Influence of data burst collision on transmission of AWS data through satellite

lkj & Lopkfyr ekSle dsanz ¼,-MCY;w- ,l-½ og iz.kkyh gS ftlesa losndksa ds lkFk ml {ks= dh mi iz.kkyh vkSj lapkj midj.k lEc) :Ik ls dk;Z djrs gSa tks Lopkfyr :Ik ls vkSj yxkrkj lgh le;kuqlkj ml LFkku dh ekSle dh fLFkfr;ksa dh eki djrs gSa rFkk ekSle foKku ds ekin.Mksa ds vuqlkj ?kaVkokj fy, x, izs{k.kksa dks dasnz ls tqM+s mixzg ds }kjk dsanzh; LVs’ku dks rhu ckj Lo;a fu/kkZfjr i)fr }kjk vxyk izs{k.k ysus ds iwoZ 60 feuV ds vUnj fu/kkZfjr 10&10 feuV ds vUrjky ij fcuk fdlh Øe ds vkHkklh ladsrksa dkss Hkstrs jgrs gSa A dHkh dHkh nks ;k vf/kd Lopkfyr ekSle dsanzksa ls vk¡dM+s ,d gh le; esa laizsf"kr gksus ij muds fefJzr gks tkus ds dkj.k ,- MCY;w- ,l- ds vk¡dM+s Bhd ls izkIr ugha gks ikrs gSa A eq[;r;k ,- MCY;w- ,l- ds vk¡dM+ksa dk lafeJ.k muds laizs"k.k ds le; vFkok laizs"k.k dh xfr latky esa ,- MCY;w- ,l- dh la[;k rFkk ,- MCY;w- ,l- ds vk¡dM+ksa ds lafeJ.k dh ek=k ij fuHkZj djrk gS A bl ’kks/k Ik= esa ,- MCY;w- ,l- ds vk¡dM+ksa ds mixzg ds ek/;e ls laizsf"kr vk¡dM+ksa ds lkFk vkil esa lafefJr gks tkus ls iM+us okys izHkko ds ckjs esa crk;k x;k gS A ” Automatic Weather Station (AWS) is a system consisting of sensors, associated field sub-systems and communication equipment, which automatically and continuously measure real time surface weather conditions and sends three times the hourly observed meteorological parameters to the central station through satellite link in a self timed pseudo random manner in its prescribed 10 minute time slot within the next 60 minutes before the next observation takes place. Loss of AWS data is due to collision of data burst transmitted simultaneously by any two or more AWS. Generally, the collision of AWS data burst depends upon the transmission time or transmission baud rate, number of AWS in a network and total number of bits in AWS data burst. This paper describes the influence of data burst collision on transmission of AWS data through satellite.

An Adaptive Topology Optimization Strategy for GNSS Inter-satellite Network

Inter satellite link (ISL) is an effective way for the global navigation satellite system (GNSS) to reduce its dependence on ground infrastructure, which guarantees constellation orbit determination and satellite communication. When the number of onboard Ka-band ISL antennas is less than that of visible satellites, the inter-satellite link assignment of GNSS causes a problem. For the problem of inter-satellite link scheduling, considering that the result of the allocated link has a feedback effect on the subsequent link assignment as a priori knowledge, an adaptive topology optimization algorithm based on signed variance (ABSV) is proposed. In order to meet the requirements of communication and ranging performance, the time slot is divided into a communication time slot and a ranging time slot. Taking the waiting delay time of satellite communication and PDOP as measurement indexes, the proposed strategy is simulated for 10080 min. The results show that the ranging performance of this strategy is better than other recently published methods, which verifies the effectiveness of signed variance for adaptive link planning and is also beneficial to the survivability of constellation.

An Adaptive Topology Optimization Strategy for GNSS Inter-satellite Network

Inter satellite link (ISL) is an effective way for the global navigation satellite system (GNSS) to reduce its dependence on ground infrastructure, which guarantees constellation orbit determination and satellite communication. When the number of onboard Ka-band ISL antennas is less than that of visible satellites, the inter-satellite link assignment of GNSS causes a problem. For the problem of inter-satellite link scheduling, considering that the result of the allocated link has a feedback effect on the subsequent link assignment as a priori knowledge, an adaptive topology optimization algorithm based on signed variance (ABSV) is proposed. In order to meet the requirements of communication and ranging performance, the time slot is divided into a communication time slot and a ranging time slot. Taking the waiting delay time of satellite communication and PDOP as measurement indexes, the proposed strategy is simulated for 10080 min. The results show that the ranging performance of this strategy is better than other recently published methods, which verifies the effectiveness of signed variance for adaptive link planning and is also beneficial to the survivability of constellation.

A Method for Calculating Dynamic Parameters of Intersatellite Link Signals

Aiming at the complex dynamic changes of inter-satellite link signals, this paper proposes a low-complexity method to calculate dynamic parameters of inter-satellite link signals so as to simulate inter-satellite link signals with complex dynamic characteristics. Based on the precise ephemeris, the algorithm is used to calculate the transmission delay and Doppler frequency of the signals in an inertial frame of reference by using iteration and interpolation. The calculation result is compared with the result obtained by using the simulation software of the global navigation system. It is found that the error of the transmission delay is at the nanosecond level and the error of Doppler frequency is at the Hertzian level. Therefore, the dynamic signal simulation accuracy can meet the requirements of load testing and verification of inter-satellite links. The algorithm is simple to implement.

Juventas Cubesat for the Hera mision

<p>The Juventas CubeSat, will be delivered to the Didymos binary asteroid system by ESA's Hera mission within the context of the Asteroid Impact and Deflection Assessment (AIDA) international collaboration. AIDA is a technology demonstration of the kinetic impactor concept to deflect a small asteroid and to characterize its physical properties. Due to launch in 2024, Hera would travel to the binary asteroid system Didymos. It will explore the binary asteroid and the crater formed by the kinetic impact the NASA’s Double Asteroid Redirection Test (DART). HERA will carry two 6U CubeSats, one of which is the Juventas CubeSat developed by GomSpace Luxembourg with the Royal Observatory of Belgium as principal investigator. The spacecraft will attempt to characterize the internal structure of Didymos’ secondary body, Dimorphos, over a period of roughly 2 months using a low-frequency radar, JuRa. During this period, Juventas will also perform radio science measurements using its Inter-Satellite-Link to characterize the mass and mass distribution of Dimorphos. Afterwards, Juventas will attempt to land on Dimorphos, during which the spacecraft is expected to perform several bounces. Once landed, Juventas will use its gravimeter GRASS to obtain measurements of the surface acceleration on Dimorphos for a nominal duration of two orbits. Through the monitoring of dynamics for landing and bouncing impacts as well as measurements from the GRASS gravimeter payload while on the surface, Juventas will determine surface mechanical properties and provide further information on subsurface structure and dynamical properties of Dimorphos.</p>

Evaluating Unavailability Algorithm of the Satellite Link Based on the Rain Factor, Taking into Account the Requirements for Bandwidth, Reliability and Limitation of the Frequency and Energy Resource

The article presents an algorithm for evaluating the indicator of unavailability for the rain factor of satellite radio link sections, taking into account the requirements for throughput, reliability and limitation of the frequency and energy resource. In contrast to the existing approaches, the proposed problem is based on an analytical expression, which reduces the computational complexity under acceptable constraints.