Abstract: In doubly-spread acoustic underwater channels,the received signal is dispersed in both time and frequency,which makes signal detection particularly challenging.The existing receiver performance is signaificantly degraded.A time-frequency framework is introduced,the proposed time-frequency replica correlator(TFRC) based on short-time Fourier transform(STFT) generalizes existing receivers and considers that both the segmented replica correlator(SRC) and the replica correlation integration(RCI) are the special cases of the TFRC.Computer simulations are carried out to show the efficiency of the TFRC,and a promising substantial improvement in performance is obtained compared with existing receivers over doubly-spread channels.