Methods to Estimate the Channel Delay Profile and Doppler Spectrum of Shallow Underwater Acoustic Channels

• Published in: Archives of acoustics 2019-01, Vol.44 (2), p.375
• Main Authors: Nguyen, Van Duc, Nguyen, Tien Hoa, Ho, Hoa Xuan Thi
• Format: Article
• Language: English
• Subjects: Bandpass filters; Channels; Fourier transforms; Impulse response; Sounding; Time lag; Transfer functions; Underwater acoustics
• ISSN: 0137-5075; 2300-262X
• DOI: 10.24425/aoa.2019.128501

In this paper, we present the methods to detect the channel delay profile and the Doppler spectrum of shallow underwater acoustic channels (SUAC). In our channel sounding methods, a short impulse in form of a sinusoid function is successively sent out from the transmitter to estimated the channel impulse response (CIR). A bandpass filter is applied to eliminate the interference from out-of-band (OOB). A threshould is utilized to obtain the maximum time delay of the CIR. Multipath components of the SUAC are specified by correlating the received signals with the transmitted sounding pulse with its shifted phases from 0 to 2?. We show the measured channel parameters, which have been carried out in some lakes in Hanoi. The measured results illustrate that the channel is frequency selective for a narrow band transmission. The Doppler spectrum can be obtained by taking the Fourier transform of the time correlation of the measured channel transfer function. We have shown that, the theoretical maximum Doppler frequency fits well to that one obtained from measurement results.