SU1550577A1 - Device for estimating reliability of information transmitting channels - Google Patents

Abstract

The invention relates to instrument engineering and can be used to assess the reliability of information transmission channels of magnetic recording apparatus. The device comprises a generator 5 associated with the recording head 2 and the first analog-code converter 6, the output of which is associated with the meter 8 of the mutual correlation function, to the second input of which is connected through the second converter 9 analog-code playback head 3. With other The inputs of the converters 6 and 9 are connected to the master unit 10, and the output of the meter 8 is connected via the control unit 11 and the first division unit 12 to the input of the second division unit 13, the output of which is connected to the input of the display unit 14. In addition, the device is equipped with switches 17, 18, a conditional probability meter 19, and a summation unit 20, which make it possible to improve the accuracy of estimating channel reliability. 2 Il.

Description

phases

The invention relates to instrument engineering and can be used to assess the reliability of information transmission channels of magnetic recording apparatus.

The purpose of the invention is to improve the accuracy of channel reliability estimates.

FIG. 1 shows a functional diagram of an apparatus for evaluating the reliability of information transmission channels; in fig. 2 tapes recorded (a) and reproducible (b) from a magnetic tape signals.

The device contains the investigated magnetic recording apparatus 1 with magnetic recording heads 2 and reproducing 3 and magnetic tape 4, the gene Irator 5 whose output is connected | To the input of the recording head 2 and to the first input of the first converter 6 is ana- | log code, the output of which is connected to the first inputs of the delay unit 7 and the first meter 8 mutually correlated V0 - the average speed of the magnetic tape movement. The magnitude of the unreliability of information transmission channels in magnetic recording apparatus is characterized simultaneously by an amplitude and frequency distortion function, the second input is connected to the second input by a second analog-code output of the reproducing head 3 via the second converter 9. The first output of the master unit 10 is connected to the second inputs of converters 6 and Y are analog-code, and the output of meter 8 of a mutually correlation function is connected via control unit 11 and first dividing unit 12 from perteln signal recorded on the magnetic tape which moves with an average velocity relative to the working Vtf- aazorov magnetic heads. If the reproduced signals are not distorted with respect to the recorded signals, i.e. There are no interferences in the information transmission channel directly distorting the recorded and

15505774

N is determined based on the expression a percent.

4H

Ј .CYj / X,)

Ј, v0

 100, %,

where P (Y / X ,.) are conditional probabilities

reproducible signals Y | regarding signals recorded on a magnetic tape

XP

m is the number of quantization levels of the recorded and reproduced signals;

V0 is the average speed of the magnetic tape. The magnitude of the unreliability of information transmission channels in magnetic recording apparatus is characterized simultaneously by the amplitude and frequency distortion of the reproduced signal relative to the signal recorded on a magnetic tape, which moves at an average speed Vtf- relative to the working aazors of the magnetic heads. If the reproduced signals are not distorted with respect to the recorded signals, i.e. There are no interferences in the information transmission channel directly distorting the recorded and

the input of the second block 13 division, 35 reproducible signals in amplitude

the output of which is connected to the input of the first display unit H. The output of the analog-code converter 9 is connected via the second meter 5 of the mutually correlation function and the comparison unit 16 with the first switches 17 and 18. The outputs of the latter are connected via the conditional probability meter 19 and the summation unit 20 to the second input of the second division 13. The second 45 data transmission by interference, the direct output of the control unit 11 through the delay unit 7 is connected to the input of the second meter 15 of the cross-correlation function and the input of the switch 17. The switch 18 input is connected to the output of the analog-code converter 9, The outputs of the master unit are connected respectively to the input of the first block 12 divisions and through the comparison unit with the input of the second display unit 21.

The device works as follows.

Evaluation of the unreliability of transmission channels in magnetic recording apparatus

and in phase, then all Р (Ґ- / Х) 1 at jФ i are equal to 0 and at equal to 1. Thus,

(n tn

SL ZPttj /X.(Y.

.

When the channel is completely clogged, it distorts the recorded and reproduced signals in amplitude and phase,

m t GR (U. / X,) {o, P (U; / X.)

  ;

LN

lay t

K, veTak dependence of the magnitude of the unreliability of the information transmission channel in magnetic recording devices corresponds to the physical meaning of the expression

rate of movement of a magnetic tape

In assessing the unreliability of information transmission channels in magnetic recording apparatus, the distance S between the working gaps of the recording and reproducing head, which is fixed in the driver unit 10, is first determined, and the ratio of the useful signal / noise, which is caused by is selected by the quantization level of the recorded and reproduced signals m, which is set in the receiving unit 10, from the first output of which this value is supplied as a voltage to the inputs of the converters 6 and 9 analogue code.

Next, the recorded working information 2d ci from the generator 5 through the recording head 2 enters the magnetic tape k in the magnetic recording device 1 and the analog-code to the first input of the converter 6, and after a certain time from the 25 output of the reproducing head 3, the signal arrives at the first input of the converter 9 analogue code. Depending on the technical level of the magnetic recording apparatus, the reproduced signals will be distorted relative to those recorded in amplitude and phase. Next, the signals quantized at a level equal to the number m, and in time in converters 6 and 9, the analog-code is fed to the second and first inputs of the first meter 8 of the mutually correlation function. The meter 8 determines the delay time C of the reproduced signal with respect to the recorded one (FIG. 2). Time C is directly dependent on the average speed of movement of the magnetic tape and on the distance S.

