| 摘要 |
<p>PROBLEM TO BE SOLVED: To take out digital data and superimposed signal by one set of A/D conversion circuits. SOLUTION: The transmission signal from a transmitter 1, in which an optional weak low frequency signal is superimposed to e.g. digital data subjected to I-NRZI modulation, is transmitted. The noise of wide band is generated 2 and added 3 to the transmission signal, and this signal added with the noise is received by a receiver 4. This received signal is supplied to the A/D conversion circuit 7 through an amplifier 5 and an equalizer circuit 6, then the digitization by the optional over-sampling is performed. This digitized signal is supplied to a digital signal detecting circuit 9 such as e.g. a Viterbi decoder through e.g. PR4 (partial response class 4) equalizer circuit 8, then the transmitted digital data are taken out. Also, the signal from the A/D conversion circuit 7 is supplied to a digital filter 11 for extracting the weak low frequency signal, and this extracted signal is supplied to a signal detecting circuit 12, then the weak low frequency signal is taken out.</p> |
