Hertzian
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Noise Floor ChallengeEar Training

Decode Morse code messages hidden in static. As the Signal-to-Noise Ratio drops, you'll discover why digital modes and coding gain are essential for weak-signal communication.

The Noise Floor Challenge

Decode Morse code messages hidden in increasing noise. As the Signal-to-Noise Ratio drops, you'll need sharper ears — and the FFT display to help when your ears give up.

Level 1
Crystal Clear
SNR: +20 dB
Level 2
Some Static
SNR: +10 dB
Level 3
Noisy Channel
SNR: +3 dB
Level 4
At the Floor
SNR: 0 dB
Level 5
Below the Floor
SNR: -3 dB
Level 6
Deep Space
SNR: -10 dB

Understanding the Noise Floor

  • 📊What is SNR?

    Signal-to-Noise Ratio measures how much stronger a signal is compared to background noise, expressed in decibels (dB). At +20 dB the signal is 100x stronger than noise; at 0 dB they're equal; at -10 dB the noise is 10x stronger.

  • 📡The Noise Floor

    Every receiver has a minimum detectable signal level — the noise floor. It's determined by thermal noise, component quality, and bandwidth. Narrowing the bandwidth lowers the noise floor, letting weaker signals through.

  • 🛰️Why Digital Modes Work

    Modes like FT8 and WSPR can decode signals at -20 dB SNR — signals completely buried in noise. They use forward error correction and long integration times. NASA's Voyager 1 communicates at -180 dBm using the same principles.