Introduction to Ham Radio Digital Modes Including FT8
Steve Ikler, KS3K October, 2018 Some slides and information in this presentation are used with permission from Dave LeVasseur, N0DL and the Lake Area Radio Klub (SD) Methods of Ham Radio Communication
• CW (Morse Code) • Voice (SSB, FM, AM, Digital Voice) • Digital (binary, either on or off) – Uses computers, sound cards and software – Converts text messages into audio – The audio gets transmitted – Translates audio back into readable text Why Use Digital Modes
• Efficient use of bandwidth • Efficient use of power • Even small, indoor or compromise antennas work well • Still usable when voice or cw cannot be heard • Very popular worldwide • Work DX with minimal station • Foreign accents not a problem – it’s all text • Can send images (SSTV, Winlink) Examples of Digital Modes
• CW • RTTY (FSK and AFSK) • PSK (BPSK, QPSK, PSK31, PSK63, PSK125) • *-TOR (Amtor, Pactor, G-Tor, etc.) (Packet) • JT-Modes (Joe Taylor, K1JT) – JT65, JT9, WSPR, MSK144, FT8 • Others – Olivia, CONTESTIA, Feld Hell, MFSK, MT63 What Do You Need
• Transceiver • Computer (Laptop/Desktop) • Audio Interface between computer and radio • Software
http://www.tigertronics.com/ http://www.westmountainradio.com/ Digital Software
• Ham Radio Deluxe (DM780) (Not Free) • Fldigi • WinWarbler (DXLabs) • WSJT-X • RMS Express (Winlink) • MMTTY • MixW Summary of PSK Former King-of-the-Hill • Phase-Shift Keying - Changes (modulates) the phase of a constant frequency reference signal (the carrier wave) • Also used by Wireless LANs, RFID, Bluetooth • BPSK and QPSK – Binary Phase-Shift Keying and Quadrature Phase-Shift Keying • BPSK much more popular • Conversational Mode – Instant Messaging without the internet
Summary of FT8
• FT8 is named after its developers, Steven Franke, K9AN, and Joe Taylor, K1JT. • The “8” denotes 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. • Contacts are four times faster than with JT65 or JT9, and an entire FT8 contact can take place in about 1 minute. FT8 has become EXTREMELY popular
Mode Usage Evaluation: 2017 was “the Year When Digital Modes Changed Forever” – QRZ NOW.com, January 22, 2017 What FT8 Can Do
• 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. • Works well for EME (“moonbounce”), meteor scatter and other modes where Doppler shift would otherwise render communications difficult or impossible Strengths ● Good for weak signals ● Signals just 50 Hz wide ● Can still be decoded if signals overlap ● Minimal QSO info passed reliably ● Popular – Lots of activity Weaknesses ● Mechanized, no personal touch ● Slow communication speed ● Complex and confusing to beginners ● Problems with non-standard calls DXpedition Mode
● For DXpedition stations and those seeking to work them ● Enables very high QSO rates ● Fox and Hound ● DXpedition station is the “Fox” ● Calling stations are the “Hounds” DXpedition Mode
● Minimal exchanges for faster QSOs ● Foxes can make up to 5 QSOs simultaneously ● Used outside normal FT8 sub-bands ● Uses “Split” operation ● Baker Island DXpedition – 24% of all QSOs were using FT8 (16,670 out of close to 70,000 total) How FT8 Works
• All QSOs consist of data blocks sent and received in synchronized 15-second intervals. • The software uses your computer’s soundcard to decode and display multiple received signals and also to encode your transmitted CQ or response • Uses lots of overhead error correction in the message To reach down into and below the noise floor. The effective data rate is about 5 WPM. Sync Your PC to UTC
• You need to sync your PC to ±1 second of UTC • https://www.time.is – to check your PC vs UTC • The built-in Windows facility for time synchronization is usually not adequate. Try the program Meinberg NTP (see Network Time Protocol Setup for downloading and installation instructions) • Or Dimension 4 from Thinking Man Software. The “Maidenhead” Grid Squares
• Developed by Dr. John Morris G4ANB of Maidenhead, England in 1980 • Divides the earth into 324 fields
More info: https://en.wikipedia.org/wiki/Maidenhead_Locator_System Getting Started Adjust slider until t (Set the band, tune Use Tune to check up as normal power level 10% is a good place to start)
You will probably need to adjust your sound Adjust RF gain to keep receive level card’s audio levels to get everything to play. below red, between 40 and 80 is ok This can take some time and a separate sound card is highly recommended (set and forget) All QSO activity WSJT-X Main Screen in the receive All activity shown spectrum on the Rx frequency
Stations calling Y“CQ” will be highlighted in are highlighted in green yellow
The message transmissions are Your call will show generated up highlighted in automatically and red sent in sequence Y are sent in a 50 H base frequency + the audio offset What FT8 Looks Like
15-second segments (offset between the green lines) where stations alternately transmit and receive JS8Call
● New mode by Jordan Sherer KN4CRD ● Based on popular FT8 Mode ● Keyboard-to-keyboard message handling ● Currently in Pre-Release versions ● Formerly called FT8Call ● http://js8call.com How’s My Signal? You can use PSK Reporter, https://pskreporter.info to see how well your signal is being received throughout the world (this works for just about all modes, not just FT8). Here is a snapshot of the map for N0DL on 40m, 1150 UTC March 9th, 2018: Questions?
Thanks for your attention! Time Sync Software
• The built-in Windows facility for time synchronization is usually not adequate. We recommend the program Meinberg NTP (see Network Time Protocol Setup for downloading and installation instructions) or Dimension 4 from Thinking Man Software. Additional References and Links
• 1WSJT User Guide: http://physics.princeton.edu/pulsar/k1jt/wsjtx-doc/ wsjtx-main-1.7.1-devel.html • 2The World’s Ugliest Music TED Talk • 3Download link for WSJT-X: https://physics.princeton.edu/pulsar/k1jt/wsjtx.html • FT8 Operating Guide: http://www.physics.princeton.edu/pulsar/K1JT/FT8_ Operating_Tips.pdf Additional References and Links
• 4DX Lab Suite including Commander: http://www.dxlabsuite.com/commander/
• Digital modes for the beginner: http://ve6mvp.com/beginnersdigital.htm
• Buxcom Rascal Mark IV soundcard + interface: https://packetradio.com/catalog/index.php?main_page=index& cPath=50
• CQ article, “The Genius of Joe Taylor” http://www.cq-amateur-radio.com/cq_highlights/2017-cq/201 7-09-cq/2017-09-cq-zero-bias.html