Effects of Turnaround Command (TAC) on SGLS C/No and SNR performance

Dynamic Link from Liftoff to Final Orbital Insertion for a MEO Space Vehicle

“…From the end of LOS to NASA TDRSS at geosynchronous orbit, the telemetry link is a BPSK or QPSK (telemetry + data) which is sent from LV to TDRSS to be relayed to White Sands or Goddard ground station (WSGT/GRGT), as shown in the second right half of the Figure 3 and in more link details in Table 1. 3. For the third link after SV payload separation, when the satellite or SV starts its transfer orbit, the tracking link from the SV payload (or bus) to an AFSCN ground station will be in SGLS, Unified S-Band (USB), or a NSGLS waveform as described in more detail in [3,4]. For a more secure tracking, SV normally will be using SGLS link for tracking as described in [4], with a MEO satellite in Table 2 as an example.…”

“…For the third link after SV payload separation, when the satellite or SV starts its transfer orbit, the tracking link from the SV payload (or bus) to an AFSCN ground station will be in SGLS, Unified S-Band (USB), or a NSGLS waveform as described in more detail in [3,4]. For a more secure tracking, SV normally will be using SGLS link for tracking as described in [4], with a MEO satellite in Table 2 as an example. A commercial and less secure SV launch may use USB or NSGLS for SV tracking instead of using SGLS waveform.…”

“…For many SVs, we are interested in their uplink and downlink services. Table 2 shows an example, taken from an IEEE paper [4]. This is the standard link budget, where the ground station is an AFSCN [3] remote tracking station (RTS) using SGLS waveform [3,4].…”

“…Table 2 shows an example, taken from an IEEE paper [4]. This is the standard link budget, where the ground station is an AFSCN [3] remote tracking station (RTS) using SGLS waveform [3,4]. The waveform is described in an AFSCN interface control document (ICD) [3] and is implemented in DLA, although other waveforms can be readily incorporated.…”

“…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.…”