JT65a

A MINIMALIST’S ERROR FREE HAM RADIO PROTOCOL

OVH - July 2013 -- by Terry WA5NTI 1

WELCOME TO THE WONDERFUL WORLD OF

JT65-HF

JT65-HF is a amateur radio digital mode written by W6CQZ. It is an extremely efficient weak-signal mode – it is possible to decode signals you simply cannot hear with your ears in audio and can barely see on your waterfall display.

JT65-HF is so labeled because it sends 65 discrete audio tones, spread out over 175Hz of bandwidth. The “JT” part comes from the original creator’s name, Joe Taylor (K1JT) - the 1993 winner of the Nobel Prize in Physics, and the author of the excellent HSMS and EME software known as WSJT.

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FOR FURTHER, MORE IN-DEPTH, STUDY THE FOLLOWING INTERNET LINKS SHOULD HELP

Download

JT65-HF

: http://iz4czl.ucoz.com/index/0-28

JT-Alert

add-on software with visual and audio alerts http://ham-apps.com/

SP time sync

(lets you synchronize your computer's clock with any Internet atomic clock (time server) http://www.spdialer.com/ ------------------------------------------------------------------------------------------- http://hamspots.net/wsjt/ "cluster"-type spots for JT65-HF and other digital modes http://groups.google.com/group/jt65-hf JT65-HF group discussions (on Google groups) http://www.meinberg.de/english/sw/ntp.htm Meinberg time sync OVH - July 2013 -- by Terry WA5NTI 3

JT65 is a tightly structured protocol with a severely limited set of structured messages and a limited 'free text' message type limited to 13 characters in length.

In any one minute period you may send any one of the structured message types, 13 characters of text or any one of the 3 shorthand messages.

Nothing more, nothing less !

JT65 is not a free form data transmission protocol like most other modes we use.

Each transmitted 'frame' is of a fixed length, starting and ending at a predefined time.

By using this restrictive timing arrangement and a fixed frame length it becomes possible to achieve some “signal gain” by knowing when and where to look for signals.

A properly executed QSO takes

exactly

complete.

six (6) minutes to OVH - July 2013 -- by Terry WA5NTI 4

Transmissions begin at precisely

1 second into a new minute

and end precisely 46.811 seconds later. A transmitted message (frame) will convey

72

bits of user information with an additional

306

bits of error correction data (FEC) for a total of 378 bits.

That’s more FEC data

being transmitted in each frame

than it is user payload data

!

Its timing, modulation method and heavy FEC that allows it to work so well at very low signal levels.

Within that frame of data 72 data bits you may have any one of the set of structured messages, a 13 character free form text message, or any one of the 3 shorthand messages.

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The six (6) Structured messages

are as follows.

1) CQ CALLSIGN GRID 2) CALLSIGN CALLSIGN GRID 3) CALLSIGN CALLSIGN -## 4) CALLSIGN CALLSIGN R-## 5) CALLSIGN CALLSIGN RRR 6) CALLSIGN CALLSIGN 73 With structured messages the text is not sent character by character, but, instead, the software uses a mathematical formula to 'translate' a call sign or grid into a unique numerical value that takes less bit space to convey than a character by character transmission format.

Structured messages can appear to exceed the 13 character limit.

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User Data

(the math details): A structured message actually consists of 3 'fields' with the lengths of 28 bits, 28 bits and 15 bits for a total of 71 bits. The 72nd bit is used as a marker and when set (1) indicates the message is 13 character text or, if unset (0) the 71 bits contain a structured message.

An amateur call sign consists of a one or two character prefix, at least one of which must be a letter, followed by a digit and a suffix of one to three letters. Within these rules, the number of possible call signs is equal to 37×36×10×27×27×27, or somewhat over 262 million. (The numbers 27 and 37 arise because in the first and last three positions a character may be absent, or a letter, or perhaps a digit.) Since 2^28 is more than 268 million, 28 bits are enough to encode any standard call sign uniquely. Similarly, the number of 4 digit Maidenhead grid locators on Earth is 180x180 = 32,400, which is less than 2^15=32,768; so a grid locator requires 15 bits in a message.” This implies that any pair of call signs [that fits the encoding rule] and a grid can be sent in 28+28+15=71 bits.

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WHAT

you need:

HF Transceiver Computer with: JT65-HF.exe software JT-ALERT.exe software SP TimeSync.exe software PC to Soundcard interface **

**

See note about soundcard on next slide

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** Special note about Soundcards: JT65-HF does

NOT

require a 'high quality' sound device as is suggested for applications like SDR (Software defined radio) usage. A high quality sound card (better SNR, better linearity, better ADC accuracy, better sample rate accuracy) may make a decode that a cheaper card will miss at the extreme lower limits of possibility, but …overall, the expense of purchasing such a card will hardly be worth the returns. In general almost

any sound card will work

with JT65-HF.

