SU853671A1 - Device for checking reproduction signal phase distortions - Google Patents

Description

(54) DEVICE FOR CONTROL OF PHASE DISTORTIONS OF REPRODUCTION SIGNAL

The invention relates to the field of instrumentation, in particular to a magnetic recording technique, in particular, to devices for controlling digital magnetic recording apparatus. A device for controlling knock is known, comprising a reference frequency generator, a counter, a decoder, an OR circuit, a trigger, a delay line, a two-input circuit AND, and a display unit. This device is simple in design and allows for operative control of instantaneous changes in the duration of the period of a regular (continuous) sequence of output reproduction pulses 1. A disadvantage of the known device is that it cannot control phase distortions (temporal shifts of pulses) of the code sequence of real signal pulses playback. Additional phase distortions appear in the code sequence of reproduction pulses, due to the phenomenon of mutual overlap of pulses of adjacent signal bits. In this case, the vertices of the pulses are shifted by a certain amount towards a larger time interval between the pulses. As the recording density increases, the inter-bit effect of the pulses increases and, accordingly, the error in the measurement of phase distortions by a known device increases. It should also be noted that the known device cannot be used in critical tests, since it gives false readings during the repetition of impulses of reproduction. The closest to the technical essence of the invention is a device for controlling the recording, containing a serially connected reference frequency generator, a key circuit, a counter and a decoder, the first and second outputs of which are connected directly and through the first OR circuit to the first trigger, and the third output is the control input of the key circuit, the delay line connected between the second input of the first OR circuit and the output of the monitored magnetic recording apparatus, also connected to the first input of the two-input AND circuit, second whose input is connected to one of the outputs of the first trigger, the second trigger, St. iiiiiibiM one of the inputs with B | 11khodom second olma or, and the display unit 2 |.

This device can control (l); i; uibK the distortion of one type of real, complex recording-replay signal containing a timing pattern of pulses. In this case, the known device controls the temporary interleaving of the code pulses relative to the clock.

A disadvantage of the known device is that with its help it is not possible to control the phase distortions of a wide class of coded information signals that do not contain clock pulses in their structure.

The aim of the invention is to provide the ability to control the distortion of reproduction signals without clock pulses.

This goal is achieved by the fact that a known device for controlling phase distortions of a reproduction signal containing serially connected reference frequency generator, a key, a counter and a decoder, the first and second outputs of which are connected directly and through the first OR circuit to the first trigger, and the third output - from the control key input, a delay line connected between the second input of the first OR circuit and the output of the monitored magnetic recording apparatus connected also to the first input of the first AND circuit, the second in the stroke of which is connected to the first output of the first trigger, as well as the second trigger, the first input of which is connected to the output of the second OR circuit, and the display unit, introduced the second AND circuit, the output of which is connected to the first inputs of the indicator and the second OR circuit, and also the third trigger and a block for separating the leading edge of pulses whose outputs are connected to the first and second inputs of the second circuit AND, the third input of the latter being connected to the second output of the first trigger, the first input of the third trigger connected to the output of the delay unit, and the third output the decoder is connected with the second inputs of the third trigger and the second circuit OR, the output of the first circuit AND is connected to the second input of the second trigger, the output of which is connected to the second input of the indicator, and the installation input of the counter is connected to the output of the pulse edge selector unit whose input is connected to the output controlled magnetic recording apparatus.

The drawing shows a functional diagram of the ornicbiBaeMoro device.

The device contains a series-connected reference frequency generator 1, a key 2, a counter 3 and a decoder 4, made with three outputs 5, 6 and 7, as well as the first 8 and second 9 of the OR circuit, the first 10,

the second 11 and third 12 triggers, the delay line 13, the two-input circuit And 14, the three-input circuit And 15, the block of the leading edge of the pulses 16 and the display unit 17.

The first 5 and second 6 outputs of the decoder 4 are connected directly and through the OR circuit 8, respectively, to the inputs of the trigger 10. The output of the monitored recording device 18 monitored is connected to the input of the leading edge selection unit 16, the input of the delay line 13 and the first input of the two-input circuit 14 The output of the delay line 13 is connected to the second input of the OR circuit 8 and the first input of the trigger 12. The forward output of the trigger 10 is connected to the bi-miM input of the three-input circuit 15 and the inverse output to the second input of the two-input circuit 14. The second input of the three input circuit 15 is connected to the output of trigger i2, and the third input is connected to the output of the front of the pulse edge 16,

connected, in addition, with the installation input of the counter 3. The output of the three-input circuit AND 15 is connected with the first inputs of the OR circuit 9 and the display unit 17, the second input of which is connected via a trigger 11

5 output two-input circuit And 14,. The third output 7 of the decoder 4 is connected to the second control input of the key circuit. We are 2 and the second inputs of the trigger 12 and the OR 9 circuit, the output of which is connected to the second input of the trigger 11.

