The Revolutionary Digital Mode

M7ENP Amateur Radio Blog

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FT8: The Revolutionary Digital Mode Transforming Amateur Radio

TL;DR: FT8 is a weak-signal digital mode that has revolutionized amateur radio since 2017, enabling global contacts with low power and compromised antennas. It uses 15-second transmit/receive cycles and can decode signals 10-15 dB below the noise floor.

What is FT8?

FT8 stands for "Franke-Taylor design, 8-FSK modulation" - a digital weak signal communication protocol that has taken the amateur radio world by storm. Joe Taylor (K1JT), a Nobel Prize laureate, and Steve Franke (K9AN) released this mode on June 29, 2017, and it rapidly became the most popular digital mode within just two years.

FT8 is designed for making reliable contacts under challenging conditions including:

• Low solar activity periods
• High RF noise environments
• Low power (QRP) operations
• Compromised or inefficient antennas
• Weak propagation conditions

How FT8 Works

Technical Specifications

• Modulation: 8-GFSK (Gaussian Frequency-Shift Keying)
• Bandwidth: 50 Hz occupied bandwidth
• Transmission cycle: 15 seconds (12.64s transmit, 2.36s decode)
• Data rate: 6.09 bits/second (equivalent to ~5 words per minute)
• Sensitivity: Can decode signals at -20 to -21 dB S/N ratio
• Tone spacing: 6.25 Hz between tones
• Message length: 77 bits per message
• Forward Error Correction: Built-in for reliability

FT8 operates on a strict 15-second cycle where stations take turns transmitting and receiving. The protocol is semi-automated, exchanging only essential QSO information: callsigns, signal reports, and grid squares. Unlike conversational modes, FT8 focuses on quick, efficient contacts rather than extended discussions.

Understanding FT8 Signal Reports

FT8 signal reports are given in decibels (dB) and are typically negative numbers, which confuses many newcomers. Here's what they mean:

Key Point: FT8 signal reports compare your narrow 6.25 Hz signal strength to the noise level in a full 2.5 kHz SSB bandwidth. This is why reports are usually negative - your signal is below the broadband noise floor, but the sophisticated digital signal processing can still decode it!

Typical FT8 signal reports range from -24 dB (very weak) to +10 dB (very strong). A report of -15 dB indicates a perfectly workable signal, while anything above 0 dB suggests you might be running too much power.

FT8 Frequencies by Band

Band	Primary Frequency (MHz)	Alternate Frequency (MHz)	Notes
160m	1.840	-	Night time operation
80m	3.573	-	Very popular for regional contacts
60m	5.357	-	Check local regulations
40m	7.056 (Region 1) 7.074 (Global)	7.071	Excellent 24-hour band
30m	10.132 (Region 1) 10.136 (Global)	10.133	Digital-only band
20m	14.074	14.071	Most popular DX band
17m	18.100	-	Good for DX during daylight
15m	21.074	-	Solar cycle dependent
12m	24.915	-	Solar cycle dependent
10m	28.074	-	Sporadic E and solar openings
6m	50.313 50.323 (Continental only)	50.310	VHF propagation modes

Overflow Frequencies: Due to FT8's popularity, alternate frequencies have been established on busy bands. When the main frequency is crowded, try the alternate frequencies listed above, or move your dial frequency down 3 kHz from the standard frequency.

Getting Started with FT8

Required Equipment

• HF Transceiver: Any modern HF radio (IC-7300, FT-991A, TS-590SG, etc.)
• Computer: Windows, Mac, or Linux PC
• Interface: Audio/CAT interface (USB sound card, SignaLink USB, etc.)
• Antenna: Any HF antenna (FT8 works well with compromised antennas)
• Cables: Audio cables and CAT control cable

Software Setup

The primary software for FT8 is WSJT-X, available free from the official WSJT website. It supports Windows, macOS, and Linux.

