1. Field of the Invention
The present invention relates to an apparatus for recording and/or reproducing digital information signal which is suitable for use in, for example, recording an audio PCM signal on a magnetic tape by a rotary head.
2. Description of the Prior Art
In the case where a plurality of sampling frequencies, for example, 44.1 KHz and 48 KHz, are selectively used for modulating an analog audio signal into an audio PCM signal, it is desirable that the audio PCM signals of any sampling frequencies can be recorded and reproduced in the same apparatus.
In a conventional PCM tape recorder with a rotary head, in order to keep a recording density constant, the running speed of a magnetic tape and the operation speed of a recording processing circuit are varied in proportion to the sampling frequency of the audio PCM signal to be recorded.
There is, however, a problem that many parts must be switched or altered according to the sampling frequency.
First of all, it is necessary to switch a reproducing equalizer circuit and a PLL (Phase Locked Loop) circuit for clock reproduction and, it is also necessary to switch a capstan servo circuit and a drum servo circuit to change the running speed of a magnetic tape. Furthermore, another inconvenience occurs in that recording time per one cassette is changed, when the tape speed is varied. Moreover, there is such a defect that it is difficult to coincide the time code for editing with absolute time at the different sampling frequencies.