DAS Integration Module Supporting Customized Pulsed RF Input

Summarize

This DAS module integrates the optical path for Distributed Acoustic Sensing (DAS). It features a built-in AOM that supports both RF and digital TTL-modulated inputs; therefore, the user must input an 80 MHz or 200 MHz RF signal, which is then modulated into pulses via a TTL-modulated signal.

This DAS integrated module is a highly integrated core optoelectronic kit designed specifically for high-performance distributed acoustic fiber sensing systems.

The module integrates a narrow-linewidth laser, an AOM, an EDFA optical amplifier, a balanced photodetector, and a precision hardware clock synchronization circuit within an ultra-compact housing.

When used in conjunction with our proprietary DAQ+AWG architecture high-speed data acquisition card, this DAS module offers superior clock synchronization compared to traditional solutions that rely on a common clock source for the AOM and DAQ. The DAS’s AOM is driven by RF pulses generated by the AWG, ensuring not only full clock synchronization with the DAQ but also complete consistency in the initial phase of the pulses. This enables high-speed acquisition and real-time demodulation of all-fiber signals, thereby significantly enhancing the system’s demodulation stability and reliability in long-distance and weak-signal scenarios. Users can rapidly build fully real-time, long-distance, high-resolution, industrial-grade DAS measurement systems.

Features

• High integration
• Modular design
• High-precision clock synchronization
• High stability and reliability
• Customizable form factor

Applications

• Optical Research
• Perimeter Intrusion Monitoring
• Oil and Gas Pipeline Leak Early Warning
• Railway Corridor Safety Monitoring
• Structural Health Monitoring of Tunnels and Slopes
• Condition Monitoring of Submarine and Land Cables
• Vibration Monitoring of Urban Infrastructure

Internal Optical Path Diagram of the Module

Core Parameters

Ultra-Narrow Linewidth Laser Source Parameters

Pulse EDFA Parameters

Acousto-Optic Modulator Parameters

Raman Amplifier (Optional) Parameters

Differences between this module and other standard DAS modules

This module supports full-range RF signal input. For example, if you select a DAS module designed for a 200 MHz intermediate frequency signal, you can use an AWG to directly output a 200 MHz signal. Alternatively, you can provide your own chirped pulse signals to achieve higher-performance DAS.

Interface Definition

Mechanical Dimension Drawing

What kind of capture card is needed?

Since this DAS module requires the output of 80/200 MHz RF signals, the data acquisition card must include an AWG function. To meet this requirement, we have specifically developed a 1 Gbps high-speed data acquisition card that also integrates an AWG function.

GY-DAQA-2510， View Detail

The pulse modulation of the DAS module is generated by the RF pulse modulator on the acquisition card, and the TTL trigger output signal from the acquisition card is used to enable modulation of the module.

Schematic Diagram of the Connection Between the GY-DAQA-2510 and the DAS Module

1. Connect the AWG1 pin on the data acquisition card to the RF input of the DAS module.
2. Connect the trigger output of the data acquisition card to the modulation input of the DAS module.
3. Connect CH1 on the data acquisition card to CH1 on the DAS module.
4. Connect CH2 on the data acquisition card to CH2 on the DAS module (if the DAS module has only one sensor fiber, this connection is optional).

Two Combinations with the Capture Card

Option 1: Use this DAS module and the GY-DAQA-2510 to build a DAS system for chirp pulses.

For this solution, you must configure the AWG output signal of the GY-DAQA-2510 yourself. You can set the chirp pulse waveform, and then the data acquisition card will capture the raw data, which you will need to demodulate yourself.

GY-DAQA-2510 view more

Option 2: Use this DAS module and the GY-DAQ-2510DA to build a DAS system with full-clock synchronization.

With this solution, the GY-DAQ-2510DA can output the required 80M/200M RF signals as well as triggered TTL signals, and demodulation is already implemented within the acquisition card’s FPGA. This makes it more convenient to use.

GY-DAQ-2510DA  view more

Ordering Information

Testing the background noise at different pulse frequencies

When the pulse frequency is set to 18kHz, the background noise signal is clean, with no abnormal frequencies.

When the pulse frequency is set to 14kHz, the background noise signal is clean, with no abnormal frequencies.

When the pulse frequency is set to 12kHz, the background noise signal is clean, with no abnormal frequencies.

When the pulse frequency is set to 6kHz, the background noise signal is clean, with no abnormal frequencies.