Calculators & Tools
Signal-to-Noise Ratio (SNR) Calculator
Signal-to-Noise Ratio (SNR) measures how much stronger a desired radio signal is compared to the surrounding background noise. Higher SNR values generally produce clearer, more reliable communications, while lower values result in weak, noisy, or unreadable signals.
SNR is commonly used in amateur radio, digital communications, weak-signal modes, microwave systems, satellite communications, and RF engineering.
Enter signal and noise levels
Typical SNR Reference
| SNR | Typical Quality |
|---|---|
| < 0 dB | Unreadable |
| 0 – 3 dB | Very Weak |
| 3 – 10 dB | Marginal |
| 10 – 20 dB | Good |
| 20 – 30 dB | Very Good |
| 30 – 40 dB | Excellent |
| 40+ dB | Outstanding |
Practical Examples
| Mode | Typical Required SNR |
|---|---|
| Voice FM | 12 – 20 dB |
| SSB Voice | 10 – 15 dB |
| CW | 3 – 10 dB |
| FT8 | Can decode below the audible noise floor |
| JS8Call | Operates effectively at very low SNR |
| APRS | Moderate SNR preferred |
These values are approximate and vary with equipment, bandwidth, and operating conditions.
Improving Signal-to-Noise Ratio
- Increase antenna height
- Improve antenna gain
- Reduce feedline loss
- Use lower-noise coaxial cable
- Improve station grounding
- Reduce local electrical interference
- Move away from RF noise sources
- Narrow receiver bandwidth
- Use appropriate filters
- Operate during favorable propagation conditions
Practical Tips
Good Operating Practice
A stronger transmitter does not always produce a better SNR. Improving the antenna system and reducing local noise often provides greater improvement than increasing power.
Formula Reference
PowerSNR = 10 × log₁₀ (Signal Power ÷ Noise Power)Use when comparing power values (Watts, milliwatts, etc.). The multiplier is 10 because power is proportional to the square of voltage.
VoltageSNR = 20 × log₁₀ (Signal Voltage ÷ Noise Voltage)Use when comparing voltage values (Volts, millivolts, etc.). The multiplier is 20 because power scales as the square of voltage.