ATMOSPHERIC ACOUSTIC PROPAGATION STUDIES.
Abstract
The mechanical and electronic design of an infrasonic system that can be used to continuously study atmospheric acoustic propagation is described. The source radiates about 30 watts at a frequency of 13 to 14 cycles per second. The frequency of the source can be controlled to within plus or minus .01% which enables studies of the signal doppler shifts and amplitude variations to be made. The receiver uses a phase lock detector to monitor the doppler shifts and to increase the sensitivity. Transmission studies to date have been made out to distances of 10 kilometers down wind. Large amplitude variations as a function of time are commonly observed, but the doppler shift variations are less pronounced. Some of the observed variations are correlated with surface wind variations, but at the longer ranges the conditions at higher elevations become more important. With some improvement in the noise discrimination it should be possible to study acoustic wave propagation into the trospheric jet stream. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1970
- Accession Number
- AD0709318
Entities
People
- Andrew Chung
- Lee W. Dean
- Theodore R. Madden
Organizations
- Massachusetts Institute of Technology