The Fiber Optic Sensing Distributed Acoustic Sensor (DAS) is a distributed acoustic sensing technology based on coherent Rayleigh scattering. By leveraging the optical fiber's acoustic and vibration sensitivity, it transforms standard communication cables into long-distance, continuously distributed "acoustic sensors" capable of high-precision monitoring of vibrations, sounds, and other signals with exceptional sensitivity
Working Principle: The transmitter emits high-frequency narrow-pulse lasers into the optical fiber. During transmission, Rayleigh scattering occurs, causing partial light reflection. When external vibrations act on the sensing fiber, the birefringence effect induces minute changes in both the fiber's refractive index and length. These alterations cause phase shifts in the transmitted signal, which in turn modulate the phase of scattered light. The system then performs interferometric analysis to identify disturbance locations and characteristics. Through high-speed ADC sampling, digital signal processing, and frequency domain analysis, these "interference" signals are ultimately converted into recognizable signal sources.
|
Description |
Min |
Typ |
Max |
Unit |
|
|
Sensor Distance |
|
40 |
60 |
Km |
|
|
Preheating Time |
|
1.5 |
3 |
Min |
|
|
UNL/EDFA |
|||||
|
Central Wavelength |
|
1550.12 |
|
nm |
|
|
Intrinsic light |
|
5% |
|
|
|
|
Line Width |
1.7 |
3 |
3.5 |
KHz |
|
|
Pulse Length |
60 |
100 |
200 |
ns |
|
|
Repeat Frequency Rate |
|
1 |
2 |
KHz |
|
|
Pulse Peak Optical Power |
|
|
|
mw |
|
|
AOM |
|||||
|
Extinction Ratio |
55 |
60 |
|
dB |
|
|
Up/down Time |
- |
- |
30 |
ns |
|
|
Input Impedence |
|
50 |
|
Ohm |
|
|
Frequency Shift |
|
80 |
|
MHz |
|
|
Detection Approaches |
one way |
|
|||
|
Modulation Mode |
external modulation |
|
|||
|
Type of tail fin |
|||||
|
Type of Fiber |
SMF28e 900um-Pine Casing |
|
|||
|
Tail Fiber Length (excluding head) |
99 |
100 |
101 |
cm |
|
|
Connector Type |
FC/APC |
|
|||
|
work environment |
|||||
|
Operating Temperature |
-15 |
25 |
55 |
℃ |
|
|
Working Humidity |
10 |
- |
95 |
% |
|
|
Storage temperature |
-20 |
- |
70 |
℃ |
|
|
Storage Humidity |
5 |
- |
95 |
% |
|
|
Voltage and power consumption |
|||||
|
Supply Voltage |
11.7 |
12 |
12.5 |
V |
|
|
Maximum Power |
- |
- |
30 |
W |
|
|
Working Current |
|
1 |
|
A |
|
|
Sensor Distance |
|
40 |
60 |
Km |
|
|
Preheating Time |
|
1.5 |
3 |
Min |
|

Connector model: 2EDGKM-3.81-2P curved needle
Communication interface type: XH2.54-3P
Pin definition:
|
Pin |
Name |
Attribute |
Level type |
Functional description |
|
1 |
Vcc |
|
|
+12V power supply positive |
|
2 |
GND |
|
|
+12V power ground |
|
3 |
TXD |
O |
RS232 |
RS232 communication transmitter |
|
4 |
RXD |
I |
RS232 |
RS232 communication accept extreme |
|
5 |
GND |
GND |
|
|
unit :mm
