A repeated preamble bit or symbol pattern such as for a binary phase shift keyed (BPSK) communications signal is received within a modem. An initial frequency offset and phase error estimate is generated by processing a Fast Fourier Transform (FFT) that detects the repeated preamble pattern for a block of samples within the communications signal. Two halves of the block of samples are correlated with a plurality of different BPSK shifted sequences to obtain a symbol timing alignment based on the shifted sequence providing the maximum correlation value. A frequency offset estimate is iteratively updated an N number of times using the shifted sequence providing the maximum correlation value to refine an acquisition estimate of the frequency offset and phase error of the received communications signal.