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HF Digital Modes, Including FT-8

Neil Goldstein, W2NDG

HRU 2022

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Digital Modes

  • What is a digital mode?
    • We’re referring to digital text modes for the purposes of this discussion
    • An Amateur digital mode is a radio mode where characters are sent by a chosen form of modulation and encoded using an open code (not encrypted for security)
    • Most of these can be heard as tones, blips, musical notes, or organized noise
    • Technically, CW is a digital mode

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Digital Modes

  • CW, RTTY
  • PSK31 (and other PSK derivatives)
  • Olivia, Contestia, Domino
  • Hellschreiber (or Hell)
  • Packet, MT63
  • JT65, FT8, FT4, JS8
  • WSPR (not really a QSO mode)
  • Pictures too
    • WeFAX and SSTV

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Software

  • FLDIGI
  • WSJT-X
  • JS8-CALL
  • Ham Radio Deluxe – DM780
  • WinLink
  • Others: MixW, MultiPSK, JTDX, MSHV

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  • We’re going to discuss WSJT-X mostly

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Joe Taylor (Joseph Hooton Taylor Jr.)

  • That’s what the “JT” in WSJT stands for
  • As well as the “T” in FT8
  • Joe is an Astrophysicist and won a Nobel Prize for his work with pulsars
  • Lucky for us, he’s also interested in Ham Radio, and goes by K1JT
  • It’s Joe’s interests in weak signal communications that brought us these wonderful modes and applications

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Joe Taylor

So….. This happened since last year:

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Joe Taylor

  • Joe spoke at the Hudson Division awards luncheon in November of this year.
  • His original vision for the software was to be able to leverage computer power to aid in encoding and decoding low power digital communications.
  • He spoke a bit about the origin of WSJT-X software, and the brilliant developers he’s had helping him.
  • Joe talked about the future of WSJT modes and leveraging SDR technology to get out of the bandwidth restriction.
  • If you ever have a chance to see him speak, pleas do!

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WSJT-X Uses

  • Weak signal communications:
    • Moon Bounce (EME)
    • Meteor Scatter
    • Propagation Reporting
    • And.. Digital QSOs (unintentional at first)
  • Modes (HF)
    • JT9, JT65, FT8 & FT4 for QSO’s
    • WSPR (which is a non QSO mode)

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Interfacing

  • We need connections that provide:
    • CAT control of your rig
    • Two-way audio

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  • Older rigs may require serial-to-USB interfacing and audio connections

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  • Many modern rigs (IC-7300 for example) offer a single connection for both.

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  • For audio linking, consider an audio interface like the Signalink or EasyDigi

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  • The best way to figure out the connections is to search for WSJT-X + Your Rig Model. In my case I would search for: Icom IC-7300 WSJT-X You will see both step-by-step web pages, and YouTube tutorials.�

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WSPR

  • WSPR (Weak Signal Propagation Reporter)
  • NOT a QSO mode
  • Low power transmissions are made in a 2-minute cycle. Transmitting stations report their location and power to the WSPR system.
  • Receiving stations report stations received, and location.
  • All of it is added to a data base and displayed on a map for propagation usage.

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JT65

  • Originally intended for EME and other similar conditions, Hams started using JT65 on the HF bands. Several features were added to facilitate HF use.
  • Signals are sent with FEC (forward error correction) and are capable of being decoded when being below the noise floor. Each signal uses 65 tones and is just under 180 hz wide.
  • Each part of a JT65 exchange takes one minute.

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Timing

Getting this to work (JT65 or FT8) requires things to be time synchronized. Everyone needs to be transmitting or receiving at the same interval.

There are a few seconds included as a buffer, but your computer’s clock needs to be EXACT.

You should install software to assist with the clock setting, otherwise you will need to manually synchronize often.

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Time Sync Software

Windows

Meinberg NTP. Instructions at the WSJT-X site

MacOS

You can change your time sync settings in System Preferences

Linux

Out of the box settings may be OK, but if not, you may need to choose a different time server, and update interval. Google is your friend!

