Previous satellite telemetry, tracking, and command (TT&C) link analyses [Ref 1, 4] for Space Ground Link Subsystem (SGLS) considered C/No and SNR (or Eb/N0), without including the effects of command turnaround noises. This paper analyzes SGLS services that include the Turnaround Command (TAC) intermodulation (IM) noises in addition to the regular thermal noise. The SGLS pseudorandom noise (PRN) ranging signals use a 500 kHz clock, which is a component (C1) of 1 Mcps PRN long ranging codes (C1, x, a, b, and c codes). Satellite test data shows that running a PRN ranging test with a 500 kHz clock is an acceptable approximation for the PRN case. The difference between PRN and 500 kHz clock ranging is small (same residual carriers of C= −40 dBm for PRN and 500 kHz clock ranging in Figures 1 and 2). This paper shows that the TAC robs power from SGLS signals, degrading their C/No or SNR and link performances. Also test data (Figure 2) is used to show that the TAC IM noises are as predicted by theories in the Appendix, and that they will reduce SGLS C/No and degrade the carrier and ranging acquisition performances. Luckily these TAC IM noises will not affect carrier and ranging tracking performances or telemetry demodulation, because these IM noises are outside of the narrow tracking or detection bandwidths.


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    Title :

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


    Contributors:


    Publication date :

    2018-03-01


    Size :

    654599 byte




    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English



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