Table 1.
Comparison of the various passive optical fiber sensor networks based on Broadband Light Source (BLS).
| TDM-OTDR 1 | TDM-OCDR 2 | Coarse WDM | Dense WDM | |
|---|---|---|---|---|
| Optical Source | BLS | BLS | BLS | BLS |
| Interrogator | Photo detector + Oscilloscope | Photo detector + Oscilloscope | Photo detector + DAS 4 | OSA |
| Type of SU | Bend-tie sensor | FC type optical fiber connector | FBG | Optical patch cord |
| Number of channels (including reference channels) | 4 | 10 | 3 | 11 |
| Transmission length (km) | 50 | 12 | 11 | 42.5 |
| Measurand | Displacement | Water level | Tilt angle, Temperature | Water level |
| Signal processing | N/A | Required | Required | N/A |
| Self-referencing information | Required | Provided | Provided | Provided |
| Remarks | DCF 3 is required Simple | Special SU is required Rather complex | Multi-parameter Complex | Channel scalability Very simple |
| Reference | [19] | [20] | [21] | Proposed method |
1 TDM-OCDR: TDM-Optical Time Domain Reflectometry, 2 TDM-OCDR: TDM-Optical Coherence Domain Reflectometry, 3 DCF: Dispersion Compensation Fiber. 4 DAS: Data Acquisition System