Weak signal phase measurement method based on duffing oscillator

If the SNR (Signal to Noise Rate) of sampling data is less than -10 dB, the signal is usually called ldquoweak signalrdquo. Initial phase measurement of weak sine signal has extensive engineering application merits. When the system parameter is near its threshold, the phase to be measured is also has corresponding threshold, because the threshold is the inflexion of the system state transition, then the phase before changed can be measured by controlling the change of the phase. The main factors of measurement error are those characteristic parameters of the sampling data used in the measurement, such as signal-to-noise rate, number of samples per period of the signal to be measured and number of sampling periods, and those methods of the measurement, such as delay sampling, zeros´ space, dichotomy search and quartation of unit circle, but not parameters of simulation environment. In simulation experiment, when the signal-to-noise rate is -10dB and the frequency of the signal to be measured is known, the relative measurement error is possibly reduced to less than 1%.