0 The device operates as follows.

At the output of the frontal pulse edge selection unit 16, short pulse pulses are formed corresponding to the leading edge of the reproduction pulses coming from the output of the monitored magnetic recording apparatus 18.

The playback pulse triggers the counter 3 and, therefore, the decoder 4 connected to it at 1 inputs through the front edge of the pulses 16, and also enters the delay input line 13 and the first input of the two-input circuit 14.

After that, the decoder 4 forms. Consistently three stable in duration and calibrated time interval.

5 The first reference time interval is between the moment of arrival of the playback pulse (its leading edge) and the moment of the appearance of the first pulse at the first output 5 of the decoupler 4. The second

Q reference time interval lasts from the moment of appearance of a pulse at the first output 5 of the decoder 4 and until the appearance of the second pulse at its second output 6. The third time interval ends at the moment of the appearance of the third pulse

5 at the last, third output 7 of the decoder 4. At the same time, at the forward output of the flip-flop 10 and, therefore, at the first input of the three-input circuit AND 15 during the first interval of time a high 1H is formed, allowing the potential. In the second time interval, a low inhibitory potential is established at the first input of the three-input circuit 15; and then, up to the end of the third interval, a high resolving potential is present again at the direct output of the trigger 10. The third output pulse of the decoder 4, formed at its output 7, is fed to control the input of the key circuit 2 and locks it, and also goes to the second input of the trigger 12 and through the circuit OR 9 to the second input of the trigger 1 1 to set the specified triggers to the initial state the This completes the cycle of operation of the counter 3, the decoder 4 and the trigger 10.

The duration of the generated time intervals is connected in a certain way with the new terminal value of the clock interval of the monitored playback signal. The upper bounds of the first and second calibrated time intervals are determined by U1, the permissible, respectively, lower and upper limits of the deviation of the repetition pulse repetition period.

When the code sequence "1 and" O type ... 000111000 ... arrives at the input of the device, the first playback pulse after the group "zeros in the code signal starts counter 3 and decoder 4 and after some time, determined by the delay line 13, switches the trigger 12. Thus, a high resolution potential at the output of the trigger 12 and, therefore, at the second input of the three-input circuit 15 is only at the end of the action of the pulse at the output of the front-edge selection unit 16.

After that, the device is ready to measure the time interval between the first and second reproduction pulses. The shift (shift) of the location of the second pulse relative to the first characterizes the phase distortion. If the second playback pulse arrives at the input of the device during the operation of the second reference interval, then it will not pass through the three-input circuit 15, but will pass through the two-input circuit 14 to the first input of the trigger 11 and switch it. In this case, the output signal of the trigger 11 will go to the display unit 17 and turn on its second indicator “Norm. At the same time, this second impulse sets the counter to the zero state and thereby restarts it and the decoder 4, and after some time goes to the first input of trigger 12 to confirm its previous state and through the OR 8 circuit to the first input of trigger 10 for setting it to the state corresponding to the first time interval. The device is ready to measure the second interval, which is between the second and third playback pulses. If the next pulse (the third in this

example) will arrive during the operation of the first interval or after the end of the second interval, but before the end of the third interval, the output short pulse of the forefront block of the pulses 16 passes through the three-input circuit AND 15 to the display unit 17 to turn on its first indicator "Failures and OR 9 to the second input of the trigger 11 for switching it to the initial state. The indicator "Normal of the display unit 17 is then turned off. From each output pulse of the three-input circuit 15, which indicates the deviation of the clock periods between the pulses beyond the tolerance limits, the indicator "Failures of the display unit 17 is turned on for a short time each time sufficient for visual observation of the failures. The third playback pulse in the same way sets the counter 3 to the zero state, after which the decoder 4 again sequentially forms three stable time intervals. When a signal after the group of units of one or a group of zeros appears, the third pulse of the decoder, which limits the third time interval, locks key circuit 2 and sets trigger 12 and trigger 11 (if it has been switched) to the initial state. The device is ready to receive the next group of continuously following pulses.

The pulse front selection unit 16 shortens the duration of the reproduction pulses and thereby reduces the impact on the accuracy of the phase distortion estimation of the duration of the pulses, which becomes comparable to the duration of the second allowable time interval.

The technical and economic efficiency of the proposed device consists in expanding the class of problems to be solved by implementing the ability of the device to control the phase distortion of the playback signal of the pulse code sequence.

Phase distortions are manifested as a displacement of the location of the edges of the bit intervals, thereby reducing the difference in detection between adjacent characters. This reduces the noise immunity and increases the likelihood of an error in identifying (in the playback channel) information. With an increase in recording density, the fraction of phase distortions introduced by the inter-bit effect of symbols in the code signal increases.

Claims (1)

Invention Formula A device for monitoring phase distortions of a reproduction signal, comprising a serially connected reference frequency generator, a key, a counter, and a descript