This tool converts from Error Vector Magnitude (EVM) to Signal-to-Noise Ratio (SNR).
In order to calculate SNR the following are required:
- EVM% (use this tool to convert from dB to %)
- Peak-to-Average Power Ratio (PAPR). Use the table below to find the PAPR of a modulated signal.
Formula
SNR = – [PAPR + 20 * Log10 (EVM% / 100)]
Example EVM to SNR calculation
If you want to calculate the SNR for QPSK waveform for instance, use the PAPR value of 1.76 dB from the table below in the calculator above.
For a 1% EVM, the SNR is 38.24 dB. As the EVM increases the SNR degrades and at a certain point it will become difficult to demodulate the signal.
Peak-to-Average-Power-Ratio Values
Below is a table of PAPR values for different modulation formats. These can be used in the calculator.
| Waveform | PAPR (dB) |
| Sine Wave | 3.01 |
| Full-wave rectified sine | 3.01 |
| Half-wave rectified sine | 6.02 |
| Triangle wave | 4.77 |
| PWM signal | 10*log10(T/dT) |
| QPSK | 1.76 |
| 8-PSK | 3.3 |
| π⁄4-DQPSK | 3 |
| OQPSK | 3.3 |
| 64-QAM | 3.7 |
 -QAM | 4.8 |
| WCDMA downlink carrier | 10.6 |
| OFDM | 12 |
| GMSK | 0 |
| Gaussian noise | |
| Periodic chirp | 3.01 |