Modulation error ratio
The modulation error ratio or MER is a measure used to quantify the performance of a
Transmitter MER can be measured by specialized equipment, which demodulates the received signal in a similar way to how a real radio demodulator does it. Demodulated and detected signal can be used as a reasonably reliable estimate for the ideal transmitted signal in MER calculation.
Definition
An error vector is a
The modulation error ratio is equal to the ratio of the root mean square (RMS) power (in Watts) of the reference vector to the power (in Watts) of the error. It is defined in dB as:
where Perror is the RMS power of the error vector, and Psignal is the RMS power of ideal transmitted signal.
MER is defined as a percentage in a compatible (but reciprocal) way:
with the same definitions.
MER is closely related to error vector magnitude (EVM), but MER is calculated from the average power of the signal. MER is also closely related to signal-to-noise ratio. MER includes all imperfections including deterministic amplitude imbalance, quadrature error and distortion, while noise is random by nature.
See also
- Error vector magnitude
- Carrier to Noise Ratio
- Signal-to-noise ratio
References
- ETSI technical report ETR 290: "Measurement guidelines for DVB systems", Errata 1, May 1997