" in the internet sense.

73 from WA4STO



KC9TNH

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Re: Olivia and OPSEC
« Reply #9 on: September 28, 2012, 09:45:37 AM »
'course that won't keep the folks at you-know-where from getting it.  They've got brute force and unlimited budget on their side.  Not to ention a new humongous facility in Utah to store it all, until they get around to it.  Sigh..
Even the "In God We Trust, All Others We Monitor" folks have priorities - and alot of irons in the fire. Big vacuum cleaners notwithstanding, you do need to rise to a pretty good level of interest to get their assets turned on you. So, don't do that.  If you do, it's too late.

I think local groups who may be of actual practical value to each other would do well to simply find out what works that they have in common and can reliably & regularly employ.  Whether it's RTTY or CB, if everyone's got it and there's agreement on its use, it's then onto the next phase.

I am remiss in my knowledge of modern digi modes (coming from someone who used to read punched paper tape when necessary that's sad). So I need to fix that delta.

WA4STO

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Re: The JT65 Digital Mode
« Reply #10 on: September 28, 2012, 12:47:35 PM »
Punched paper tape!  yee-hah.

First at NSA, then at Red Cross National HQ, then at WCC on Cape Cod (not to mention a whole bunch of model 19s and model 28s in my basement), it was 5 level paper tape all the way.

Well, cept for ANRC, where we also ran TWX machines (8 level tape) which also made it a little easier to "figure 8" it on your fingers.

Problems with chad?  Hey, we had that DECADES before Florida's asinine voting problems.  :)


KC9TNH

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Re: The JT65 Digital Mode
« Reply #11 on: September 28, 2012, 06:35:59 PM »
Well, cept for ANRC, where we also ran TWX machines (8 level tape) which also made it a little easier to "figure 8" it on your fingers.
Ha, we called it "butterflying" which is useful also to learn when young, makes lengths of para cord deploy easier when tossing wire over trees.

Problems with chad?  Hey, we had that DECADES before Florida's asinine voting problems.  :)
Now THAT's funny. (and so true, and don't lounge back and accidentally kick the chad bucket under the TTY by accident - what a mess & where's that broom...?)
OK, turning FOG switch off now.

KC9TNH

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Re: Olivia and OPSEC
« Reply #12 on: October 03, 2012, 03:57:04 PM »
I am remiss in my knowledge of modern digi modes (coming from someone who used to read punched paper tape when necessary that's sad). So I need to fix that delta.
I am toast. I've decided to investigate digital stuff in my non-existent spare time. Like many I started trying to geek-solve the thing by looking at hardware solutions, which I've often lamented is bass-ackwards. So I dunno.  I have to learn my modes vs. methods vs. what supports what. Not that long ago if someone had said "JT65" I'd have said that must be some model of a Pratt & Whitney turbine.

I have some tutorials to take home & curl up with so it'll be awhile 'cause I don't know Contestia from Olympia from PACTOR (except that it seems that PACTOR-II & III still have some proprietary issues hanging that prevent open app development for them, go capitalistas).  From listening on MMSN I know that PACTOR seems to be a popular take-on-vacation email-like capability for mariners. Lots to learn.

I did note that there is a really small Plug & Play version of an interface from West Mountain who make the Rigblaster line; appealing due both its size and use of common data interface to both the base 450D and my 817ND. The existing 817 setup, a laptop and something that small would have to weighed against some other really quantifiable benefit to a mode not supported that required a bigger piece of gear. So I need to do some research, asking myself not the question of "what's neat?" but more like "what is it I'd like to be able to do and how much more junk must I haul around?"

Whatever it's gotta be lighter than the attached pic.

I'm still hearing that old TT-76 going chukkachukkachukkachukkachukkachukkachukkachukkachukka.....
Anyway, back to the homework.
« Last Edit: October 03, 2012, 03:59:25 PM by KC9TNH »

WA4STO

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Re: The JT65 Digital Mode
« Reply #13 on: October 03, 2012, 05:27:53 PM »
It's (hopefully) somewhat encouraging to note that the mariners (and full-time RVers for that matter) are seemingly flocking to Winmor these days, rather than the uber-expensive PACTOR that you mentioned.

Also encouraging is that, unless I've read the whole scene badly, the networks have stopped requiring (if they even ever did) that PACTOR be used.  Instead, since Winmor is free, well, hams are reaping the rewards of that, certainly.

I've had several West Mountain Radio interfaces but a couple years ago, I went with a Signalink USB interface and will never look back.  The SL offers ready-made cables for any fairly modern radio, and includes its own integrated sound card.  It appears to be about 3 inches high by maybe four inches across and maybe five inches deep.  A little sucker with huge capabilities.

73 de WA4STO



KC9TNH

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Re: The JT65 Digital Mode
« Reply #14 on: October 03, 2012, 07:03:08 PM »
I've had several West Mountain Radio interfaces but a couple years ago, I went with a Signalink USB interface and will never look back.  The SL offers ready-made cables for any fairly modern radio, and includes its own integrated sound card.  It appears to be about 3 inches high by maybe four inches across and maybe five inches deep.  A little sucker with huge capabilities.

73 de WA4STO[/color]
1.6" x 3.2" x 3.6"
Thanks for the lead; I'd looked them over, got the manual & did some comparisons apples v. apples (insofar as my limited knowledge).  Once up & running they do seem to have the edge in terms of modes. Like the other, the data cable selected for my Yaesu's will work with either.

I would imagine, based on your read, that's a good thing for EMCOMM communities trying to get the amateur players to not be requiring something for which the operator has to pony up on, or the limited budget of a group or club, ditto.

Much to learn, thanks.

Radio Preppers

Re: The JT65 Digital Mode
« Reply #14 on: October 03, 2012, 07:03:08 PM »