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WHERE TO LISTEN

1838 3576 7076 ~10138 14076 18102 21076 24917 28076 50076 50276 to to to to to to to to to to to JT65a-HF freq USB 1840 3578 7078 ~10140 14078 18104 21078 24919 28078 50078 50278 160 meters 80 meters 40 meters 30 meters 20 meters 17 meters 15 meters 12 meters 10 meters 6 meters 6 meters OVH - July 2013 -- by Terry WA5NTI 10

The Process:

This is typical of most digital modes.

• Audio tones are picked up by the radio (operating in Upper Sideband).

• Audio tones are sent from radio to the PC’s sound card (via line-in).

• The PC interprets the tones and prints text messages on the PC’s screen.

• You respond by typing on keyboard or clicking on mouse.

• The PC translates keyboard text to audio tones on it’s soundcard.

• The PC sends the audio tones (via line-out) to the transceiver (MIC in).

• The transceiver transmits the tones over the air.

• Your QSO partner hears the tones and sends them to his computer.

• Your QSO partner sees the text you typed and prepares to respond.

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I See The proper sequence of a JT65 QSO ( on HF ).

Assume I (WA5NTI) see VE3ODZ calling CQ and I engage in a QSO.

It would go something like the following;

( I SEE ) ( I DO )

CQ VE3ODZ FN03 1 – VE3ODZ is calling <1> CQ VE3ODZ WA5NTI CM87 call sign and grid 2 –

I answer

(((1))) VE3ODZ with my I Send WA5NTI VE3ODZ -13 (((-13))) 3 – VE3ODZ answers <2> my call with a report VE3ODZ WA5NTI R-08 (((R))) and send his (((-08))) 4 –

I acknowledge

(((2))) my report WA5NTI VE3ODZ RRR (((RRR))) 5 – VE3ODZ acknowledges <3> my report VE3ODZ WA5NTI 73 WA5NTI VE3ODZ 73 6 –

I end

(((3))) the QSO with a 73 7 – VE3ODZ ends <4> the QSO with a 73

That's it. The 'perfect' JT65 QSO.

Call signs exchanged, locations (grids) exchanged, signal reports exchanged and confirmed with R- and RRR and lastly QSO ended with the 73 messages.

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This is the First screen you see

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This is the Waterfall area OVH - July 2013 -- by Terry WA5NTI 14

This is the Text-Decode area OVH - July 2013 -- by Terry WA5NTI 15

This is the Sound Card control area (left and right channel select) (left and right volume levels) OVH - July 2013 -- by Terry WA5NTI 16

This is the Sound Card “identification” area (If your PC has more than one sound card, this area tells you which one the software is using) OVH - July 2013 -- by Terry WA5NTI 17

This is the Transceiver’s Operating Frequency (Dial Frequency) If CIV / CAT control is activated.

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“odd” vs. “even” indicator This is the previous minute (the 16 th minute - is “even” number)

Note the minute indicator (the 17 th minute - is “odd” number)

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These settings control The Waterfall This shows the text to be transmitted at time = t 0 OVH - July 2013 -- by Terry WA5NTI 20

Free Style Text entry area (max 13 characters) Automatically Generated Text Transmit audio delta (f) Receive audio delta (f) from zero ( 0 ) center of waterfall OVH - July 2013 -- by Terry WA5NTI 21

Tx / Rx Event Sequence Control Buttons

Decode Window width (within the 2 kHz waterfall) OVH - July 2013 -- by Terry WA5NTI 22

1 If You Call CQ

1) Call CQ, 2) Respond w/signal report, 3) “Roger” “Report” 1 , 2 , 3 The

“Push Button” QSO 2 If You Answer a CQ

1) Answer their QC, 2) Send Signal Report, 3 OVH - July 2013 -- by Terry WA5NTI 3) Say 73 23

Beginning of minute (a 49 sec Rx frame) OVH - July 2013 -- by Terry WA5NTI 24

AN

ESSENTIAL

free add-on product is

JT-Alert

by VK3AMA. JT-Alert is distinct from JT65-HF, but works closely with it. It looks at the decodes made by JT65-HF and then displays info and makes sounds when it detects things like someone calling CQ, or your callsign being sent by someone (such as an answer to your CQ), or a wanted state. It can also detect that you've worked someone before on the band you're on and optionally ignore any alert that may have been generated. It is a very very helpful tool that is worth installing.

