SU547831A1 - Method for measuring non-linear distortions in magnetic recording equipment - Google Patents

Description

The invention relates to a magnetic recording technique, in particular, to methods for measuring non-linear distortions in magnetic recording equipment.

Methods are known for measuring non-linear distortions in which, when measured, the level of the test signal 1 | &

Of the known methods, the closest in technical essence and effect achieved to the described one is a method of measuring nonlinear distortions in magnetic recording equipment by recording and reproducing reference and test signals, the last of which is recorded at higher or lower levels, when the test signal is played back signals of higher and lower levels, reducing the separated signals to a constant value and then measuring nonlinear distortions by the difference between the reduced signals in s J.

When measured in a known manner, non-identical recording channels of the test signal reduces the measurement accuracy.

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

To do this, according to the proposed method, when recording, a test signal is formed from a reference signal in the form of a pseudo-random binary sequence, and the larger and smaller levels are interleaved and, moreover, during reproduction, before the separation of levels, the reference signal is delayed, the pseudo-binary binary sequence is generated from the delayed signal, then this sequence mutually KOf is aligned with the reproduced test signal, and after separation the signal of a higher level is delayed.

The drawing shows a block diagram of a device that implements the proposed method.

In the recording mode, the reference signal from the generator 1 is fed to one of the channels 2 of the magnetic recording apparatus 3 and the generator 4, at the output of which a test signal in the form of a pseudo-random binary sequence is generated from the reference signal of the generator 1. The test signal of a higher level is removed from the output of the generator 4, and a smaller level from the attenuator 5. The interpreter 6 periodically connects these signals to the input of the test channel 7 of the magnetic recording equipment 3. In the playback mode, the reference signal from the output of channel 2 after being formed in block 8, and the delay in block 9, goes to generator 10, at the output of which a pseudo-random binary sequence is formed from the reproduced reference signal. The signals from the output of Scal 7 and generator 10 are mutually correlated by the correlator 11, from whose output through switch 12 a signal of a higher level enters the block 13 of a delay, and a signal of a lower level goes to a snubber 14, the gain factor of which is attenuated by the attenuator 5. As a result of the above transformations at the output of the correlator 11, the signal will be proportional to the pulse transient function of the test channel 7. With a small level of the test signal, the pulse transition function does not depends on the nonlinearity of the amplitude response and

of the test channel, with a higher level of the test signal, the form of the impulse transition function changes due to nonlinear distortion. The difference of the pulse transient functions, which characterizes the nonlinear distortion, is calculated in the subtraction unit 15, and the result of the subtraction after the square in block 16 and averaging in block 17 enters the registration unit 18.

Eliminating the need to have an auxiliary recording channel during measurement

The completeness is mutually correlated with the reproduced test signal, and after separation the signal of a higher level is delayed.

Sources of information taken into account in expert opinion:

1. USSR author's certificate

No. 307356, M.C.L. q 01529/04.22.09.69.

2. USSR author's certificate

No. 356597, M.C.QO1R 29 / 02,19.02.71.

Claims (1)

3. Authors certificate of the USSR №261576 M. Cl. Q01R 29/02, 07/12/68 (prototype). a strong signal allows for improved measurement accuracy. The invention of the method for measuring non-linear distortions in magnetic recording equipment by recording and reproducing reference and test signals, the last of which is recorded at higher and lower levels, separation when reproducing the test signal into signals of higher and lower levels, reducing the separated signals to a constant the magnitude and subsequent measurement of nonlinear distortion by the difference of the above signals, characterized in that, in order to improve the measurement accuracy, the recording is formed from a test signal in the form of a pseudo-random binary sequence, and higher and lower recording levels alternate, and, moreover, when playing before the level separation, the reference signal is delayed, a pseudo-random binary sequence is formed from the delayed signal, then this successor