High performance digital communications in mobile channels

Random amplitude and phase modulations experienced in mobile channels result in a number of system limitations and link impairments. In this paper, a novel approach named "tone calibrated technique" which mitigates multipath fading induced distortions in a digital link is presented. It is shown that a low power pilot tone can be used to continuously calibrate a mobile link against time varying impairments. Coherent demodulation of data is possible by means of the pilot tone without using a conventional tracking loop. Since very little power is consumed by the pilot tone, the performance of the tone calibrated technique is only marginally below BPSK in an unfaded environment.