GB1171316A - Improvements in or relating to a method of and apparatus for Recording Signals on a Magnetic Medium - Google Patents

Abstract

1,171,316. Magnetic recording and playback methods. MARCONI CO. Ltd. 30 March, 1967 [12 May, 1966], No. 21208/66. Heading G5R. Signals to be recorded on a magnetic tape 5 are fed through terminals 1 via a pre-amplifier circuit 2 to a pulse width modulation circuit 3 as modulation input. The output of this circuit is fed to a magnetic record head 4 through resistors R1, R2. Magnetic tape 5 moves relative to the head 4. The pulse repetition frequency of circuit 3 is high relatively to the highest frequency in the signal to be recorded and in operation this high frequency constant effects the magnetic biasing of tape 5. Tape 5 records the mean value of the pulse width modulated signal. Signal reproducing apparatus, Fig. 1b, may be combined in a single unit with the recording apparatus of Fig. 1a, the pulse width modulation circuit and the preamplifier circuit being used both for recording and reproducing. When used for the reproduction of signals from tape 5, the output of the pulse width modulation circuit is fed to a detector circuit which may be an integration circuit or a low-pass filter arranged to have a sufficiently high upper limit frequency to pass the highest frequency of the recorded signal but to reject the pulse repetition frequency content of the pulse width modulation circuit output.