“Modulation Error Ratio”

MER should not be confused with SNR (Signal to Noise Ratio)! Although there is a certain relationship, namely, the noise on the modulator can increase the MER of the digital modulator.

MER, the “Modulation Error Ratio,” should be considered an essential metric in digital communication systems, especially those systems employing digital modulation like DAB+.

Unlike continuous analog signals, digital modulation involves modulating a discrete sequence of bits. Digital modulation in DAB+ uses phase shifts on all the carriers. Four shifts are used to transmit two bits in one modulated symbol. The accuracy of a phase shift depends on the phase noise, which disturbs the accurate phase detection in the demodulator. Also, amplitude (amplitude noise) changes can make detecting the symbols more difficult.

The significance of MER becomes even more pronounced when we consider its role in accurately quantifying the delivered modulation quality of DAB+ transmitters, a crucial aspect of their performance evaluation. This underscores the importance of your work in ensuring high-quality transmission.

A measuring receiver’s task is to replicate the transmitted signal with utmost precision. The crucial point is that the measuring receiver should not introduce additional errors that could affect the measurement. The received bitstream is meticulously compared to the bitstream at the transmitter’s modulator input to achieve this, emphasizing the critical role of engineers and technicians in maintaining the accuracy of digital communication systems. 

High-end DAB+ transmitters have a typical MER above 33dB.
Low-end DAB+ transmitters often do not mention the MER, making evaluating them difficult. We can ask ourselves why they hide the MER parameter. We think the answer is in the answer to the question.

The MER value directly impacts the transmitter’s tolerance for generated modulation errors. A higher MER translates to a lower tolerance, indicating a more stringent requirement for error-free transmission. In other words, a better transmitter MER results in receivers that can pick up the signal more accurately without introducing additional errors. This highlights the need for meticulous work to maintain a high MER for error-free transmission.


The MER expressed in dB corresponds to 10*LOG10 of the ratio Psignal/Perror (Power ratio). A ratio of 33dB corresponds to 103,3 or 1995

The MER in % is the square root of the inverse ratio or the square root of 1/1995 multiplied by 100% or a MER of 2,23% errors

We should consider that the practical transmit path (the wireless channel) will also introduce errors. However, the best start is using a transmitter that transmits a signal with a Modulation Error Rate (MER) as low as possible.

Like always, starting with the best quality gives the highest probability of ending with the highest quality. A good start is half the battle won!