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JT65a

JT65a. A MINIMALIST’S ERROR FREE HAM RADIO PROTOCOL. WELCOME TO THE WONDERFUL WORLD OF JT65-HF

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JT65a

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  1. JT65a A MINIMALIST’S ERROR FREE HAM RADIO PROTOCOL OVH - July 2013 -- by Terry - WA5NTI

  2. 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. OVH - July 2013 -- by Terry - WA5NTI

  3. 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

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

  5. 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. OVH - July 2013 -- by Terry - WA5NTI

  6. 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. OVH - July 2013 -- by Terry - WA5NTI

  7. 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. OVH - July 2013 -- by Terry - WA5NTI

  8. WHATyou need: HF TransceiverComputer with:JT65-HF.exe softwareJT-ALERT.exe software SP TimeSync.exe software PC to Soundcard interface ** ** See note about soundcard on next slide OVH - July 2013 -- by Terry - WA5NTI

  9. ** 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. OVH - July 2013 -- by Terry - WA5NTI

  10. WHERE TO LISTEN OVH - July 2013 -- by Terry - WA5NTI

  11. 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. OVH - July 2013 -- by Terry - WA5NTI

  12. I See I Send OVH - July 2013 -- by Terry - WA5NTI

  13. This is the First screen you see OVH - July 2013 -- by Terry - WA5NTI

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

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

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

  17. 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

  18. This is the Transceiver’s Operating Frequency (Dial Frequency) If CIV / CAT control is activated. OVH - July 2013 -- by Terry - WA5NTI

  19. “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) OVH - July 2013 -- by Terry - WA5NTI

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

  21. 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

  22. Tx / Rx Event Sequence Control Buttons Decode Window width (within the 2 kHz waterfall) OVH - July 2013 -- by Terry - WA5NTI

  23. If You Call CQ 1) Call CQ, 2) Respond w/signal report, 3) “Roger” “Report” 1 If You Answer a CQ 1) Answer their QC, 2) Send Signal Report, 2 3) Say 73 3 1 , 2 , 3 The “Push Button” QSO OVH - July 2013 -- by Terry - WA5NTI

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

  25. 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. OVH - July 2013 -- by Terry - WA5NTI

  26. Starting the JT-ALERT companion application Mouse-Over to see band popup display OVH - July 2013 -- by Terry - WA5NTI

  27. Decode Phase begins at time = 49 sec. NOTE: no Rx text printed yet. OVH - July 2013 -- by Terry - WA5NTI

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

  29. 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. OVH - July 2013 -- by Terry - WA5NTI

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

  31. -OK- Next we will start looking at some real live-captured data and walk through a real sequential JT65HF QSO OVH - July 2013 -- by Terry - WA5NTI

  32. 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

  33. 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

  34. 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

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

  36. Now to click on “Call CQ” OVH - July 2013 -- by Terry - WA5NTI

  37. 1 Note that we are in an “odd” numbered minute START HERE Clicking on “Call CQ” button puts a dashed line around the button 2 Also NOTE: Pushing “Call CQ” did NOT immediately start transmitting. 3 This is the text that you will transmit at the top of the NEXT minute 4 5 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

  38. 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

  39. OK Now we are going to answer someone’s CQ and do a complete QSO OVH - July 2013 -- by Terry - WA5NTI

  40. Tx is enabled, but will NOT start until top of the next “odd” minute I see YO2LGK calling CQ. To formulate a response, I just double-click on the YO2LGK line-item in the Rx Window 3 1 YO2LGK’s callsign and signal report are automatically generated 2 OVH - July 2013 -- by Terry - WA5NTI

  41. 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

  42. 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

  43. 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

  44. 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. OVH - July 2013 -- by Terry - WA5NTI

  45. If JT65HF is successful logging the QSO, this screen appears indicating the success of the operation. OVH - July 2013 -- by Terry - WA5NTI

  46. 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. OVH - July 2013 -- by Terry - WA5NTI

  47. 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. OVH - July 2013 -- by Terry - WA5NTI

  48. This window shows progress, as the log file is scanned. OVH - July 2013 -- by Terry - WA5NTI

  49. And, here is the scan results showing a new DXCC count for my 30M standing. OVH - July 2013 -- by Terry - WA5NTI

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

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