Engineering topics

Evans, J. M., Jr.

Publications and source records attributed to Evans, J. M., Jr..

3 records

NASA NTRS1978

System and method for tracking a signal source

A system for tracking moving signal sources is disclosed which is particularly adaptable for use in tracking stage performers. A miniature transmitter is attached to the person or object to be tracked and emits a detectable signal of a predetermined frequency. A plurality of detectors positioned in a preset pattern sense the signal and supply output information to a phase detector which applies signals representing the angular orientation of the transmitter to a computer. The computer provides command signals to a servo network which drives a device such as a motor driven mirror reflecting the beam of a spotlight, to track the moving transmitter.

Mogavero, L. N.↗

NASA NTRS1976

Tracking system for moving subjects

Electronic system automatically focuses camera or spotlight on moving object. Subject is equipped with miniature ultrasonic or radio transmitter; its signal is picked up by two or more detectors, is phase detected and fed into computer which determines position of subject and sends command signals to servo for camera or spotlight.

Mogavero, L. N.↗

NASA NTRS1972

Determination of Van der Waals broadening at temperatures of astrophysical interest.

Discussion of the results of experiments analyzing the widths of shock-excited emission lines at temperatures of about 5000 K. The width of two neutral silicon lines (4102 and 5948 A) were measured as broadened by argon, and the shift of one of these lines (4102 A) was determined. Likewise, the width one of the lines of cesium (4593 A) was measured as broadened by argon and neon. These data are compared with other experimental data to determine the temperature dependence of the broadening. Significant disagreements with simple theory are found, the experimental values of the widths being larger than the theoretical values by factors of 1.5-2.

Evans, J. M., Jr.↗