Analysis of possible interference in radio altimeters induced by a position marker system called RASP

An analysis is given of possible interference induced by a position marker system, called RASP, into aircraft radio altimeters. The RASP system is used as a marker beacon in flight tests for trajectory measurements, and operates on 4.3 GHz. It is concluded that radio altimeters will not experience any harmful interference from a RASP transmitter.

Calculation of sound suppression in a circular three - sectioned uniform flow duct

It is concluded from this limited analytic study of pure tone sound suppression in a cylindrical duct with uniform flow, based on the mode matching technique, that the optimum of the liner impedance heavily depends on the source distribution and also on the length of the duct.

Calculation procedure for soimd propagation in a multisectional duct with uniform flow

A set of equations is presented for the sound propagation in an axisymmetric multisectional duct. For each side of a source section the combined duct effects of transmission, reflection and absorption are reduced to one matrix of coefficients. The procedure is compatible with a source description which takes the feedback of the sound field into...

Sound transmission in and radiation from hard-walled annular ducts related to fan engine inlets

In this report the sound propagation in a hard-walled annular duct of finite length is investigated. The individual modal solutions so found are described. The main properties which are calculated in the present report, are the modal intensity and the modal far field directivity pattern. The modal intensity is determined by the rate of mode...