**Abstract**

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 cone angle geometry, and dynamic link budget.

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

## **1. Introduction**

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

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

payload (PL) separation from LV, using LV, to Tracking and Data Relay Satellite System (TDRSS) [1] satellite link, which is also called beyond line of sight (BLOS) link. A third SV tracking, after SV payload separation from LV, is a tracking link between SV and a ground station (GS). This third SV tracking is now added in this chapter.

The tracking link used from liftoff to the end of LOS uses a UHF noncoherent FSK signal for command and a digital FM or BPSK for tracking telemetry link as described in detail in [2]. From the end of LOS to BLOS, the tracking telemetry link is usually a BPSK or QPSK signal, using a NASA Tracking Data Relay Satellite System to relay tracking data from the LV to White Sands or Goddard ground station (WSGT/GRGT) and finally routing it to other user ground stations. After SV payload separation and orbital insertion, the SV tracking link to an Air Force Satellite Control Network (AFSCN) ground station [3] will use Space-to-Ground Link Subsystem (SGLS) or a non-SGLS (NSGLS) waveform described in [3, 4] and in Section 3 for tracking signals along the trajectory. In the following pages, supporting link analyses for the two LV and one SV tracking stages will be presented.
