EVM Brief

EVM That is, the error vector amplitude , It is used to measure the integrity of the modulated signal after being processed by the nonlinear device , This modulated signal generally refers to IQ Modulation signal , Is the difference value measured relative to the reference vector signal , It is divided into IQ Phase error and IQ Amplitude error , The bevel corresponding to the amplitude error and phase error is the error vector amplitude ,EVM The relationship with bit error rate is EVM The smaller it is , The bit error rate will be better , In the actual test , Instrument required EVM It should be better than the product to be tested 5dB The above can meet the validity of the test data , Yes EVM The most important nonlinear device is the lo phase noise provided by PLL , And the background noise of high gain power amplifier , Although different digital modulation signal pairs EVM Different requirements , But a EVM Smaller devices can accommodate more types of modulated signals . For reference only ！