KEYWORDS: Laser communications, Laser communication terminals, Acquisition tracking and pointing, Data transmission, Control systems, Satellite communications
Space laser communication has the advantages of fast transmission rate, strong anti-interference ability and high confidentiality, and is the future development trend of high-speed data transmission in space. The laser beam dispersion angle is small, and the field of view of space environment reception is limited, so it is necessary to track the beam stably in order to realize high-speed data communication. However, due to the influence of certain environmental factors or internal factors of the terminal, the tracking process will inevitably break the chain, which can not ensure stable data communication. Acquisition and tracking is a fast servo control system. It is difficult to diagnose the cause of chain breakage by viewing the telemetry on the bus to capture the state at the moment of chain breakage after the chain is built by on-rail laser communication. Aiming at this problem, this paper proposes a diagnostic method of broken chain for space laser communication, so that the relevant data can be locked at the moment of broken chain after the satellite enters the orbit and the data can be transmitted back to the ground. Then the professionals can analyze the cause of the broken chain and find the corresponding solutions to modify it in the orbit.
Laser spot center detection is demanded in many applications. The common algorithms for laser spot center detection such as centroid and Hough transform method have poor anti-interference ability and low detection accuracy in the condition of strong background noise. In this paper, firstly, the median filtering was used to remove the noise while preserving the edge details of the image. Secondly, the binarization of the laser facula image was carried out to extract target image from background. Then the morphological filtering was performed to eliminate the noise points inside and outside the spot. At last, the edge of pretreated facula image was extracted and the laser spot center was obtained by using the circle fitting method. In the foundation of the circle fitting algorithm, the improved algorithm added median filtering, morphological filtering and other processing methods. This method could effectively filter background noise through theoretical analysis and experimental verification, which enhanced the anti-interference ability of laser spot center detection and also improved the detection accuracy.
The hardware-in-the-loop simulation system, which provides a precise, controllable and repeatable test conditions, is an important part of the development of the semi-active laser (SAL) guided weapons. In this paper, laser energy chain characteristics were studied, which provides a theoretical foundation for the SAL guidance technology and the hardware-in-the-loop simulation system. Firstly, a simplified equation was proposed to adjust the radar equation according to the principles of the hardware-in-the-loop simulation system. Secondly, a theoretical model and calculation method were given about the energy chain characteristics based on the hardware-in-the-loop simulation system. We then studied the reflection characteristics of target and the distance between the missile and target with major factors such as the weather factors. Finally, the accuracy of modeling was verified by experiment as the values measured experimentally generally follow the theoretical results from the model. And experimental results revealed that ratio of attenuation of the laser energy exhibited a non-linear change vs. pulse number, which were in accord with the actual condition.
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