Propagation effects on radio range and noise in earth‐space telecommunications

Abstract

Deep‐space missions and radio navigation satellite operations place high requirements upon the precision of range and Doppler frequency measurements and may be sensitive to even small increases in radio noise. For paths to geostationary satellites and beyond, the excess range delay due to the ionosphere and plasmasphere is proportional to the total electron content along the path and inversely proportional to frequency squared. The delay for a one‐way path is about 8 m for a total electron content of 1018 el/m2 at a frequency of 2.2 GHz. The one‐way excess range delay due to the dry air of the troposphere on earth‐satellite paths is typically of the order of a few meters and is dependent only on surface pressure for a given elevation angle. The delay due to water vapor, a few tens of centimeters, is responsible for most of the temporal variation in the range delay for clear air. In the navigation of Voyager spacecraft, where two‐way range measurements are made, range is determined with a precision of better than 3 m by the National Aeronautics and Space Administration/Jet Propulsion Laboratory Deep Space Network, made up of stations in Goldstone, California, Madrid, Spain, and Canberra, Australia. System noise temperatures for the Deep Space Network are typically 20–30 K. For such low‐noise systems and for attenuation values up to about 10 dB, the increase in sky noise due to rain and clouds degrades the received signal‐to‐noise ratio more than does the reduction in signal level due to attenuation. Clouds as well as rain contribute significantly to attenuation and sky noise, especially for frequencies greater than 10 GHz. Doppler frequency fluctuations due to the interplanetary plasma can be reduced by using higher frequencies (X or K band rather than S band, for example), but scintillation of tropospheric origin may then become the principal factor limiting the ability to detect gravitational waves.

Performance of Earth Troposphere Calibration Measurements With the Advanced Water Vapor Radiometer for the Juno Gravity Science Investigation

“…These signals propagate through several forms of media which introduce noise onto the signal, including Earth's troposphere and ionosphere (Flock et al., 1982), solar plasma (Armstrong, 1998), and the Io Plasma Torus (Phipps et al., 2017). Earth's ionosphere, solar plasma, and the Io Plasma Torus are dispersive noise sources, of which the magnitude of the noise is a function of the frequency.…”

Radio Techniques for Probing the Terrestrial Ionosphere

“…( 1.13) Another essential component of the system, the antenna, also can be analyzed using the noise temperature concept. (Flock et al 1982) thermal radiation from the earth's surface, man-made electrical noise, and even noise introduced by the antenna structure. 1.16.…”

“…The antenna noise temperature, TA' is due to reception of noise power through the main beams and sidelobes from a variety of sources, such as: the sun and other radio stars, terrestrial atmospheric effects, Antenna Une (Attenuator) Tsys T o Fig. These subjects are discussed in detail by Kraus (1966), Bell Telephone Laboratories (1982, Flock (1987), Flock et al (1982), and Spaulding and Washbum (1985). Idealized antenna and receiver for noise analysis.…”