Remote sensing of moving wide-band sources

Reconstruction of the time dependence and signal parameters of far-field extended wideband sources: Part 1. Reconstruction techniques and technical instruments

“…There is a real possibility of using a linear array located in the near zone of the source parallel to its lat eral axis, instead of a planar array for a variety of pro late sources 2 [6][7][8][9][10]. In the aeroacoustics, a prolate configuration is specific to sources being at one level, i.e., ground and air vehicles and some musical objects (orchestras and choirs).…”

“…It can be solved by using near field horizontal linear arrays [7][8][9]. The problem of reconstruction of the time dependences of far zone signal receive much less attention due to sev eral causes [10].…”

Near-field measurement of radiation levels of extended spatially uncorrelated sound sources

“…Supposedly, with increasing frequency, noise becomes more isotropic in the vertical plane, which is evidenced by the decrease in the difference of the interference immunity of mea surements when using C = I and C = C EX . The SSC 3 Here, represents function (5), integrated in a third octave frequency band.…”

“…The figures presented below show the experimental and theoretical normalized SSC values (20log ) for third octave bands 3 ; the vertical lines denote the boundaries of synthesis region Ω. Normalization tak ing into account the selected Green's function was carried out with respect to maximum signal values measured at large SNRs by single AA receivers. Note that the thus obtained values of normalization factors expressed in dB will also be the RL in the direction of the z axis (θ = -90°) in the corresponding frequency bands.…”

“…As is known, direct measurements of the sound pressure of an emit ter in the far field are often hard to carry out, especially when measuring weak sources in the presence of noise in propagation media having substantial inhomogene ities, etc. To overcome these difficulties, methods have been developed for measuring (reconstructing) the RL in various angular directions using the results of mea suring the near fields of sources by multielement receiver systems [1][2][3][4].…”