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Optimum receiver bandwidth for a modulated pulsed signal propagating through a dispersive medium is obtained by minimizing the stretching of the envelope. Bandwidth is shown to be strongly dependent on modulation and its dependence is discussed in detail.
The main interest has been in the study of the initial build-up of the signal, pulse compression, distortion, etc., in detail so as to ascertain the effect of propagation characteristics of the media. However, the modification of the pulse by the dispersive nature of the receiver channel does not appear to have been analysed in detail.
Wait (1969) has suggested that there is an optimum receiver bandwidth for a given amplitude modulated signal and a specified propagation channel which would minimize the stretching of the received pulse envelope. [ABSTRACT FROM AUTHOR]

The non-linear propagation of VLF waves in weakly as well as in strongly ionized plasmas has been investigated by solving the Boltzmann transfer equation for charged particle distributions. The wave equation for the electric field has been solved in W.K.B. approximation. A particular reference has been given for ionospheric propagation. The non-linear effects are shown to be of importance even for moderately strong electric fields. The effect of the motion of ions has been found to decrease the non-linearity.
This paper presents an analysis of the non-linear propagation of VLF and ELF waves in magnetoplasmas, taking into account the motion of ions. It has been assumed that only the electrons are responsible for the non-linear phenomenon. This is a valid assumption because of the fact that the mass of the electron is very small as compared to the mass of the ion ; therefore, the energy transfer to other heavier species and to the surroundings is much less in the earlier case than in the latter. [ABSTRACT FROM AUTHOR]

Using hydrodynamical methods, the propagation of pressure waves in a non-isothermal fully ionized gas has been considered for a situation where collision between various particles cannot be ignored and the following pressure equation has been obtained: p/t + p/t - (V[SUB 3[SUP2]] + V[SUB l[SUP2]]) /tp + [SUB E[SUP2]] p/t - V[SUB l[SUP2]] /t p -[SUB e[SUP2]] V[SUB l[SUP2]]p + V[SUB i[SUP2]]V[SUB e[SUP2]]p = 0. where V[SUB i[SUP2]], V[SUB e[SUP2]] and V[SUB l[SUP2]] represent respectively kT/m, kT/m and k(T + T)/m and other symbols have their usual meaning.
This gives the following dispersion relation for a sinusoidal sound wave V[SUB i[SUP2]]V[SUB e[SUP2]]k - [ V[SUB e[SUP2]] - ([SUB e[SUP2]] - i) V[SUB l[SUP2]] ]k + [ - ([SUB e[SUP2]] - i)] = 0.
The phase velocity of propagation and attenuation of the sound waves have been discussed in the low frequency and high frequency region and it has been shown that low frequency sound waves travel with a velocity V, while high frequency sound waves are carried by ions and electrons with velocities V and V respectively.
Because of the difference in the masses of the ions and electrons, an electrostatic field of the same frequency as that of the sound is created during the propagation of sound waves. This field is given by: E = e/l/kTV/(V[SUB l[SUP2]]/V - 1) p and it is appreciable only at high frequencies where V < V. [ABSTRACT FROM AUTHOR]

Coupled wave equations have been developed for the propagation of electromagnetic, electron acoustic and ion acoustic waves in a homogeneous, warm magnetoplasma employing the linearized two-fluid continuum theory of partially ionized plasma dynamics. For the purpose of this study propagation is considered in a plane transverse to the static magnetic field. Coefficients occurring in the dispersion relation have been calculated for two-component electron-ion hydrogen magnetoplasma over a wide frequency spectrum and these are used to study the dispersion relation in various frequency ranges. It is observed that the modified ion plasma mode propagates in the entire range of the frequency spectrum but the electromagnetic mode, ordinary as well as extraordinary, and the electron-plasma mode propagate only in the range higher than the electron plasma frequency. [ABSTRACT FROM AUTHOR]