SU847366A1 - Magnetic tape skew measuring device - Google Patents

Description

Magnetic lect containing digital information leads to false measurement results, since a random impulse sequence is recorded on the magnetic tape tracks.

The purpose of the invention is to make it possible to measure the skew of both control and information tapes.

The goal is achieved in that a device containing two magnetic playback heads, each of which is connected through an amplifier-driver with a corresponding differentiating chain, the first reversible counter, whose inputs are connected respectively via two elements of coincidence to the output of a stable frequency generator, as well as separate trigger and a frequency divider, a sign trigger and an OR element, whose inputs are connected respectively to the outputs of differentiating chains, are entered — the second reversible counter, control The developing input coupled to an output of the frequency divider, the third and fourth elements coincidence zklyuch

valuable between the outputs of the sign trigger and the two counting inputs of the second reversible counter, the fifth, a coincidence element, connected between the inverse output of the trigger and the combined input of the frequency divider and the second input of the second coincidence element, the output of which is connected to the second intakes of the third and invert four elements of the coincidence connected in parallel to the outputs of the first reversible counter, the decoder, the output of which is connected to the second input of the fifth coincidence element, and a comparison unit, as well as a key register, connected nny with comparing unit, the output of which is connected to the reset input of the first down counter and a flip-flop, the direct output of the latter is connected to the second input of the first coincidence element and the input - to the output of OR element.

The introduction of additional elements allows measurement only between those pairs of pulses, the error time between which is less than half the period of the clock frequency.

The drawing shows a functional diagram of a device for measuring tape skew.

The device contains a block of 1 magnetic heads, amplifiers-formers 2 and 3, differentiating circuits 4 and 5, element OR 6, RS sign trigger 7, trigger 8, coincidence elements 9-13, stable frequency generator 14, frequency divider 15, first reversible the counter 16, the second reversible counter 17, the decoder 6, the comparison block 19, the key register 20, the key register 20 dials a code that is numerically equal to half the period of the recorded frequency,

Claims (2)

In the case of measuring the misalignment of the control tape when two magnetic heads are playing from two tracks of the simultaneously recorded signals, they are amplified and limited in amplitude by the shaping amplifiers 2 and 3, they are fed through the differentiating circuits 4 and 5 to the RS trigger inputs 7, s by means of which the determination of the skew sign is performed, and through the OR element 6 to the counting input trigger 8, the forward output of the trigger 8 generates a mismatch signal, which is determined by the magnetic tape skew. The impulse from the direct output of the trigger 8 is applied to one input of the element I3, coinciding thereby allowing the passage of filling pulses from the generator 14 to the summing input of the reversible counter 16. After the filling of the reversing counter 16 begins, the output to the first input appears at the output of the I8 decoder the coincidence element 9. During the pulse action time at the forward output of the trigger 8, the summing input of the reversing counter 16 receives the number of pulses proportional to the skew of the magnetic tape. After the end of the pulse at the forward output of the trigger 8, the coincidence element 9 opens and a signal appears at the output of the frequency divider 15 and the input of the coincidence element 12, through which pulses start to flow to the subtracting input of the reversing counter 16, at the same time they come through the coincidence element 10 or 11 , depending on the sign of the skew and the state of the RS flip-flop 7, to the summing or subtracting input of the reversible counter 17, the number of read pulses is equal to the number of filling pulses, since at a zero value of the reversing count snip 16 allowing descrambler 18 removes the potential from the first input member 9 matcher, and therefore from the element 12 matcher, takes place during read transfer receptacle Cheney misalignment with down counter 1.6 in a reversible counter 17. The time measurement is given by the frequency divider 15. When the information magnetic tape is skewed, a section of the magnetic tape is reproduced, on one of which is more expensive there is no signal, which corresponds to zero values of the digital information. On the key register 20 dial the code corresponding to half the period of the clock frequency of the magnetic tape. When the trigger 8 is started, a reversing counter 16 will begin to fill with a pulse from one of the tracks of the magnetic tape. If the number of pulses arriving at the summing input of the reversing counter, 16, coincides with the code typed on the key register 20, the comparison element 19 will generate a signal which resets the reversible counter 16 and the trigger 8 to zero. This continues from until the signal appears from the second one. magnetic tape tracks, i.e. when the number 16 is not entered into the reversible counter .HQ, less than half the period of the clock frequency. Kaft and when changing the skew of the control tape, this value is read into the reversible counter 17. The measurement takes place until the frequency divider 5, to the input of which signals are given at the time of reproduction, does not affect the stop of the reverse counter 17. Thus, at the end of the cycle Measurements in the reversible counter 17 are the average skew value measured only between those pulses of the magnetic tape, the discrepancy time between which does not exceed half of the clock frequency period. To measure the skew at a different speed of movement of the magnetic tape, it is necessary to change the value of the setpoint on the key register 20. The allowable skew value does not exceed the fourth part of the clock frequency band. Therefore, the value of the set point typed on the key register 20 is advisable with a number of which is not equal to half the clock frequency period. Apparatus of the Invention A device for measuring the skew of a magnetic tape, comprising two magnetic reproduction heads, each of which is connected via an amplifier-shaper with a corresponding differentiating chain, a first reversible counter, the inputs of which are connected respectively via two matching elements to the output of a stable frequency generator, as well as a separate trigger misalignment and frequency divider, which supposes e, with the fact that, in order to provide the possibility of measuring the skew of both control and infor tional tapes device yvedeny sign trigger element and Hilti. the inputs of which are connected respectively to the outputs of differentiating chains, the second reversible counter, the control input of which is connected to the output of the frequency divider, the third and fourth elements of the match, connected between the outputs of the sign trigger and the two counting inputs of the second reversible counter, the fifth element of the match, connected between the inverse output of the error trigger and the combined inputs of the frequency divider and the second input of the second match element, the output of which is connected to the second inputs of the third and even The matched elements are connected in parallel to the outputs of the first reversible counter, the decoder, the output of which is connected to the second input of the fifth matched element, and the comparator as well as the key register connected to the comparator, the output of which is connected to the fault inputs of the first reversible counter and the error trigger. , while the direct output of the latter is connected to the second input of the first element of the match, and the input is connected to the output of the element OR, Sources of information taken into account during the examination 1.Av Orsk certificate USSR № 571828, cl Gil V 27 / 10,20.12.75. 2. USSR author's certificate No. 607273, Cl. G 11 V 27 / 10,30.11.76 (prototype).