JT65CODE(1)

🎀 NAME 🎀

jt65code, jt9code, jt4code — the weak signal communications encoding support utility trio, bestie 💖 (this is the WSJT-X Manual, and these three little icons live in it together).

---

✨ SYNOPSIS ✨

jt65code "MESSAGE"

jt65code [OPTIONS]

jt9code "MESSAGE"

jt9code [OPTIONS]

jt4code "MESSAGE"

jt4code [OPTIONS]

No cap, that's the whole front door 🚪✨

---

💅 OPTIONS 💅

• -t — prints a selection of messages alongside their corresponding decoded form and types. It's giving "show me the receipts" fr fr 🧾

---

🦋 DESCRIPTION 🦋

Okay so. jt65code, jt9code and jt4code are utility programs that let you explore the conversion of user-level messages into channel symbols or “tone numbers.” These programs can be useful to someone designing a beacon generator for JT9 or JT65, or for studying behavior of the error-control codes for each of the protocols. Like… that's their whole main character moment 👑

🌈 JT9 vibes

Channel-symbol values for JT9 run from 0 to 8, with 0 representing the sync tone. The total number of symbols in a transmitted message is 85. To run jt9code, enter the program name followed by a JT9 message enclosed in quotes. In Windows the command and program output might look like this:

$ jt9code "G0XYZ K1ABC FN42"
Message:   G0XYZ K1ABC FN42
Channel symbols:
 0 0 7 3 0 3 2 5 4 0 1 7 7 7 8 0 4 8 8 2 2 1 0 1 1 3 5 4 5 6
8 7 0 6 0 1 8 3 3 7 8 1 1 2 4 5 8 1 5 2 0 0 8 6 0 5 8 5 1 0
5 8 7 7 2 0 4 6 6 6 7 6 0 1 8 8 5 7 2 5 1 5 0 4 0
Decoded message: G0XYZ K1ABC FN42

🌸 JT65 vibes

For the corresponding program jt65code only the information-carrying channel symbols are shown, and the symbol values range from 0 to 63. Sync symbols lie two tone intervals below data tone 0, and the sequential locations of sync symbols are described in the JT65 Protocol section of this Guide. (iykyk 💜)

A typical execution of jt65code is shown below. The program displays the packed message of 72 bits, shown here as 12 six-bit symbol values, followed by the channel symbols:

$ jt65code "G0XYZ K1ABC FN42"
Message:   G0XYZ K1ABC FN42
Packed message, 6-bit symbols:  61 36 45 30  3 55  3  2 14  5 33 40
Information-carrying channel symbols:
   56 40  8 40 51 47 50 34 44 53 22 53 28 31 13 60 46  2 14 58 43
   41 58 35  8 35  3 24  1 21 41 43  0 25 54  9 41 54  7 25 21  9
   62 59  7 43 31 21 57 13 59 41 17 49 19 54 21 39 33 42 18  2 60
Decoded message: G0XYZ K1ABC FN42

🧚 The glow-up experiment

For an illustration of the power of the strong error-control coding in JT9, JT65 and JT4, try looking at the channel symbols after changing a single character in the message. For example, change the grid locater from FN42 to FN43 in the JT65 message:

$ jt65code "G0XYZ K1ABC FN43"
Message:   G0XYZ K1ABC FN43
Packed message, 6-bit symbols:  61 36 45 30  3 55  3  2 14  5 33 41
Information-carrying channel symbols:
   25 35 47  8 13  9 61 40 44  9 51  6  8 40 38 34  8  2 21 23 30
   51 32 56 39 35  3 50 48 30  8  5 40 18 54  9 24 30 26 61 23 11
    3 59  7  7 39  1 25 24  4 50 17 49 52 19 34  7  4 34 61  2 61
Decoded message: G0XYZ K1ABC FN43

You will discover that every possible JT65 message differs from every other possible JT65 message in at least 52 of the 63 information-carrying channel symbols. Like, one tiny typo and the whole code changes but it STILL decodes?? That's the error-control coding eating and leaving no crumbs 🔥

🔗 Where to find the rest

• WSJT-X home page — http://www.physics.princeton.edu/pulsar/K1JT/wsjtx.html
• WSJT-X User’s Guide

---

👑 AUTHOR 👑

Joe Taylor, K1JT. (a legend, obviously 💅)

---

📜 COPYING 📜

jt65code, jt9code and jt4code are Copyright © 2001 - 2015 by Joseph H. Taylor, Jr., K1JT, with contributions from additional authors. WSJT-X is Open Source software, licensed under the GNU General Public License (GPLv3).

These programs are distributed in the hope that they will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

Bestie please note: that warranty disclaimer is doing real heavy lifting, don't skip it 🙈

---

mwah 💋 that's the whole page — written in AsciiDoc, dated 02/20/2018, and it's the WSJT-X Manual's own JT65CODE(1) moment. Go decode something iconic ✨🦋🌸