Method and system for metering digital demodulating error parameter based on amplitude modulation method or phase modulation method

The present invention discloses a method and a system for metering a digital demodulating error parameter based on an amplitude modulation method or a phase modulation method, wherein the metering method can comprise the following steps: generating an amplitude modulation (AM) signal the carrier frequency of which is the summation or the subtraction of a first frequency and a second frequency and the amplitude modulation frequency of which is a third frequency and an amplitude modulation depth D, wherein the first frequency is larger than the second frequency; the second frequency is over 30 times than the third frequency; VSA sample sequence persistence length is equal to integral multiple of amplitude period; using the generated AM signal as an equivalent digital modulation signal input to the input end of a VSA, wherein the carrier frequency of the VSA is set to be the first frequency; a demodulating mode is set to be MPSK; the symbol rate is set to be M times of the second frequency; and the error paramet