Accession Number : ADA116458

Title :   Effects of Filter Response on Analysis of Aircraft Noise Data.

Descriptive Note : Final rept.,

Corporate Author : WYLE LABS EL SEGUNDO CA

Personal Author(s) : Sutherland,Louis C

PDF Url : ADA116458

Report Date : May 1982

Pagination or Media Count : 83

Abstract : This report analyzes the effects of non-ideal filter transmission characteristics upon the measurement, correction, or extrapolation of aircraft noise dat a. The report is based primarily upon, and represents an abbreviated summary of, two previously published, more detailed reports on this topic. The basic approach used to correct aircraft spectra for analysis errors due to finite filter sidebands and signal spectrum slopes involves defining same type of approximation to the true spectrum shape of all frequencies. The closer this approximation is to the true spectrum slope, the more accurate the correction for filter effects. This report reviews several such filter effect correction methods of varying degrees of accuracy. Measurements on the ground of noise from aircraft in flight can involve propagation distances of the order of 300 to 2,000 m or more. In this case, band levels at high frequencies can be substantially in error, by more than 10 dB, unless filter effects are considered. However, it is also shown that while the band levels may be subject to large errors due to filter effects , errors in composite noise levels such as PNL, LA or EPNL will usually be small - less than 1 dB.

Descriptors :   *Aircraft noise, *Electric filters, Acoustic measurement, Spectrum analysis, Accuracy, Errors, Corrections, Spectra, Frequency bands, Sidebands, Spurious effects, Frequency response, Signal processing

Subject Categories : Active & Passive Radar Detection & Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE