Digitial detecting method of electric or magnetic field sensing signal based on light source modulation

The advantage and disadvantage of the conventional detecting methods of electric or magnetic field sensing signal in the fiber optical sensing system are discussed. A new digital detecting method of electric or magnetic field sensing signal based on the optical modulation and electrical demodulation is proposed in order to eliminate the power frequency and low frequency noises. The digital detecting circuit is designed and the detecting software is developed. In design of the circuit, because the closed-loop synchronous sampling technique is used, not only the leakage effect is controlled and the detecting accuracy is increased, but also the signal processing is simplified, so it has better real-time characteristics. The experiments show that the test results detected by this method have good linearity.