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Starting the JT-ALERT companion application

Mouse-Over to see band popup display OVH - July 2013 -- by Terry WA5NTI 26

Decode Phase begins at time = 49 sec.

NOTE: no Rx text printed yet.

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OVH - July 2013 -- by Terry WA5NTI This is the relationship between the waterfall and the decoded data.

28

QUESTION

When I send someone their RST (signal report) Where do it get it ?

ANSWER

The JT65-HF software shows your partner’s signal report These signal report numbers will

automatically

show up as his/her RST in your transmitted text.

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OVH - July 2013 -- by Terry WA5NTI NOTE; You can NOT even see this decoded signal.

30

-OK Next we will start looking at some real live-captured data and walk through a real sequential JT65HF QSO

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Here we see AB0YM calling KB7N Note that AB0YM is in Grid Square CN97 Here we see AA4DD giving AG0A a “-06” signal report OVH - July 2013 -- by Terry WA5NTI 32

Here we see K5USF (who is in grid square DM62) calling CQ Note that my software used method “B” to decode this line Here we see UA6BRD calling CQ Note that my software used method “K” to decode this line OVH - July 2013 -- by Terry WA5NTI 33

These numbers report the number of “sync” vectors/pulses detected in their transmission These numbers represent the delta-t between your sound card’s clock rate and their sound card’s clock rate OVH - July 2013 -- by Terry WA5NTI 34

This Demonstrates THE POWER of JT-ALERT (helps you get QAS, QAC, DXCC …) OVH - July 2013 -- by Terry WA5NTI 35

Now to click on

“Call CQ”

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Note that we are in an

“odd”

numbered minute 2 1

START HERE

Clicking on “Call CQ” button puts a dashed line around the button Also NOTE: Pushing “Call CQ” 3 did

NOT

immediately start transmitting.

4 Because we are in an

“odd”

minute, the software will start transmitting at the top of the next

“even”

minute.

OVH - July 2013 -- by Terry WA5NTI 5 This is the text that you will transmit at the top of the NEXT minute 37

Tx began at the top of minute we are now 37 sec into the transmission Tx DF is the delta in frequency from the zero (center) of the waterfall OVH - July 2013 -- by Terry WA5NTI 38

OK Now we are going to answer someone’s CQ and do a complete QSO

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I see YO2LGK calling CQ.

To formulate a response, I just double-click on the YO2LGK line-item in the Rx Window 1 Tx is enabled, but will

NOT

start until top of the next “odd” minute 3 2 YO2LGK’s callsign and signal report are automatically generated OVH - July 2013 -- by Terry WA5NTI 40

Here we see that YO2LGK has answered our call and given us a “R” on the signal report we sent.

Also note that YO2LGK is sending us a “-04” db signal report.

When I double-clicked on his line-item, the system generated the “RRR” indicating that both ends of the QSO have “rogered” the signal reports - so, it’s a valid QSO !

OVH - July 2013 -- by Terry WA5NTI 41

Here we see that YI2LGK has received the “RRR” and has now sent “73” When I double-click on his “73” line-item the system generates “73” to be sent back to him.

The QSO is now complete.

OVH - July 2013 -- by Terry WA5NTI 42

The sending of “73” is now complete, the system is back in “Rx” mode, and “Tx OFF” is the final status.

Now all I need to do is click on the “Log QSO” button to record the completed QSO.

OVH - July 2013 -- by Terry WA5NTI 43

Click here to “log” the QSO Last chance to change things before you log the QSO This is the JT65HF logging window.

It shows you what information will be entered into your log.

If you are using DXLab like I do - the info goes into that log.

If you are not using any logging package then this information goes into a JT65HF ADIF file for you.

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If JT65HF is successful logging the QSO, this screen appears indicating the success of the operation.

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Now we want to ask the JT-ALERT system to check our log.

It will scan the log, finding the new QSO and update your “Progress Matrix” to show you where you stand as you work your way toward DXCC, WAS, WAZ ....

Click here to start the update.

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You can either “Scan All” or only scan for specific results - I want to see my DXCC status now that I have worked YI2LGK on the 10 MHz (30M) band.

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This window shows progress, as the log file is scanned.

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And, here is the scan results showing a new DXCC count for my 30M standing.

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One Final Note about QRM OVH - July 2013 -- by Terry WA5NTI 50

A Special Note About QRM Immunity ( The Resilience of JT65a )

“Just for fun this morning, I had a couple of QSOs through the S9 +20db QRM from and over the horizon radar station.

