Sensor signal processing apparatus and sensor signal processing method
In optical fiber sensors, sensor signals obtained differ according to the circumstances of installation, in locations being observed, of optical fibers serving as sensors, and it is difficult to perform accurate measurements; therefore, a sensor signal processing apparatus according to the present invention includes variation calculation means for receiving a sensor signal based on scattered light of a light pulse propagating through an optical fiber, and calculating a variation of the sensor signal from a reference value; and normalization processing means for normalizing the variation within a predetermined time, and calculating a normalized variation.
1. An optical fiber sensor apparatus, comprising:
a sensor signal processing apparatus comprising one or more memories storing instructions and one or more processors configured to execute the instructions to:
receive a sensor signal using scattered light of a light pulse propagating through an optical fiber, and calculate a variation of the sensor signal from a reference value; and
normalize the variation within a predetermined period time, and calculate a normalized variation;
a light sending circuit configured to generate the light pulse and send the light pulse to the optical fiber; and
a light reception processing circuit configured to receive the scattered light and generate the sensor signal, using the scattered light,
wherein the light sending circuit comprises a light coupler,
wherein the light coupler is configured to split the light pulse and to send, to the light reception processing circuit, a split light pulse of a part of the light pulse,
wherein the light reception processing circuit comprises:
a coherent light receiver configured to perform coherent detection on the scattered light by causing the scattered light to interfere with the split light pulse, and convert the scattered light into an analog electrical signal; and
a digital signal processing circuit configured to convert the analog electrical signal into a digital signal and generate the sensor signal.
2. The optical fiber sensor apparatus according to claim 1 , wherein the one or more processors included in the sensor signal processing apparatus are configured to execute the instructions to estimate a region in which an environmental change of the optical fiber occurs, from a difference between a transmission time of the light pulse and a reception time of scattered light of the light pulse.
3. The optical fiber sensor apparatus according to claim 1 , wherein the one or more processors included in the sensor signal processing apparatus are configured to execute the instructions to normalize the variation by dividing the variation by a maximum value of the variation within the predetermined period of time.
4. The optical fiber sensor apparatus according to claim 1 , wherein the one or more processors included in the sensor signal processing apparatus are configured to execute the instructions to normalize the variation by dividing the variation by an average value of the variation within the predetermined period of time.
5. The optical fiber sensor apparatus according to claim 1 , wherein the sensor signal is a signal using the scattered light when the optical fiber is laid along a road.
6. A sensor signal processing method for a sensor signal processing apparatus comprising an optical fiber sensor apparatus, the method comprising:
receiving a sensor signal using scattered light of a light pulse propagating through an optical fiber, and calculating a variation of the sensor signal from a reference value; and
normalizing the variation within a predetermined period of time, and calculating a normalized variation,
wherein the optical fiber sensor apparatus comprises:
the sensor signal processing apparatus;
a light sending circuit configured to generate the light pulse and send the light pulse to the optical fiber; and
a light reception processing circuit configured to receive the scattered light and generate the sensor signal, using on the scattered light, and
wherein the light sending circuit comprises a light coupler,
wherein the light coupler splits the light pulse and sends, to the light reception processing circuit, a split light pulse of a part of the light pulse, and
wherein the light reception processing circuit comprises:
a coherent light receiver configured to perform coherent detection on the scattered light by causing the scattered light to interfere with the split light pulse, and convert the scattered light into an analog electrical signal; and
a digital signal processing circuit configured to convert the analog electrical signal into a digital signal and generate the sensor signal.
7. The sensor signal processing method according to claim 6 , further comprising:
estimating a region in which an environmental change of the optical fiber occurs, from a difference between a transmission time of the light pulse and a reception time of scattered light of the light pulse.
8. The sensor signal processing method according to claim 6 , wherein the calculating of the normalized variation comprises normalizing the variation by dividing the variation by a maximum value of the variation within the predetermined period of time.
9. The sensor signal processing method according to claim 6 , wherein the calculating of the normalized variation comprises normalizing the variation by dividing the variation by an average value of the variation within the predetermined period of time.