Citation
Abstract
This article provides details on a comparison performed on calculated atmospheric effects on signal propagation using different methods for the Deep Space Network (DSN) and two Near Earth Network (NEN) sites commonly used in telecommunications link budgets. Atmospheric attenuation and scintillation fading are two of the many contributors that need to be taken into account in such link budgets between transmitter and receiver. Although atmospheric noise temperature increase is another contributor (at the receiver), it is well related to atmospheric attenuation through appropriate model equations. Telecommunication engineers working NEN link budgets make use of data and models obtained from the International Telecommunication Union (ITU) in order to estimate atmospheric effects. Such effects include atmospheric attenuation (gaseous, rain, and cloud), atmospheric noise temperature contribution, and scintillation. Because most NEN links usually operate at very high margins, uncertainties in the ITU models were not much of a concern in the past as they tended to be conservative, in comparison to links of the DSN that operate at low margins and thus require more accurate statistics on atmospheric effects. Such statistics for the DSN links make use of brightness temperature measurements from multiyear water vapor radiometer (WVR) data from instruments operating at the DSN sites. Atmospheric attenuation statistics derived from WVR data are well documented and are published by the DSN. Thus, the DSN sites make a good testbed in which to cross-compare atmospheric loss statistics with those derived from ITU data and models.
Details
- Volume
- 42-199
- Published
- November 15, 2014
- Pages
- 1–24
- File Size
- 377.1 KB