WSJTX Archive

Technical

WSJT-X 2.0 Will Be a Mandatory Update

ARRL, The national association for Amateur Radio, reports that Significant Changes [are] in Store for FT8 and MSK144 with WSJT-X Version 2.0:

WSJT-X co-developer Joe Taylor, K1JT, has announced that major changes are coming to the FT8 and MSK144 digital protocols when WSJT-X version 2.0 arrives in a few months. Taylor said version 2.0 should be ready for prime time by January.

The “Significant Changes” article lists a potential WSJX-X 2.0 features—including ARRL Field Day operation with standard Field Day exchanges and A special telemetry message format for exchanging arbitrary information up to 71 bits—which, according to K1JT, will “work seamlessly and automatically … No contest mode checkboxes are needed”.1

These new features will not be backwards compatible. “It will be essential for users to upgrade to version 2.0 in order to use the new features and communicate with others who have made the upgrade.”2

  1. “Significant Changes in Store for FT8 and MSK144 with WSJT-X Version 2.0”, ARRL The national association for Amateur Radio, retrieved July 27 2018, http://www.arrl.org/news/significant-changes-in-store-for-ft8-and-msk144-with-wsjt-x-version-2-0. ↩︎

  2. “Significant Changes in Store for FT8 and MSK144 with WSJT-X Version 2.0”, ARRL The national association for Amateur Radio, retrieved July 27 2018, http://www.arrl.org/news/significant-changes-in-store-for-ft8-and-msk144-with-wsjt-x-version-2-0. ↩︎

Technical

Introduction to WSJT-X FT8

FT8 is a new mode included in WSJT-X versions 1.8 and later.

This weak signal mode is intended—and optimised—for making efficient barebones contacts; a definite plus during this time of poor propagation. Although FT8 does not support rag-chewing or contesting exchanges it is, none the less, well worth trying out in the Amateur Radio spirit of learning and experimentation.

The slides from my presentation after the adjournment of the April 17, 2018, RRRA Business Meeting are available for download from the Training and Education | Presentations folder on the RRRA Groupware Server.

About FT8

The new mode is named after its developers, Steven Franke, K9AN, and Joe Taylor, K1JT. The numeral designates the mode’s 8-frequency shift keying format. Tones are spaced at 6.25 Hz, and an FT8 signal occupies just 50 Hz. Unlike JT65 or JT9, transmit and receive cycles in FT8 each last about 15 seconds. Like JT65, FT8 requires accurate time synchronization. An auto-sequencing feature offers the option to respond automatically to the first decoded reply to your CQ.

“FT8 is an excellent mode for HF DXing and for situations like multi-hop Es on 6 meters, where deep QSB may make fast and reliable completion of QSOs desirable,” Taylor’s release notes assert. 1

  1. “FT8 Mode is Latest Bright Shiny Object in Amateur Radio Digital World”, ARRL The national association for Amateur Radio, retrieved April 18 2018, http://www.arrl.org/news/ft8-mode-is-latest-bright-shiny-object-in-amateur-radio-digital-world. ↩︎

Education

FT8 Presentation at April Club Meeting

All Hams interested in FT8 are encouraged to attend KA0LDG’s presentation about this mode at the April RRRA Club Meeting

KA0LDG is planning to present a Power Point briefing about FT8 followed by a live demonstration of the mode using his portable station.

Please direct all questions about this upcoming presentation to .

Technical

New FT8 Mode included in WSJT-X Beta Release

WSJT-X version 1.8.0 includes a new mode named FT8

This mode features:

  • QSOs 4 times faster than JT65 or JT9
  • Sensitivity down to -20 dB on the AWGN channel
  • Auto-sequencing includes an option to respond automatically to first decoded reply to your CQ

WSJT-X source code; along with installation packages for Windows, Linux, OS X, and Raspbian; is available for download at http://physics.princeton.edu/pulsar/K1JT/wsjtx.html

About the FT8 protocol

WSJT-X Version 1.8.0 includes a new mode called FT8, developed by K9AN and K1JT. The mode name “FT8” stands for “Franke and Taylor, 8-FSK modulation”. FT8 uses 15-second T/R sequences, provides 50% or better decoding probability down to -20 dB on an AWGN channel, and maintains good performance on Doppler-spread fading channels. An auto-sequencing facility includes an option to respond automatically to the first decoded reply to your CQ. FT8 QSOs are 4 times faster than those made with JT65 or JT9. FT8 is an excellent mode for HF DXing and for situations like multi-hop E_s on 6 meters, where deep QSB may make fast and reliable completion of QSOs desirable. [ 1 ]

Some important characteristics of FT8:

  • T/R sequence length: 15 s
  • Message length: 75 bits + 12-bit CRC
  • FEC code: LDPC(174,87)
  • Modulation: 8-FSK, tone spacing 6.25 Hz
  • Constant-envelope waveform
  • Occupied bandwidth: 50 Hz
  • Synchronization: 7x7 Costas arrays at start, middle, and end
  • Transmission duration: 12.64 s
  • Decoding threshold: -20 dB; several dB lower with AP decoding
  • Multi-decoder finds and decodes all FT8 signals in passband
  • Optional auto-sequencing and auto-reply to a CQ response
  • Operational behavior similar to JT9, JT65

Footnotes

[ 1 ] “WSJT-X Release Notes”, Joe Taylor K1JT, retrieved July 18 2017, https://physics.princeton.edu/pulsar/k1jt/Release_Notes_1.8.0.txt.