Aiming at the DC output voltage signal is submerged in noise in bulky force detection which results in inaccurate results

put forward a kind of method combines periodic pulse-width modulation（ PWM） wave with stochastic resonance for DC weak signal extraction. The original signal is modulated into the signal to be measured by PWM wave. The random resonance system is used to detect the signal to be measured

and the output signal is filtered by low-pass filter

and the useful signal is restored. Through simulation experiment analysis

compare with traditional DC weak signal detection method

the error of extracted results by this method is less than that of traditional weak signal detection method

and it can achieves the purpose of detection.