A signal proportional to time 45 Ј is fed to the input of control unit 11, from the output of which simultaneously the corresponding voltage is proportional to

the output signal to etopou and the first input of the second gauge 15 of the cross-correlation function and the accuracy of determining the delay time is estimated. The value obtained from the second gauge 15 of the mutually correlation function is fed to the first input of the comparison unit 16, to the second input of which the signal from the third output of the delay unit 10 is proportional to the required accuracy value of the delay time estimate -Ј. If the required accuracy of the delay of the recorded signal does not correspond to that reproduced from the comparison unit 16, a signal is sent to the second display unit 21. This block signals that the device for estimating the unreliability of signal transmission channels has a faulty system for estimating the delay time C or that the magnetic recording apparatus is experiencing a strong drift in the average speed of the magnetic tape, or the movement of the magnetic tape has stopped, for example, if it breaks. In the case when the obtained accuracy of the delay time corresponds to the specified one, from the comparison unit 16 a signal arrives at the first inputs of the first 17 and second 18 switches and opens them. The second inputs of these switches receive the recorded signal delayed by time из from the delay unit 7 and the reproduced signal from the output of the converter 9 analog-code. From the outputs of the first 17 and second 18 switches, signals simultaneously arrive at the first and second inputs of the evaluation unit 19 of the conditional probabilities of the reproduced signals with respect to the recorded ones. In this block, matrices of conditional probabilities of the reproduced signals are formed relative to the recorded, quantized in amplitude and in time. The conditional probabilities P (Y./X;) are calculated as follows. In the recording

At the first input of the first signal block 50, the number of samples is counted.

not

division, in which the ratio C toЈ.jV0 is determined. The voltage value t also enters the second input of the delay unit 7, in which the delay time is set to C. From the outputs of the delay unit 7 and the converter 9, the analog code arrives simultaneously at the same time55

(N3an) whose amplitude lies within a fixed level, i.e. from X to LX + X. Then, in the reports corresponding to the samples of the played signal, the amplitudes of the reproduced signal are checked Nflocn Y) - Thus, the density of the conditional probabilities

recorded over time and reproduced by

g

d 5 0

five

five

the output signal to etopou and the first input of the second gauge 15 of the cross-correlation function and the accuracy of determining the delay time is estimated. The value obtained from the second gauge 15 of the mutual correlation function is fed to the first input of the comparison unit 16, to the second input of which the signal from the third output of the delay unit 10 is proportional to the required accuracy value of the delay time estimate -Ј. If the required accuracy of the delay of the recorded signal does not correspond to that reproduced from the comparison unit 16, a signal is sent to the second display unit 21. This block signals that the device for estimating the unreliability of signal transmission channels has a faulty system for estimating the delay time C or that the magnetic recording apparatus is experiencing a strong drift in the average speed of the magnetic tape, or the movement of the magnetic tape has stopped, for example, if it breaks. In the case when the obtained accuracy of the delay time corresponds to the specified one, from the comparison unit 16 a signal arrives at the first inputs of the first 17 and second 18 switches and opens them. The second inputs of these switches receive the recorded signal delayed by time из from the delay unit 7 and the reproduced signal from the output of the converter 9 analog-code. From the outputs of the first 17 and second 18 switches, signals simultaneously arrive at the first and second inputs of the evaluation unit 19 of the conditional probabilities of the reproduced signals with respect to the recorded ones. In this block, matrices of conditional probabilities of the reproduced signals are formed relative to the recorded, quantized in amplitude and in time. The conditional probabilities P (Y./X;) are calculated as follows. In the recording

the signal counts the number of samples

(N3an) whose amplitude lies within a fixed level, i.e. from X to LX + X. Then, in the reports corresponding to the samples of the played signal, the amplitudes of the reproduced signal are checked Nflocn Y) - Thus, the density of the conditional probabilities

Nsocn y P (Y./Xj) DH “- -.

Jh3cm

Next, the resulting conditional probability flags are logarithmized and summed up in summation unit 20, from the output of which the signal Ea arrives at the first input of the first unit 13, and, at its second input, a signal proportional to the Mina value is received. Thus, from the first dividing unit 13, a signal arrives at the first AND block, which indicates the unreliability of the channel. numerical discrepancy in amplitude and phase of the reproduced signal - pa relative to a fixed recorded signal.

If the information recorded in the form of pulse signals is used in the magnetic recording apparatus, then in the device, instead of the 6 AND 9 converters, the analog-code, you must use code-code converters.

Claims (1)

Invention Formula A device for assessing the reliability of information transmission channels, containing a magnetic recording apparatus with recording and reproducing heads, a magnetic tape, a generator, an up-set block) a master unit, which differs from that evaluation, it is equipped with two analog-code converters, two meters of the mutual correlation function, two division blocks, a delay block, a comparison block, two display blocks, a conditional probability estimator, Q 0 five 0 five two switches and a summation unit, the generator output is connected to the recording head and through the first analog-code converter to the first inputs of the delay unit and the first meter of the mutual correlation function, the output of which through the control unit is connected to the first input of the first division unit, whose output is connected to the first input of the second dividing unit, the output of the reproduction head through the second converter analog-code is connected to the second input of the first meter of the mutual correlation function and the first input of the second Mutual correlation function meter, the output of which is connected through the comparison unit to the first inputs of the first and second switches, the outputs of which are connected respectively to the first and second inputs of the conditional probability meter, whose output is connected to the first display unit through the series-connected summation unit and the division unit , the first, second and third outputs of the master unit, respectively, are connected to the second inputs of the first and second converters analog-code, with the second input of the first division unit and with the second input of the comparator unit, the output of which is connected to the input of the second display unit, the second output of the control unit is connected to the second input of the delay unit, the output of which is connected to the second input of the second meter of the cross-correlation function and the second input the switch is connected to I with the output of the second converter analog-code. FI.2