Systems and methods include a method for determining wave propagation speed. Spatio-temporally-sampled data for electromagnetic (EM) wave propagation through a fluid in a conduit is acquired for different instants of time from each antenna of an array of antennas distributed at predetermined locations. A k-ω plot plotting curves having a kinematic relationship ω=ck is generated based on the spatio-temporally-sampled data and using a spectral-based algorithm, where ω is an angular frequency of a spectral component of EM disturbances, k is a wavenumber, and c is an unknown speed of the EM wave propagation. A spectral ridge on the curves is identified using the k-ω plot. Parameters for calculating a slope of the spectral ridge are determined. The slope of the spectral ridge is determined. The speed of EM wave propagation is determined assuming a relation between the speed of EM wave propagation and the slope of the spectral ridge.