In this article lets check out which parameter weighs in more to determine the signal quality when we have complex modulations like PCS and QAM come Into picture .Let's recap
- EVM (Error Vector Magnitude): Measures the deviation of received signal points from their ideal positions, capturing various impairments like noise, distortion, and timing errors.
- BER (Bit Error Ratio): Directly measures the ratio of incorrectly received bits to the total transmitted bits, reflecting decoding errors but not revealing underlying causes.
Now why EVM is more relevant:-
- Higher sensitivity to impairments: Complex modulations have densely packed constellation makes it highly sensitive to even slight deviations, which EVM detects more effectively than BER.
- Faster measurement: EVM can be calculated quickly without extensive error counting, making it suitable for real-time monitoring.
- Detailed insights: EVM pinpoints specific sources of degradation, aiding troubleshooting and optimization efforts, unlike BER which only indicates errors.
In detail with a small Example:
- Imagine noise distorting 64QAM signals. EVM would reveal these deviations, even if no bit errors occur yet, enabling proactive measures. BER would remain low until noise levels cause actual bit flips, potentially delaying corrective actions.
Conclusion :- Not saying that we should stop checking BER however when we have the option of EVM , we should have a look at that first as it would have early detection