| 摘要 |
PURPOSE:To eliminate a DC component in a recording signal and to improve the activity efficiency of a recording frequency band higher than that in recording modulation at the baseband of a digital signal, by providing a multilevel orthogonal amplitude modulator and a multilevel orthogonal amplitude demodulator. CONSTITUTION:An inputted digital signal, after being time base-compressed at a synchronism addition circuit 21 and a synchronizing signal being attached, is converted to two systems of signal by a parallel conversion circuit 2. They are converted to n-value signals which take values of (n) level in an amplitude direction via multilevel circuits 3 and 5 respectively, and are inputted to a right angle two-phase converter 7 via LPFs 4 and 6. Right angle two-phase conversion is applied by the carrier of a generator 8. The output of the modulator 7 is recorded on a magnetic recording medium 10 via a head 9. The phase reference of the carrier can be obtained, and the reproduction of the carrier is facilitated by providing the multilevel circuits 3 and 5 which output 1 and 0 at a time (t) according to the synchronism addition circuit 21 and the synchronizing signal, and it is possible to heighten the activity efficiency of the recording frequency band by also providing the multilevel orthogonal amplitude demodulator.
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