This racket (on 30m) probably emanates from Northern Australia...

Anyway,

I was astonished that I could copy stations through this

.

I hope that we spoiled their war games at least in some small measure.

73 Julian VK4CMV” OVH - July 2013 -- by Terry WA5NTI 51

THE END OVH - July 2013 -- by Terry WA5NTI 52

Configuration OVH - July 2013 -- by Terry WA5NTI 53

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JT-ALERT settings OVH - July 2013 -- by Terry WA5NTI 63

Click here with the mouse to change the configuration of settings This is a binary switch turning sound on/off Click here with the mouse to change the alerts you want the system to look for OVH - July 2013 -- by Terry WA5NTI 64

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This shows I still need QSOs with CT, ND, and West VA to have WAS OVH - July 2013 -- by Terry WA5NTI 68

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You can ask for help OVH - July 2013 -- by Terry WA5NTI 70

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You can customize these colors OVH - July 2013 -- by Terry WA5NTI 72

THE END

(OF CONFIGURATION)

SECTION 73

( questions ? )

OVH - July 2013 -- by Terry WA5NTI 73

These are the log fields if using the JT-ALERT logging.

I interface to DXXLabs OVH - July 2013 -- by Terry WA5NTI 74

The most popular JT65A frequency is in the 20 Meter band: The JT65 frequency 20metres is 14076.0 kHz USB VFO.

The JT65a sync frequency is 14077.27 kHz.

The JT65 signal frequency is about 14077.3 to 14077.7 kHz.

The JT65A frequency 30metres is 10139.0 kHz USB VFO.

The JT65a sync frequency is 10140.27 kHz The JT65 signal frequency is about 10140.3 to 10140.7 kHz*.

*Note: This transmit signal is within the 10140-10150kHz automatic digital sub-band.

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International JT65A frequency 40metres is 7039.0 kHz USB VFO.

The International JT65A sync frequency is 7040.27 kHz The JT65A signal frequency is about 7040.3 to 7040.7 kHz.

The JT65A frequency 40meters

(USA)

is 7076.0 kHz USB VFO.

The JT65A sync frequency (USA) is 7077.27 kHz The JT65A signal frequency is about 7077.3 to 7077.7 kHz.

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The JT65A frequency 17metres is 18102.0 kHz USB VFO.

The JT65A sync frequency is 18103.27 kHz The JT65A signal frequency is about 18103.3 to 18103.7 kHz.

The JT65A alternate frequency 17meters is 18098.0 kHz USB VFO.

The JT65A frequency 12metres is 24917.0 kHz USB VFO.

The JT65A sync frequency is 24918.27 kHz Note: before date 9/2011, the old JT65A frequency was 24920 kHz (changed to avoid QRM) OVH - July 2013 -- by Terry WA5NTI 77

IMPORTANT INFORMATION ABOUT ALL JT65A FREQUENCIES

• JT65A operators use USB VFO FREQUENCY for spots.

• JT65A signal is about 1.3+kHz higher than the VFO frequency.

• The JT65A Passband is about 355Hz. Bandwidth is about 200Hz.

• JT65A may be used in the 500Hz bandwidth segments of bandplans.

• Normal operation of JT65A is a sync audio frequency of 1270.5Hz.

• Sync tone is the reference mouse-click frequency for JT65.

• JT65A signal bandwidth extends about 200Hz above 1270.5Hz sync.

• The lowest tone of the JT65 signal is normally 1270Hz.

• The system allows approximately +/-600Hz auto-tuning on receive.

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Special Notes on Good Operating Procedure: 1. Operators should be careful of frequency selection, accurate clock, and calibration. 2. Always listen and observe the waterfall spectrum of signals on the frequency before transmitting, and during activity. 3. JT65A is a weak signal digital QSO mode. 4. Always use very low power on HF to avoid QRM to other JT65 signals and other modes. 5. 20Watts ERP is typical for normal activity and DXing in the 40metre to 10metre bands.

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6. Normal activity of JT65A is in the "weak signal" part of the ham bands, near the PSK, MFSK, and Olivia 500 frequencies. 7. JT65A should not be used in parts of the ham bands where faster digital modes are in use.

8. The long tone carrier duration of JT65 transmissions has potential to cause severe interference to other modes.

9. Do not use JT65 in 10144kHz-10150kHz because JT65A is NOT COMPATIBLE with MFSK, FSK, HELL, OLIVIA, CONTESTIA, ALE400, or RTTY and can cause severe interference to fast time-sharing modes such as PACKET, PACTOR, ALE, PSKmail, and APRS.

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THE END

73 ( questions ? )

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