urn:nasa:pds:context:instrument:dsn.media 1.0 1.13.0.0 Product_Context 2020-05-10 1.0 Initial version of the DSN Median Calibration Subsystem context product. urn:nasa:pds:radiosci.documentation:dsn.810-005 instrument_to_document This is the DSN Telecommunications Link Design Handbook. The reference is to a PDS Collection. Each member product in the Collection comprises several modules -- sometimes separate files, sometimes wrapped together into a single file, depending on the Handbook version included in the Collection. Modules are added, removed, and/or updated as needed. Each version of the Handbook (each member product of the Collection) contains all modules that were current as of the publication date. Module 303 describes equipment used by the DSN to obtain data from which correction factors can be determined for media effects that limit accuracy in radio tracking of spacecraft. The data are forwarded from each Deep Space Communications Complex to the Network Operations Control Center at JPL for processing, distribution, and archive. Mannucci, A. J., B. D. Wilson, D. N. Yuan, C. H. Ho, U. J. Lindqwister, and T.F. Runge, A global mapping technique for GPS-derived ionospheric total electron content measurements, Radio Science, 33, 3, 565-582, 1982. This paper describes a technique for retrieving global distribution of vertical total electron content (TEC) from GPS-based measurements. TEC is interpolated within triangular tiles that tessellate the ionosphere, modeled as a thin spherical shell. High spatial resolution can be achieved using gradient values and polynomial fitting. Keihm, S. J., Water vapor radiometer measurements of the tropospheric delay fluctuations at Goldstone over a full year, TDA Progress Report, 42-122, 1-11, Pasadena: Jet Propulsion Laboratory, 1995. The report describes the performance of the DSN Water Vapor Radiometers (WVR), used to estimate radio path delay in the troposphere. Keihm, S. J., A. Tanner, and H. Rosenberger, Measurements and calibration of tropospheric delay at Goldstone from the Cassini media calibration system, IPN Progress Report 42-158, Pasadena: Jet Propulsion Laboratory, 2004. The report describes the performance of the Advanced Media Calibration (AMC) system developed to support Cassini radio science. Asmar, S. W., J. W. Armstrong, L. Iess, and P. Tortora, Spacecraft Doppler Tracking: Noise Budget and Accuracy Achievable in Precision Radio Science Observations, Radio Science, 40, RS2001, doi:10.1029/2004RS003101, 2005. The paper discusses noise in Doppler tracking of deep space probes and provides a detailed noise model for Doppler radio science experiments. Current technology allows velocity measurements to better than 1 micron per second when data are averaged over 1000 seconds. Examples from Cassini are included. Applications of the noise model to experiment planning are considered, and the authors discuss the prospects for significant sensitivity improvements. Deep Space Station Media Calibration Subsystem Radio Science The Media Calibration Subsystem (DMD) provides three types of data: (1) Global Positioning System (GPS) data consisting of L-band carrier phase and group delay of GPS satellite signals, ephemeris, and almanac data for the GPS satellites; (2) Weather data, including temperature, barometric pressure, relative humidity, precipitation rate, total precipitation, wind speed, and wind direction. (3) Data from fixed Water Vapor Radiometers (WVR), which measure emission by water vapor in the atmosphere. The WVR is part of normal DSN operations. At selected DSN stations, an advanced version (AWVR) measures emissions at 20.7 and 31.4 GHz along the line of sight to a spacecraft being tracked. The AWVR is remotely operated for the DSN by the JPL Radar and Radio Science Systems Group (RRSSG) in Pasadena; it is an element of a larger Advanced Media Calibration (AMC) system. The AMC also includes a microwave temperature profiler and a sensitive digital barometer. The AMC is capable of measuring the tropospheric relative frequency shift under summer conditions with a precision of better than 1e-14.