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Typical Exchange

  • CQ K1ABC FN42 #K1ABC calls CQ

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  • K1ABC G0XYZ IO91 #G0XYZ answers

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  • G0XYZ K1ABC –19 #K1ABC sends report

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  • K1ABC G0XYZ R-22 #G0XYZ sends R+report

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  • G0XYZ K1ABC RRR #K1ABC sends RRR

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  • K1ABC G0XYZ 73 #G0XYZ sends 73

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“The “A” Word

  • A small amount of automation is present
  • Once you “jump” on a signal, the major steps can be automatic
  • If choose to call CQ first, the process is even more automatic once someone responds.
  • Any more automation than that is not discussed here.

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Power

  • Yes, JT-65 was originally thought of as a low power mode, but not for the reasons you think.
  • Duty cycle made it that way. Running your transmitter flat out on MFSK for 50 seconds straight is not a great thing.
  • FT8 fixes this, as well as speeding things up just to dial back the boredom involved with 6 x 60 second portions of a full exchange

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Enter: FT8

  • FT8 was developed jointly by Joe Taylor and Steve Franke (K9AN).
  • Same basic features and rules as JT65, but the interval drops from 60 seconds to 15 seconds. Timing is now MORE IMPORTANT!
  • The original idea was a mode for multi-hop Es where signals may be more prone to fading. JT65 fans had other plans though

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FT8 Technical Info

Eight tone MFSK

47hz Bandwidth

Decoding threshold = -20db

Decodes all signals in the passband

Speed Speed Speed

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Where do I get it?

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  • But wait…. Stop trying to write this down.
  • Just GOOGLE IT!
  • Google: WSJT-X

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Keep your installs up to date!�Changes sometimes occur that will leave you behind.

  • Windows
    • Runs on Windows XP, 7, 8, 10 both 32 and 64
  • Linux
    • Builds for
      • Debian based distros (.deb)
      • RedHat based distros (.rpm)
      • Raspbian on Raspberry Pi
  • Mac OS/X
    • 10.13 and later (read the readme file!!)

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Recent Changes and Additions

    • Q65 for EME, and other weak – scatter VHF/UHF uses
    • Improved HamLib support by moving HamLib to a DLL file, allowing for upgrades and bug fixes without touching the program code itself
    • WSPR now generates a tone for tuning while band hopping
    • Numerous bug fixes and UI improvements

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Easy setup (Except on MacOS)

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Setup Continued…

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Setup Continued…

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Setup Continued…

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Setup Continued…

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Setup Continued…

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Main Window

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Main Window

The left window shows band activity. Green means someone sending CQ, while Red are transmissions directed at you.

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Right window shows activity on the receive frequency and your transmissions (Yellow).

Double clicking on a green CQ starts the process. You have to be quick!

If you miss, you will re-transmit the response in the next transmit cycle

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You can edit the exchanges. Most people leave them defaulted.

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New Since Last Update

CQ Only Checkbox. Shows only CQs in band activity.

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New Dark Style

Hold Tx Frequency Checkbox. Holds TX frequency when double clicking to respond.

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“Wide Graph” (Waterfall)

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“Wide Graph” (Waterfall)

  • Clicking on the waterfall changes receive frequency

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  • Control-click changes transmit frequency

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Split Mode

  • Significant advantages result from using Split mode (separate VFOs for Rx and Tx) if your radio supports it. If it does not, WSJT-X can emulate such behavior. 
  • Either method will result in a cleaner transmitted signal, by keeping the Tx audio always in the range 1500 to 2000 Hz so that audio harmonics cannot pass through the Tx sideband filter.
  • Select Rig to use the radio’s Split mode, or Fake It to have WSJT-X adjust the VFO frequency as needed, when T/R switching occurs. Choose None if you do not wish to use split operation. – WSJT-X Manual

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Contest Mode

  • A special NA VHF Contest mode can be activated for FT8 and MSK144 modes by checking a box on the main window. This mode is configured especially for contests in which four-character grid locators are the required exchange. When NA VHF Contest mode is active, the standard QSO sequence looks like this:

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  • CQ K1ABC FN42
  • K1ABC W9XYZ EN37
  • W9XYZ K1ABC R FN42
  • K1ABC W9XYZ RRR
  • W9XYZ K1ABC 73

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Add On

  • JTAlert from hamapps.com

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Add On

  • JT-Bridge(MacOS) from jt-bridge.eller.nu

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FT8 Guide by ZL2IFB

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  • This is all you need really. We could spend way too much time here talking about details. Just read this guide!!

