Release Time:2019-03-11  Hits:

Indexed by: Conference Paper

Date of Publication: 2014-07-13

Included Journals: EI

Volume: 3

Page Number: 1848-1854

Abstract: Two approaches, using different noise test signals, can be used to measure the modulation transfer function (MTF) of a linear time-invariant (LTI) system for a narrow band. One is using modulated filtered white noise as input signal and the other using filtered modulated white noise as that into the system. The filtering processes of them are different. This study theoretically analyzed the two approaches and derived relations between the MTF and the transfer function of noiseless system for both cases, based on the ensemble average over the noise carriers. Although the equation introduced by Schroeder can be used to calculate the MTFs from system impulse response, it should be revised when calculating the MTFs for narrow bands. This study also yielded equations for both filtering processes to calculate MTFs in frequency domain for band-pass filters with rectangular function amplitude frequency response. The two equations show the slight difference between the two MTF measurement approaches. Both equations can give explicit and comparable results, which are depended on the system transfer function and the narrow band cut-off frequencies only.