This system measures the returned signal strength and Voltage Standing Wave Ratio (VSWR) of the pulse signal to judge the working statue of the LCX. The maximum test length of a single test unit is more than 2 kilometers, and the accuracy of fault location is better than 5 meters. The hardware design of the system is based on Software Defined Radio platform (SDR), and the algorithm is based on FPGA. The highlights of this systems are:

1. Advanced design concepts
The system adopts pulse compression technology, which combines the best characteristics of traditional pulse and FM continuous wave radar system, to achieve the integration of long detection distance and high precision fault locating. This system also integrated fault recognition and locating.

2. The design of the device is highly simplified, easy to maintain and has high stability.
The system uses SDR (software defined radio) technology to design the hardware system, greatly simplifies hardware design and improves reliability. Upgrades, operation and maintenance are mostly done by software, which greatly improves work efficiency and reduces maintenance workload. The circuit of FPGA is a “hardware programming” circuit. The traditional Processor-based systems often contain multiple abstraction layers, which can plan tasks and share resources among multiple processes. The driver layer controls hardware resources, while the operating system manages memory and processor resources. For any given processor core, only one instruction can be executed at a time, and processor-based systems are at risk of resources being taking over. However, without operating system, SDR is a real parallel execution and deterministic hardware dedicated to each task can greatly increase the stability.

3. Low transmission capacity, utilization of existing networks and lower cost.
With the powerful computing power of the FPGA, which surpasses the capability of digital signal processor (DSP), fault judgment is completed in the test unit. The test unit only needs to send out signals when the fault occurs or being checked. The transmission volume is much lower than that of the traditional background judgment system. The existing optical network can be used for transmission which could reduce the cost.

4. The software system is based on the Linux operating system, which has a strong possibility of secondary development. It can integrate the existing management platform or expand the software functions in accordance to the user’s requirement.