WSJT-X Configuration Steps:

1. Download and install WSJT-X from the official website
2. Set up time synchronization - Critical for FT8 operation (use NTP)
3. Configure General settings:
   • Enter your callsign
   • Enter your grid square (4 or 6 character)
4. Configure Radio settings:
   • Select your radio model
   • Set correct COM port
   • Configure CAT control parameters
5. Configure Audio settings:
   • Set sound card input/output devices
   • Adjust audio levels

Critical: Time Synchronization

Warning: FT8 will NOT work without accurate time synchronization! Your computer clock must be accurate to within 1-2 seconds. Use NTP time synchronization software like NetTime (Windows) or enable automatic time sync in your operating system.

Radio Settings

• Mode: USB (Upper Side Band) on all bands, even where LSB is normally used
• Power: Start with 25-50 watts (FT8 works well with low power)
• Audio levels: Keep ALC at zero to prevent distortion
• Bandwidth: Set to 2.5-3 kHz if adjustable

Making Your First FT8 Contact

Operating Procedure

1. Select a band and tune to the FT8 frequency
2. Watch the waterfall display in WSJT-X for decoded signals
3. To call CQ: Click "Enable Tx" and the software will transmit your CQ
4. To answer a CQ: Double-click on a decoded CQ in the display
5. Follow the automated sequence: The software handles the QSO exchange
6. Log the contact when complete

Understanding the Display

The WSJT-X waterfall shows decoded signals with information like:

• Time: When the signal was received
• dB: Signal strength report
• DT: Time offset from expected timing
• Freq: Audio frequency of the signal
• Message: Decoded text (callsign, grid, report, etc.)

Advanced Features and Tips

Helper Software

• JTAlert: Provides logging integration and DX alerts
• GridTracker: Real-time map showing worked stations
• PSK Reporter: Website showing where your signals are being heard

Contest and DXpedition Features

WSJT-X includes specialized features for contesting and DXpedition operations, including:

• Fox/Hound mode: For handling large pile-ups
• Active stations display: Shows potential contest contacts sorted by points
• Distance-based scoring: For ARRL Digital contests

Why FT8 is Controversial

FT8 has sparked significant debate in the amateur radio community:

Critics argue:

• It's too automated and removes the "human element"
• It doesn't develop traditional radio skills
• It's "not really amateur radio"
• It makes DX too easy

Supporters counter:

• It keeps amateur radio relevant in the digital age
• It enables contacts impossible with other modes
• It brings new people into the hobby
• It advances weak-signal communication techniques

The Future of FT8

FT8 continues to evolve with new features and improvements. Related modes include:

• FT4: Faster version (7.5-second cycles) designed for contesting
• JS8Call: FT8-based mode allowing keyboard-to-keyboard conversations
• FST4: Designed for very weak signal conditions

Getting the Most from FT8

Pro Tips:

• Use PSK Reporter to see where your signals are being heard
• Try different bands throughout the day for varying propagation
• Monitor the waterfall to learn about band conditions
• Keep power low - FT8 works well with QRP levels
• Use proper antenna system - resonant antennas still matter
• Keep your computer time accurate - this cannot be overemphasized!

Conclusion

Whether you love it or hate it, FT8 has undeniably transformed amateur radio. It has enabled millions of contacts that would have been impossible with traditional modes, brought new operators into the hobby, and pushed the boundaries of weak-signal communication.

For the newcomer with modest equipment, FT8 offers a path to working the world. For the experienced DXer, it provides access to rare stations during poor propagation. For the technically minded, it represents a fascinating application of advanced digital signal processing.

While FT8 may not replace the joy of a good ragchew on SSB or the satisfaction of working DX with CW, it has earned its place as a valuable tool in the amateur radio toolkit. Give it a try - you might just find yourself addicted to that distinctive waterfall display and the thrill of decoding signals from around the world.

73 de M7ENP
Happy FT8-ing and see you on the digital bands!

For more amateur radio content, visit m7enp.blogspot.com

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