Numerical simulation of ionospheric wave interaction experiments.

Ionospheric nonlinear wave interaction (cross modulation) experiments are conveniently and more accurately analyzed by using a computer-oriented simulation process resembling ray tracing in the height-time domain. Advantages of such a process over existing analytical methods are discussed, and typical experiments are simulated to illustrate its flexibility.The technique is modified to yield a numerical method for directly synthesizing D-region electron density and collision frequency profiles from experimental interaction measurements. Accuracy limitations inherent in the synthesis process raise· doubts about the utility of the basic experiment as an accurate D-region electron density probe.

Section: Representative Calculationsmentioning

confidence: 99%

“…A few representative results are given here; these and others are discussed in greater detail by Georges [1965]. · Unless otherwise specified, the experimental conditions which are simulated are as follows: figure 4.…”

Section: Representative Calculationsmentioning

confidence: 99%

A Numerical Method for Interpreting D‐Region Radio Pulse Interaction Measurements

Georges

1966

“…The solution of many of the problems in refining and optimizing this type of experiment and in the development of effective data reduction techniques depends ultimately on the formulation of a more comprehensive model of the interaction mechanism. This note summarizes a recent publication [Georges, 1965] which presents a simple method for simulating the interaction process on a digital computer. The technique is directly applicable to verticalincidence pulse interaction experiments based on the method of Fejer [1955], including cosmic noise interaction [Benson, 1962), phase interaction [Ferraro et al, 1963], and gyrointeraction [Smith, 1964].…”

Section: T M Georgesmentioning

confidence: 99%

Numerical Simulation of Ionospheric Wave Interaction Experiments (Digest of NBS Technical Note 325)

Georges

1966

The need for an improved ground‐based radio technique for probing the lower ionosphere has prompted a number of experiments based on nonlinear radio wave interaction (ionospheric cross modulation or Luxembourg Effect) [Fejer, 1955: Rumi and Little, 1958: Barrington and Thrane, 1962: Ferraro et al., 1963: Smith, 1964]. Their success as accurate and continuous D‐region probes has been somewhat limited by the need for much greater experimental accuracy and sensitivity and an efficient method for interpreting interaction data in terms of electron density and collision frequency profiles. The solution of many of the problems in refining and optimizing this type of experiment and in the development of effective data reduction techniques depends ultimately on the formulation of a more comprehensive model of the interaction mechanism. This note summarizes a recent publication [Georges, 1965] which presents a simple method for simulating the interaction process on a digital computer. The technique is directly applicable to verticalincidence pulse interaction experiments based on the method of Fejer [1955], including cosmic noise interaction [Benson, 1962], phase interaction [Ferraro et al., 1963], and gyrointeraction [Smith, 1964]. By avoiding the explicit formulation and solution of closedform expressions for the interaction effects, many of the limitations and approximations involved in analytical treatments are bypassed. The simulation of many different interaction experiments using various theoretical models yields estimates of the limits of applicability of the simplified analytical theory, and shows that it becomes a poorer approximation as experimental conditions necessary for improved accuracy and sensitivity are approached. The numerical method also provides a basis for the development of an effective technique for the synthesis of ionospheric profiles from interaction data.

Computer simulation and analysis of the Fejer gyrowave interaction experiment

Nath¹,

Setty²

1979

The gyrowave interaction experiment yields the impressed modulation as a function of time delay (meeting height) between the wanted and the disturbing radio frequency pulses. This is referred to as the Fejer curve. In this paper we compute the Fejer curves for the geomagnetic conditions of Delhi, using an exponential model of the D region ionization, temperature dependent energy relaxation factor G, a model collision frequency v of the Sen‐Wyller magnetoionic theory, and the standard wave interaction theory. The Fejer curves are then inverted to recover the electron density profile, thus completing the close circuit computation. In the process of inversion of the Fejer curve the D region is assumed to be isothermal, and the effect of this assumption is investigated. It is found that it is possible to recover the original electron density profile if the mean D region temperature is adopted.