An analytical method, called the “multiple filter technique,” is shown to be a fast and efficient means of studying multi-mode dispersed signals. Amplitudes and phases, as functions of period and velocity, are determined from the output of a set of narrow-band digital filters. The group velocities and other dispersion parameters determined by this technique are concordant with theoretical values when the method is tested with synthetic seismograms. It can recover broader portions of the dispersion present in ordinary seismic recordings compared to the classical peak and trough method. A simple diagnostic diagram is introduced in order to study the time and frequency resolution permitted by this analytic technique.

In dispersive media the phase velocity, group velocity, energy velocity, signal velocity, relativistic velocity constant, and ratio-of-units velocity are usually not useful concepts for wave packets. The centrovelocity has been suggested as a measure which overcomes many of the objections to the first six. We describe yet another, based on the cross-correlation of the original and received wave packets, which is shown to be useful in time-of-flight measurements in weakly and strongly dispersive media; absorption and amplification are readily accommodated. Applications for specific examples of wave packets in magnetoplasmas are presented.

A detailed description and analysis are presented of the psychological stress evaluator (PSE), an instrument purported to measure accurately and to portray graphically differential levels of stress in human speech. In addition, two studies are presented that attempt to validate this instrument against better known measures of stress or A-state anxiety. The PSE measures were compared with heart rate and State Trait Anxiety Inventory (STAI) A-state scores obtained under conditions where the level of stress was experimentally manipulated through threat of shock or the presentation of taboo words. The first study revealed that PSE, STAI, and heart rate measures accurately reflect different levels of stress and are significantly correlated with one another. The second study failed to replicate the validity of the PSE. This failure to replicate is attributed to lower levels of induced stress and a reduction in baseline measures of stress.

Tampa, Florida (28°N, 82.5°W), has about 90 thunderstorm days per year, almost all in summer. These convective events tend to occur in afternoon or early evening. This paper presents results of 19‐GHz downlink rain attenuation diversity studies in Tampa involving site separations of 11, 16, and 20 km and reception at high elevation angle (about 57°), over a period of 29 months, including three rainy seasons. Almost identical long‐term performance with the two larger spacings indicates that for separations above about 15 km, diversity improvement was not sensitive to baseline orientation or length. During a fourth rainy season, using the remaining 29‐GHz beacon, diversity improvement with the 16‐km pair was similar to that predicted by scaling the 19‐GHz results of the previous seasons. Also discussed are the type of attenuation distributions and typical fade durations to be found under persistent convective conditions. For rain climates like Tampa's, site diversity in some form will be required for high‐reliability SHF satellite links. The diversity data may be helpful in designing schemes for resource sharing among numbers of links.