| 摘要 |
PURPOSE:To make a device operate favorably under low S/N, and to make a phase following characteristic good by estimating a transmission signal by comparing the states from the past to the present of the amplitude and the phase of a reception signal and the states from the past to the present of the amplitude and the phase of a reference signal. CONSTITUTION:A comparing means 63 is constituted of a delay and conjugate operating part 59 consisting of a delay circuit 67 and a conjugate operating part 69, a reference signal generating part 71, a subtracter 73 and the square operating part 75 of an absolute value. A maximum likelihood estimating means 65 is provided with a viterbi algorithm operating part 77. The subtracter 73 obtains difference between the reference signal outputted from the reference signal generating part 71 and the output signal of a multiplier 61. The square operating part 75 of the absolute value calculates the square of the absolute value of the output signal of the subtracter 73 as a branch metric. The viterbi algorithm operating part 77 executes the maximum likelihood estimation for the branch metric i.e., the output signal of the square operating part 75 by viterbi algorithm, and outputs decoded data. |
