SU720488A1 - Device for synchronizing data displayed from rotary magnetic carrier - Google Patents

Description

I

The invention relates to instrumentation, in particular to magnetic sanHcvi apparatus on a portable media.

A device for magnetic recording and reproducing information, containing a discrepancy scheme, an OR scheme, several triggers, and a delay line C1, is known.

This device allows to obtain increased accuracy of reproduction, however, the device is not applicable. For synchronization of the reproducible magnetic information carrier.

To synchronize the recording onto the rotating magnetic (the information carrier is usually used a special servo track, pre-printed on the media, which allows recording information with the same density throughout the entire rotation of the carrier. Since the servo track is reproduced under conditions of strong electromagnetic pickups caused by the flow of recording currents, as well as from - due to the finite bandwidth of the playback path, the obtained reference clock signals can iBvferb significant phase distortion, then there is a path noise immunity insufficient for reliable synchronization.

The closest in technical terms to the present invention is an arrangement for synchronization of reproducible information from a rotating magnetic information carrier. Containing a feedback-covered, serially connected phase detector, a filter and a controlled oscillator connected between the input and output terminals of the clock signals and the input terminal of the start of carrier signal (2.2 ;.

However, the use of this device reduces the accuracy of synchronization in the initial part of the servod track, which is associated with the transition processes in the phase auto-tuning system during the initial establishment of synchronization. Transitional processes occur in the system due to the impulse at the end and at the beginning of the servo track (the meukutsu post / henny pulse of the servo track, preceding the start signal of the carrier, and the first impulse of the servo track, following the start turn signal, is not a multiple of the interval between the pulses in the middle of the servo track) and continue until the common mode is established. B, the transient phase of the sync signal at the output of the sync generator does not follow the phase of the servo pulses, and even their frequencies may differ significantly.

The purpose of the invention is to improve the synchronization accuracy.

This is achieved by introducing in series the coincident circuit and driver connected between the BxonjibiM sync terminal and the input of the phase detector, as well as the serially connected delay lines and the trigger connected between the second input of the oscillator and the sync terminal. The second trigger input is associated with a clamp of the p6opota start signal of the carrier and is loaded onto the second input of the Matching circuit.

Fig. "1 depicts a structural scheme of a preset device for synchronization, | on, 2 - time diagrams of his work

The device comprises ring-connected (one-time detector 1, filter 2, controlled generator 3, input driver 4, coincidence circuit 5, trigger 6 and delay line 7.

The controllable generator 3 is forced on the output bus 8 rectangular banks, the frequency of which can vary under the influence of the control voltage fia at the first input. The appearance of a zero signal at the second input of the controlled oscillator 3 leads to a breakdown of the oscillations, which are renewed one time with the removal of the inhibit signal. The controlled oscillator 3 can be constructed, for example, according to a symmetrical multivibrator circuit. Input formate; pe 4 can be made in the form of a vibrator, and the trigger 6 - in the form D of the trater. The first input bus 9 receives the generated servo track pulses, the second input bus 1O receives a signal for the beginning of the carrier rotation. This signal is depicted in FIG. 2a, and on flash, 2b servo track pulses are shown

Claims (2)

For each servo impulse that passes through the coincidence circuit 5, the driver 4 generates a reference signal (Fig. 2c) of a fixed duration. The coincidence circuit is opened by permitting voltages from the output of trigger b (Fig. 2d). Since at the second input of the controlled oscillator 3 there is also an allowable voltage level (Fig. 2e), the controlled oscillator continuously produces rectangular pulses from Figs. 2e, which are compared in phase with the reference signals of the phase detector 1, the phase detector generates phase error signals, the shape of which is shown in FIG. In the established synchronization mode, the place before the arrival signal of the beginning of the rotation, the outgoing signal of the controlled oscillator 3 and the reference signal of the former 4 maintains a certain time shift, close to a quarter of the servo track pulse period. If throughout the whole carrier revolution the pulses of serbo-horns follow with a constant period T (between pulses 11 and 12 on the diagram fkg. 2), then the pause between the last impulse 12 of the servo track and the first impulse 13 of the next turn, the carrier's tp may be arbitrary. trigger 6 (Fig. 2d), which turns off the controlled oscillator 3. The first impulse 13 of the newly reproduced servo track energizes, trigger 6, and after 1 time interval of the delay line 7 the output signals of the device begin to form again. To ensure common mode, the device requires that the delay time is equal to the steady-state time. The duration of the start turn signal is sufficient for advancing the controlled oscillator 3, i.e. to set its time for the reference circuit to its original state. If the time required for this is several servo-periods, the coincidence circuit 5 prevents the occurrence of spurious signals of phase error in the phase-locked loop. Since an inertial filter is included in the auto-tuning ring, the frequency of the controlled oscillator does not have time for how many changes during the pause time. Thus, the output signals of the device, starting from the first, are followed by the synXJX5HHO and cHH4ia3Ho servo pulses {yugki npnsfeiieHiie of this device, which will significantly improve the accuracy of synaph 72 chropization on the initial portion of the servo track and improve the quality of the information recorded in the storage drive. Apparatus of the Invention A device for synchronization of a reproducible magnetic information carrier containing feedback-connected serially connected phase detector, a filter and a controlled oscillator connected between the input and output terminals of the sync signals, and the input terminal of the signal for the beginning of the carrier rotation, characterized by that, in order to increase the accuracy of synchronization, sequentially connected coincidence circuits and a driver connected between the input terminal of the sync signal and the input of the phase detector, as well as successively connected delay lines and a trigger, connected between the second input of the controlled generator and the input terminal of the clock signals, while the second trigger input is associated with the terminal of the start turn signal of the carrier, and its output is loaded at the second input of the coincidence circuit . Sources of information taken into account in the examination 1. USSR author's certificate number 503280, cl. G 11 B 5 / GS, 1974. 2. Chulkov V. A. and others. Device for automatic synchronization of drives on magnetic drums and discs. Sat Questions radio electronics, ser. EVT, 1974, no. 12, p. 1O7 (prototype). 1gHgTsr-1G - iG