Research On The Effect Of Point Ahead Angle On The Performance Of Intersatellite Optical Communication System

Inter-satellite optical communication is the key point to complete the link of space and ground.Compared with inter-satellite microwave communication,the advantages of inter-satellite laser communication includes large communication capacity,great confidentiality,strong anti-electromagnetic interference ability,small equipment size,light weight,low power consumption and no need for radio frequency use license.Since the success of the first inter-satellite laser communication experiment,cooperation in the commercial field has begun.It is necessary for the terminal equipment equipped with a specific pointing,acquiring and tracking system to ensure the successful establishing the links that adopting laser as the mode of carrying link information.Compared with the development of optoelectronic components and the streamlined research of on-board terminals,the function of point ahead equipment in the PAT system is relatively simple,and its development is slightly insufficient.This paper bases on the purpose of streamlining the on-board terminals and proposes the way that using the large angle beam instead of point ahead equipment to compensate the deviation angle.First of all,this paper investigates the development of inter-satellite optical communication and point ahead equipment at home and abroad,introduces the purpose and working mode of the point ahead equipment,and also explains the pointing and acquiring and tracking's process.Then,this paper derives the expression of the point ahead angle based on the six basic elements Firstly,through simulation,the change of the point ahead angle of the GEO-LEO link with different orbital inclination angles is calculated when the orbital height of the LEO satellite is 500 km.Then the article simulates the inter-satellite links of different orbital heights and different orbital inclinations,and analyzes the maximum value of the point ahead angle in the GEO-LEO inter-satellite link.This paper establishes an inter-satellite cooperated tracking model with point ahead deviation.Then it analyzes the maximum pointing deviation by parameters such as detector angle measurement error and system compensation ability,and obtains the maximum pointing deviation and the maximum point ahead deviation that the system can withstand during the tracking phase.This paper conducts theoretical and simulation studies on the communication performance of inter-satellite laser links.By analyzing the parameters such as the average bit error rate,channel capacity and outage probability,the maximum point ahead error that the inter-satellite laser link can withstand is obtained when given the communication requirements of the system.Then the influence of the change of the point ahead angle on the communication time of the inter-satellite link is obtained.The conclusions of this paper have certain significance for the research of miniaturized terminals.It also provides some theoretical research on the terminal link when the point ahead equipment fails.