FT8 Can Hear Them — But Can You Work Them on SSB or CW?

When using FT8, we often see signal reports like “-15 dB” and assume the band is alive with potential contacts. But what does that SNR really mean if you’re planning to call them on CW or SSB?

This article breaks down what an FT8 signal report actually translates to in human-copyable modes, helping you answer the question: “If I see them on FT8, can I work them on voice or Morse?”

Understanding SNR in FT8 vs CW vs SSB

FT8 operates in a narrow 50 Hz bandwidth and uses powerful forward error correction, which allows it to decode signals far below the noise floor. CW (Morse) is still impressively efficient, and SSB requires the strongest signal of the three.

To make a fair comparison, we reference all SNR values to a 2.5 kHz bandwidth, which is standard for SSB. This means an FT8 SNR of −20 dB in 2.5 kHz is very weak.

FT8 SNR vs Human Modes: Practical Contact Equivalence

FT8 SNR (WSJT-X, 2.5 kHz ref)	CW Equivalent (SNR for reliable copy)	SSB Equivalent (SNR for intelligible voice)	Comments
−20 dB	∼ −10 to −7 dB	Not copyable	FT8-only conditions
−15 dB	∼ −5 to −2 dB	Not copyable	Very weak signal
−10 dB	∼ +3 dB	+10 to +12 dB	CW possible, SSB difficult
−5 dB	∼ +8 dB	+15 dB	CW solid, SSB marginal
0 dB	∼ +13 dB	+20 dB	CW easy, SSB starts to work
+5 dB	∼ +18 dB	+25 dB	All modes copyable
+10 dB	∼ +23 dB	+30 dB	Armchair copy on SSB

Quick Rule of Thumb

• FT8 SNR < -10 dB: Forget SSB. Maybe CW with machine assist.
• FT8 SNR ~ 0 dB: CW good, SSB just about possible.
• FT8 SNR > +5 dB: You can probably pick them up clearly on SSB.

Why This Matters

Many operators rely on FT8 to “scout” band conditions. But seeing a waterfall full of FT8 traces doesn’t always mean you’re missing out on SSB or CW DX. It just means the band is open for extremely efficient modes.

So next time you spot that juicy DX at −15 dB on FT8, think twice before you spin the dial and try a voice call.

Unless the FT8 report is closer to 0 dB or better, it’s not likely you’ll hear much more than static.

Bottom Line: FT8 is a great indicator of propagation, but it’s not always a green light for SSB or even CW. Use the chart above to judge what modes are realistically usable based on FT8 signal reports.

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Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.