A distributed temperature sensor for transient threshold monitoring with a 22 km sensing length, based on the Brillouin loss in standard communications fibre, is demonstrated. The system can be used for real-time monitoring of a preset temperature threshold. Good S/N ratios were achieved with only 8–16 sample averages giving a response time of 2 to 4 s with a temperature uncertainty of ±1 °C.
- distributed temperature sensor
- transient threshold monitoring
- 22 km sensing length
- Brillouin loss
- standard communications fibre
- real-time monitoring
- preset temperature threshold