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Mobile communications and digital wireless communications are requested high frequency use-rates, more efficient data transmission with limited signal power, frequency band. As multiple users share the same frequency in the mobile communications environment, the spectrum efficiency is getting higher. Moreover, as the effect of the velocity of the mobile object and the terrain surroundings get higher, the digital modulation method is required that the character of linear constant amplitude. In this paper, to restore simply and correctly the received signal of quadrature phase shift keying (QPSK) signal in digital wireless communications, we suggest and simulate an algorithm for detection of QPSK signal using time delay neural networks (TDNN). As the results of simulation, the suggested method is confirmed that the phase information of the QPSK signal is recovered simply and correctly in the mobile …