| 摘要 |
PURPOSE:To adopt the heterodyne audio frequency system to simplify a low frequency circuit for recording and improve amplitude and phase characteristics by performing the frequency modulating/demodulating operation with a frequency higher than the frequency of a frequency modulated audio signal recorded on a magnetic tape. CONSTITUTION:Right and left audio signals processed by an audio input circuit 3s are applied to frequency modulating circuits 41 and 42 and have frequencies modulated by a prescribed frequency and are added by an adder 5 and have frequencies converted in frequency converters 6a and 6b by pilot signals. These frequency modulated signals are processed in LPF circuits 8a and 8b, adders 11a and 11b, etc. in succeeding stages and are recorded on a magnetic tape 2. Reproduced audio signals are inputted to BPF circuits 15a and 15b and changeover switches 17a and 17b of a reproducing circuit, and the pilot signals from oscillators 7a and 7b are applied to frequency converters 16a and 16b similarly to converters 6a and 6b of a reproducing system. Thus, the heterodyne audio frequency modulating/demodulating operation is performed, and the audio frequency system is adopted to simplify the low frequency circuit for recording and improve amplitude and phase characteristics. |
