Satellite Systems Modeling Simulation and Analysis

**Chapter 8**

**Abstract**

**1. Introduction**

**163**

Dynamic Link from Liftoff

During the entire launch sequences from liftoff to final orbital insertion of a space vehicle (SV), adequate link requirements are to be maintained for telemetry, tracking, and command (TT&C) for uplink and downlink services, from launch vehicle (LV) and SV to ground stations (GS). A successful space vehicle launch required adequate link coverage with good radio frequency (RF) performance. The chapter is an extension of the IEEE/Aerospace Conference 2019 paper entitled Dynamic Link Analysis and Application for a MEO Space Vehicle published by the authors. The emphasis in this chapter is on the addition of the three distinctively different tracking waveforms and their associated links, used from liftoff to final orbital insertion. This chapter will describe the three required dynamic link analyses (DLA) to cover (a) the LV link from liftoff to its end of line of sight (LOS), (b) the LV link from LOS to Tracking and Data Relay Satellite System (TDRSS) at beyond line of sight (BLOS), and (c) the final tracking link using Space-to-Ground Link Subsystem (SGLS) or non-SGLS (NSGLS) link for the earliest or best separation time of the SV from the LV. The chapter discusses the concept of the dynamic link analysis, SV antenna switching schedule, recommended SV separation time, as well as the performance for different launch scenarios within the 24-h launch window. Topics include antenna patterns, launch trajectories, elevation angle and clock and

Recently, there was an interest to extend the present dynamic link analyses (DLA) beyond the early launch period to cover the period after the space vehicle (SV) separation from launch vehicle (LV), which includes both booster and second stage engine. The dynamic link from liftoff to final orbital insertion considers both geometric (visibility coverage) and radiometric (link margins for all downlink and uplink services) adequacy in the three launch stages. The purpose of the dynamic link study for the launch is to provide the earliest and accurate time for final SV separation and orbital insertion as compared to previous method which only relied

The present DLA typically covers only two stages of LV tracking, including (a) liftoff to the end of LOS link and (b) the end of LOS to a period before SV

to Final Orbital Insertion

for a MEO Space Vehicle

*Jack K. Kreng and Gleason Q. Chen*

cone angle geometry, and dynamic link budget.

**Keywords:** wide band communications, satellite tracking

on visibility tracking coverage to the end of line of sight (LOS).

### **Chapter 8**
