Patent ID: 11920962
Assignee: NEC CORPORATION
Field: Measurement (Instruments)
Classification: CPC G  H | IPC G  H

Claim 0:
1. A surveying system comprising:
a cable that includes a first optical fiber and is provided so as to have friction between the cable and the ground, the cable being provided in such a manner that the first optical fiber is expanded and contracted in accordance with a movement of the ground;
an optical output unit configured to output a monitoring light to the first optical fiber;
a partial reflection unit that is provided on a path of the first optical fiber in the cable and partially reflects the monitoring light;
an optical reception unit configured to receive a reflection light reflected by the partial reflection unit; and
a calculation unit configured to measure the length of the first optical fiber to the partial reflection unit based on a round-trip propagation time of the reflection light that has been received and monitor its changes over time, wherein
a plurality of partial reflection units are provided at different respective points of the first optical fiber,
the calculation unit monitors the movement of the ground based on a fluctuation in the length of the first optical fiber between two of the plurality of partial reflection units,
a fixing member for adding a grip force to the ground is provided in the cable, and
a mirror transponder used for echo ranging in the sea, the mirror transponder outputting a response acoustic signal upon receiving an acoustic signal, is fixed to the fixing member.