Citation
Abstract
Lower frequency telemetry bands are becoming more limited in bandwidth due to increased competition between flight projects and other entities. Higher frequency bands offer significantly more bandwidth and hence the prospect of much higher data return. Future or prospective flight projects considering higher frequency bands, such as Ka-band (32 GHz) for deep-space and K-band (26 GHz) for near-Earth telemetry links, are interested in past flight experience with available received data at these frequencies. Given that there is increased degradation due to the atmosphere at these higher frequencies, there is an effort to retrieve flight data of received signal strength to analyze performance under a variety of factors. This article reports on the analysis of over 11 million observations, collected between near mid-2017 and the beginning of 2020, of received signal strength of the Lunar Reconnaissance Orbiter (LRO) spacecraft. We analyzed these data to characterize link performance over a wide range of weather conditions, seasons, and as a function of elevation angle. Based on this analysis, we have confirmed the safety of using a 3 dB margin for preflight planning purposes. The results suggest that a 3 dB margin with respect to adverse conditions will ensure a ~98 to 99% data return under 95% weather conditions at 26 GHz, thus confirming the expectations from link budget predictions. The results of this study and a previous study suggest that this margin should be applicable for all elevation angles above 10 deg. Thus, missions that have sufficient power for their desired data rates may opt to use 10 deg as their minimum elevation angle. The limitations of this study include climate variability and observations that require removal of hotbody noise in order to perform an adequate cumulative distribution function (CDF) analysis. Flight projects may use other link margins depending upon available information, uncertainties of non-atmospheric link parameters, and mission phase.
Details
- Volume
- 42-222
- Published
- August 15, 2020
- Pages
- 1–15
- File Size
- 4.5 MB