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FT4 Mode – What is it?

  • Mode for contesting (mostly)
  • 4 FSK tones spaced ~20 Hz apart instead of 8 tones ~6 Hz apart, hence FT4 vs. FT8
  • 7.5 Sec. transmissions – half the time
  • WSJT-X modes are becoming more prevalent in contests. FT4 allows more QSOs in the same amount of time

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JS8Call – What is it?

  • Designed by Jordan Sherer, KN4CRD
  • Jordan Sherer Designed MSK-8 : JS8
  • Originally known as FT8Call
  • Applying a conversational mode to the FT8 principle. Conversations occur at approximately 5 - 15 words per minute
  • User guide here: https://tinyurl.com/yc6z73do

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JS8Call

  • Newer versions support 4 speeds
    • Slow, Normal, Fast, and Turbo
    • 30, 15, 10, and 6 second frames
    • Faster computers can decode all 4 at once
    • The idea otherwise is to start in NORMAL and move to a faster mode (or slower) depending on conditions

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JS8Call

  • Three types of messages
    • Standard
      • Similar to PSK31. Keyboard to keyboard
        • Only works if you are 10Hz apart
    • Undirected
      • For CQ mostly
    • Directed
      • To specific call or @ALLCALL or a group call

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JS8Call Main Screen

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New FT8 Radio Kits

  • D4D DSB Transceiver Kit (CRKits.com)
  • 13 Transistor Txcvr for Digital (CRKits)
  • DSB Digital Transceiver Kit
  • AFP-FSK Dig Transceiver III (QRPGuys)
  • K1SWL’s Phaser Digital Mode SSB Kit
  • QDX - Digital Transceiver (QRP-LABS)

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DSB Controversy

  • Second signal is transmitted in LSB
  • For example: when transmitting on 20M LSB signal will appear in the 20M PSK sub-band. Not illegal as such, but could be annoying.
  • At 1 Watt (500 mw actually) may not be a huge issue, but….
  • Two DSB transceivers are unable to communicate

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Portable Setup

  • Use a Raspberry Pi with LCD screen
  • Completely portable Digital mode rig
  • Just needs battery power (12V and 5V)

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  • Remote operation: PC and Internet with remote desktop or other remote software like TeamViewer, or RDP

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Portable Setup

  • Smart Pi Touch 2 Case https://www.amazon.com/gp/product/B07WXK38YM/
  • Pi 4 8GB
  • QRP-LABS QDX
  • Mini Keyboard-Mouse Combo
  • Ham Pi Distro

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D4D From CR Kits

  • DSB (controversial)
  • Available for FT8 80, 40, and 20 M
  • Available for JS8Call 30 M
  • $39 Plus shipping from CRKits
  • About 1 Watt

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  • Here’s the one I built:

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D4D From CR Kits

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13 Transistor Txcvr for Digital (CRKits)�

  • 1 Watt output on 40 M

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AFP-FSK Dig Transceiver III (QRPGuys)

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AFP-FSK Dig Transceiver III (QRPGuys)

  • 160 – 10 M with band modules
    • Comes with 40/30/20
  • Works for FT8, JS8Call, WSPR, RTTY
  • Additional blank band modules available
  • 5W up to 15M, 4W 12 and 10M
  • DDS VFO
  • Designed by KD1JV, Steve Weber

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QRP-LABS QDX

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QRP-LABS QDX

  • 80, 40, 30, and 20 M
  • Works for FT8, JS8Call, WSPR, RTTY
  • 5W output at 9Volts
  • Full USB control from WSJT-X and other compatible software
  • New terminal-based setup, and easy firmware update
  • Professional case available

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Have Fun!

  • Ignore the trolls!
  • Questions? neil@neilgoldstein.com
  • All links and this presentation can be found at:

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FOFIO.BLOGSPOT.COM

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