ACOUSTIC PHASED ARRAYS FOR THE DETECTION OF NUCLEAR BURSTS IN THE ATMOSPHERE
Abstract
An acoustic phased array serves to improve both the signal-to- turbulent-noise ratio and the signal-to-acoustic-noise ratio. The improvement in acoustic signal-to-noise ratio is, for isotropic noise, the array gain--which is calculable and is discussed herein. The improvement in the turbulent signal-to- noise ratio cannot be calculated, in view of the unknown correlation of noise in single sensors. However, it is thought likely that this improvement will be at least as much as the acoustic improvement--especially at the higher frequencies of greatest interest for small yields. This Memorandum considers, for simple unshaded square plane arrays, the dependence of array gain upon frequency, azimuth, size of array, number of sensors in the array, and uncertainty in the local velocity of sound. It is shown that an array of 16 sensors at the lattice points of a 1/2 x 1/2 mile square offers a frequency-dependent gain which rises to nearly 10 db at 0.5 cps for any azimuth and for any sound speed in the range of 1000 to 1200 ft/sec. Such an array appears to be suitable for the detection of acoustic signals from atmospheric nuclear blasts.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1965
- Accession Number
- AD0623679
Entities
People
- T. F. Burke
Organizations
- RAND Corporation