This invention relates to a magnetic recording and reproducing system in which a frequency-modulated signal is recorded and reproduced, and is directed more particularly to such system in which a further signal is recorded and reproduced so that any wow and/or flutter components are separately extracted from the recovered further signal to implement noise cancellation during reproduction of the recorded signal.
For a magnetic recording and reproduction of audio signals or the like using a magnetic tape an AC bias recording system is commonly employed. In such a system a high-frequency bias signal of 50 KHz to 200 KHz is superimposed on an audio signal during recordation to linearize the magnetization curve of the tape. This system provides excellent recording sensitivity and a low distortion factor as compared with biasless and DC bias recording systems. An AC bias recording system, however, is not satisfactory with respect to its distortion characteristics and suffers from the further disadvantage that is difficulty in handling DC signals as required in a general purpose recording system. Therefor an FM recording system has been proposed to overcome the above disadvantages in the AC bias recording system. However, in the FM recording and reproducing system, wow and flutter in a recording medium transport mechanism causes a noise in the recorded and/or reproduced signal. This problem of frequency-modulation noise due to wow and flutter is common to virtually all FM recording and reproducing systems. The generation of wow and flutter depends on a number of complex factors, however, such as the cleanliness and contact condition of the tape and head surfaces, the tape flexibility, temperature, moisture, and the tape transport system. Therefore no satisfactory solution has been proposed to this problem. A DC signal can be recorded and reproduced using frequency modulation, but this does not avoid the plaguing problem of FM noise due to wow and flutter.