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. In the case of OFDM waveforms use this tool.

## 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*log_{10}(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 |