Citation
Abstract
The next generation of space very long baseline (SVLBI) missions will require a minimum downlink data rate of 1.024 Gb/s, and even more advanced missions propose to utilize 8.196 Gb/s. These high data rates place new demands on downlink spectrum resources and implementation technologies, especially for the space research Ka-band frequency allocation of 37 to 38 GHz which is only 1 GHz wide. To meet this challenge, it becomes necessary to make use of simultaneous left-hand circular and right-hand circular polarized carriers, as well as various forms of bandwidth compressive modulation, along with modulation pulse shaping. Consideration is also given to the National Telecommunications and Information Administration regulations regarding out-of-band spectrum emissions. Other serious problems for future SVLI missions are restrictions on spacecraft effective isotropic radiated power and the cost of attaining the necessary G/T for ground tracking stations. Accordingly, special attention is given to specifying the allowable maximum bit-error rate, along with a statistical downlink design philosophy regarding the three most important temporal parameters of communications slant range, ground antenna elevation, and weather conditions. Additionally, it is proposed that separate data and timing transfer carriers be employed as a means for achieving ground tracking station implementation and operating economies.
Keywords
Details
- Volume
- 42-149
- Published
- May 15, 2002
- Pages
- 1–26
- File Size
- 336.7 KB