Measurements of phase stability over a low-level tropospheric path

Abstract

A knowl edge of the sta tistics of a tmosphere-induced v aria t ions in t he p ha se of Lhe received signal (i. e., va riations in electrical path length) is esse ntia l in eva luaLing ('he r elia bility of a ny sy ste m using radio wa ves for measur ing dista nce a nd/or ve loei Ly. This p ap er d escribes a n ana lysis of phase varia t ion s measured at 9,400 m egacycles p el' seco nd over a 9.4mile path near Boulder, Colora do, during a 40-hoLll' period in SepLe rnber 1958. The power sp ectral density of these variations is shown to be a pproximately prop ort ion a l t o j-2 .8 over a wide range of fr eque nci es t lu'o ughou t the p eriod of recordin g. The long-term phase v a riation s are closely correlated ,,'ith atmospheric refrac tivi ty measure ments ma de at the path term inals.

Radio-wave scattering by tropospheric irregularities

“…Equation (2. 3.1 ) may b e inverted to establish the spectrum which corresponds to each of the correlation functions discussed earlier.…”

“…A more difficul t problem is en countered with the assumption of tationarity. Ther e now seems to be experim ental evidence [3] that the dielectric variations eith er: (1) do not form a stationary process; or (2) that th er e is a gr eat deal of power in the lowfrequen cy part of the spectrum of ~f , which appears as trend when viewed over a short span of time or space. Both explanations are probably partially correct, with a rapidly fading stationary process sup erimposed on long-period (diurnal, seasonal) harmonic components.…”

Phase fluctuation statistics

“…If 10 is equal to or greater than the path length L , the results observed by Thompson and Janes [1959 ], Herbstreit and Thompson [1959];and Deam and Fannin [1955] are easily seen to be related to the dielectric constant fluctuations associated with air mass motions. Simultaneous radio phase measurements taken by Herbstreit and Deam on 9,350 Mc/s and 1,040 Mc/s yield rms phase variations which are almost directly proportional to the frequency ratio, 12.6° at 9,350 Mc/s and 1.09° at 1,040 Mc/s.…”

Preliminary Analysis of a Proposed High-Stability Frequency Standard Distribution System

“…Thompson and Janes [15] reported detailed measurements of both long-and short-term tropospheric phase path instabilities at 9.4 GHz over a 15 km long path near Boulder, Colorado. Although the path had a low elevation angle, the measured spectral shapes are probably applicable to the transatmospheric path.…”