Patent ID: 7190752

Claim:
A data signal quality evaluation method, comprising the steps of: after repeating N times (where N is a natural number) a process in which an input optical or electrical data signal with a bit rate of f 0 (bit/s) is sampled using an optical or electrical sampling pulse train, which is generated independently of the data signal, and which has a repetition frequency f 1 (Hz) which differs from the bit rate f 0 (bit/s) and satisfies f 1 =(n/m) f 0 ±a, n and m being natural numbers and a being an offset frequency, a thus obtained optical or electrical sampled signal is converted into a piece of electrical digital data, and the piece of the electrical digital data is stored in a buffer; reading N pieces of the electrical digital data stored in the buffer at once or sequentially and performing electrical signal processing of the N pieces of the electrical digital data, to obtain a signal eye-diagram and to perform data signal waveform measurement and quality evaluation.