SU853649A1 - Method of recording and reproducing electric signals - Google Patents

Description

(54) METHOD OF RECORDING AND REPRODUCTION OF ELECTRICAL SIGNALS

The invention relates to the field of instrumentation and can be applied in various devices, including magnetic recording devices using angular modulation types, including frequency modulation. Various methods of analogue accurate magnetic recording and reproducing electrical signals are known using angular modulation types: frequency modulation, frequency pulse, pulse width, phase and time-modulation modulation 1 In the known methods, the analog signal is converted to modulation used, recording the converted signal on one track of the carrier or on two tracks, playing back the recorded signals, “reverse converting them to the original signal and I n n al. In the known methods, the ability to register analog signals is determined by the bandwidth of the recording path: signals of a complex spectrum with individual components that exceed the upper frequency band of the path band in frequency cannot be recorded without significant distortion. The closest in technical essence is a method of recording and reproducing electrical signals from a magnetic tape, the frequency of which exceeds the upper frequency of the recording bandwidth, in which the high-frequency analog signal is converted into a high-frequency signal with angular modulation, decomposition of the converted high-frequency signal rectangular shape into slightly lower frequency signals shifted in phase by the interval between the edges of the original converted high the frequency signal, each lower frequency signal is recorded on separate tracks of the magnetic tape (recording-playback channels), while ensuring that the low-frequency converted signal spectrum is matched to the recording-playback channel bandwidth, and when playing from low-frequency converted signals, restoration of the converted high-frequency signal and its false transformation into the original analog signal 2,

This method registers high-frequency signals in devices with lower frequency bandwidth.

However, this method does not allow accurate and noise-resistant recording of information signals due to the significant influence of a number of destabilizing factors.

The aim of the invention is to improve the noise immunity and reliability of reproduction of the analog information signal.

In order to achieve this goal, in the method of recording and reproducing electric signals with angular modulation, in which the angular modulation of the information analog signal is carried out, the n signal is formed from the received signal (where n is an integer greater than 1) the signal is n times, and shifted in time relative to each other by half their period, recording the signals shifted in time on separate information tracks of the carrier, the subsequent reproduction and amplification of these shifted signals , the formation of each of them of pulse sequences, as well as the summation of these sequences and the conversion of the total pulse sequence into an analog signal, simultaneously with recording the signals shifted during the time, record two identical signals of stable frequency on one auxiliary tracks, and during playback these stable signals are converted into correction signals for the reproduced signals of the information carrier tracks, after which they are carried out using These correction signals are antiphase regulation of the formed pulse sequences from the information tracks of the carrier.

The time diagram of the drawing shows the sequence of operations with signals for a given crio, for example, in relation to frequency modulation and for n 2.

Analog signal 1c upper cha. Hz spectrum is converted into a frequency-modulated signal 2; at the same time, they provide the necessary carrier frequency ratio d to the frequency Fg, adopted in the frequency-modulated recording technique and allowing for a high-quality inverse conversion of the signal to analog when played back. From the frequency-modulated signal 2, two signals 3 and 4 are formed with a frequency two times lower than the frequency of signal 2, tied to the edges of signal 2 and shifted in time with each other by a Friend by an amount equal to half the signal's period 2. Signals 3 and 4 record each on its own carrier track. In this case, the spectrum of signals 3 and 4, two times narrower than the spectrum of signal 2, must be matched with the capacity of the recording-reproduction channel (carrier-head system). Signals 5 and 6 of a stable frequency, for example, of a rectangular shape, are recorded simultaneously on two tracks of the carrier, for example, on the outermost tracks. One of the tracks is considered to be the reference one (for example, with signal 5). The duration of these signals is determined by the possible maximum relative temporal fluctuations between the signals from these tracks during playback, caused by misalignment of the carrier, displacement of head gaps, etc. factors.

The recorded signals 5 and b, when played from the respective tracks of the carrier, are amplified, limited. These signals 7 and 8 due to tape misalignments, displacement of head gaps and other factors are additionally shifted in phase (in time, & t) different from each other compared to signals 5 and 6. Signal 8 with additional signal ahead 7 is indicated in the drawing dashed line, and when lagging it - continuous.

An additional phase shift between signals 7 and 8 using conventional pulse-width demodulation (with reference, for example, to the leading edges of the signal 7 and the falling edges of the signal 8) is converted into the signal 9 of the time error correction ( a b - maximum signal advance 8 relative to signal 7).

The advantage of this demodulation in this case is that the correction signal 9 is not very sensitive to longitudinal velocity variations, to a stable average velocity, i.e. depends mainly only on distortions and other factors that determine the relative temporal displacements between signals on different tracks.

From signal 9, the operation of normalizing the correction signal is performed with the necessary division factor for each information track, where signals 3 and 4 were recorded. the coefficient for the track adjacent to the track of the signal 7 (5) is 1/3, and

with a track of a signal 8 (6) - 2/3 (division operations).

When recording signals 5 and 6 on adjacent tracks, it is necessary to perform operations of multiplying signal 9 by K times where K is the number of tracks between the reference and information tracks. The relative time errors in each of the pulsed sequences 3 and 4 generated during reproduction of the recorded signals 10 and 11 corresponding to the time-shifted fronts of the signals 3 and 4 are corrected. corresponding normalized correction signals before obtaining pulse sequences 12 and 13 with the law on the temporal position of the fronts, the corresponding law relative position - the fronts of signals 3 and 4. This provides recovery phase relations in the reproduced signals and eliminate the effect of destabilizing factors.

The pulse sequences 12 and 13 after the summation operation (signal 14) with the time law of the fronts position, corresponding to the law of the fronts position of the signal 2, are dedured to the analog signal 15 corresponding to the original analog signal 1 during direct modulation,

Claims (1)

1.Aksenov V.D., Visches A.I. and Gi.tlits MVTochna magnetic record, M, Energie, 1973, s, 6. 2, For France 2339926, cl. G 11 B 5/02, published. 1977 (prototype) iF