| 摘要 |
<p>An apparatus for deriving amplitude values from an input information signal is proposed, which amplitude values can be used as reference levels for the states of a finite state machine, which are needed for the computation of the likelihood functional in a partial response maximum likelihood bit detection apparatus. The apparatus comprises: input means (1) for receiving the input information signal, conversion means (2', 6) for deriving a digital signal from said input information signal, said digital signal comprising an array of bits of a first or a second binary value occurring at bit instants with a specified bit frequency, detection means (8) for repeatedly detecting a state from subsequent sequences of n subsequent bits in said digital signal, said subsequent sequences being obtained by shifting a window of n subsequent bits each time over one bit in time, sample value determining means (2) for deriving sample values from said input information signal, one sample value for each of said sequences of n bits, said one sample value for a sequence of n bits corresponding to the signal value of said input information signal at a predetermined time instant lying within said window corresponding to said sequence of n bits, processing means (4, 12) for processing the sample values belonging to sequences of n bits of the same state, and for carrying out this processing step for all possible states, so as to obtain a processed signal value for each possible state, output means (20) for supplying the processed signal values for each possible state as the amplitude values that can be used in the partial response maximum likelihood bit detection apparatus.</p> |
