SU970458A1 - Device for checking relative level of signal penetration from one channel of stereo tape-recorder to another - Google Patents

Description

The invention relates to a technique of magnetic recording, in particular to a device for controlling stereo recorders. A device for monitoring the relative level of signal penetration from one stereo recorder to another, containing a sinusoidal signal generator, a resistor and a selective voltmeter alternately connected to the outputs of a stereo tape recorder is known. A disadvantage of this device is the need for multiple selective voltmeter frequency tuning when measuring the relative level of penetration the recorded signal from one channel of a stereo recorder to another at several frequencies. The closest in technical essence and the achieved effect to the invention is a device for monitoring the relative level of signal penetration from one stereo tape recorder to another, containing a control signal generator, a set of band-pass filters, a set of resistors and a voltmeter alternately connected to the outputs of the band-shaped voltmeters 2. The second device, although to a lesser extent, has the same drawback as the first one, because in the control process the operator must make a large number of connections of resistors and the generator output in a predetermined sequence to match the inputs of the tested stereo recorder, change the frequency. And the amplitude of the control signal, alternately connect a voltmeter to the outputs of various 4n1, and read voltmeter readings and perform the necessary calculations. The process of controlling with the help of a known device is laborious. The purpose of the invention is to reduce the time and simplify the control process. The goal is achieved by introducing a second set of bandpass filters, a set of amplifiers, the first, second and third switches, an oscilloscope, a program block, the first and second sets: rectifiers and a generator of control pulses, the first output of which is connected to the control input of the third switch, the second / output - to the synchronization input of the oscilloscope, and the third - to the input of the oscilloscope beam intensity modulation, the signal input connected to the third switch in turn, to the inputs of which the switches are connected respectively to the outputs of all the mentioned switches, the inputs of which are respectively connected to the outputs of the band-pass filters, the inputs of the band-pass filters of one of the sets are respectively connected to the outputs of the amplifiers, the combined inputs of which are connected to one of the outputs of the second. switch, to the other output of which the combined inputs of the i-th filters of the other set are connected, while the control input of the second switch is connected to the first output of the program block, to the second output of which is connected the control input of the generator of control signals, the output of which is connected to one of the inputs of the first switch, the remaining inputs of which are connected to the outputs of a set of resistors, in addition, the third output of the program block is connected to the control input of the first switch. FIG. 1. shows the functional diagram of the proposed device; in fig. 2 - oscillogram of the output signals of the device for the case of monitoring the relative penetration level of the signal, consisting of the sum of three signals, of different frequencies. The device contains a generator of 1 control signals and a set of 2 resistors. 3 connected to the inputs of the first switch 4, the outputs of which are connected to the corresponding inputs of the tested stereo tape recorder 5. The number of resistors 3 is equal to the number of pairs of stereo inputs of the tape recorder 5, and the number of Outputs of the first switch 4 is equal to the total number of stereo inputs of the tape recorder 5. The outputs of the tested stereo tape recorder 5 should be sue j. to the corresponding inputs of the second switch 6, the first output of which is connected to the combined inputs of the set 7 8 .. ,,. Here and amplifiers 8, 8, then n is equal to the number of harmonic components of the signal generator 1. The outputs of the amplifiers 8 are connected to the corresponding inputs of a set of band-pass filters 10 - ,, lOv), ..., 10 n The second output of the switch 6 is connected to the combined inputs set of 91 band-pass filters 10.p +, -1-Op + 2. The outputs of all bandpass filters 10 are connected to the corresponding inputs of rectifier sets And-, and 11 j, .f 12.2, ..., .12.1 and i2n g 12p + 2 Outputs of all rectifiers. 12. connected to the corresponding entrances of the third switch 13, the output of which is connected to the signal input of the oscilloscope 14, and the control input of the switch 13 to the output of the generator 15 of control pulses, the other two outputs are connected respectively to the synchronization and brightness modulation inputs of the oscilloscope 14 The outputs of program block 16 are connected respectively to the control inputs of the generator 1 of control signals, the first switch 4 and the second switch 6. The device operates as follows. . Before starting work, using recording level controllers (not shown in Fig. 1) set the nominal recording level in each channel of the tape recorder 5 to be tested. Then, using the program block 16, select the operating mode of the device. In the mode of controlling the relative level of signal penetration from the left channel of the tested tape recorder 5 into the right channel, using the program block 16, one of the inputs of the left channel of the tape recorder 5 is sent through the first switch 4 from generator 1, which is a sum n of harmonic signals having the same amplitude, but different frequencies. To the input of the right channel of the tape recorder 5, through the switch 4, one of the resistors 3 of the set 2 is connected with a resistance equal to the nominal electrical resistance of the signal source for this input. The second switch 6. in this mode of operation of the device using the program block 16 connects the output of the left cable of the stereo recorder 5 to the inputs of a set of 9 band-pass filters lOfi-ft, / I and the output of the right channel to the inputs of a set of 7 amplifiers 8, 6, ... , bp Thus, in the indicated mode of operation of the device, a multi-frequency signal from generator 1 is recorded in the left channel of the stereo recorder 5 under test and the signal penetrated into this channel through the parasitic connections in the right channel. At the end of the recording, the recorded sections are reproduced, and the multi-frequency signal from the output of the left channel of the tape recorder 5 passes through the second switch.6 to the inputs of the iQif bandpass filters, 4-t I lO nlZ g lOrj-p set, by which it is divided into separate the harmonic components and rectifies the corresponding drivers on sets 12 and ll to obtain the DC levels. & the current signal of the right channel of the tested stereo recorder 5, also representing a combination of the harmonic components of the signal penetrated from the left channel, after amplification by the corresponding amplifiers 8 of the set 7,

It enters the inputs of the band-pass filters 10, 10, ..., 10p of kit 9 for dividing into separate harmonic components and is rectified by the corresponding rectifiers 12 of kit 11. The pairs of band-pass filters 10 and 10 ". , 10 and, ..., 10c and 101 have the same center frequencies, the passbands equal to the frequencies of the corresponding harmonic components of the pilot signal. Information about the relative level of penetration from the left channel of the recorder 5 into the right channel is contained in the ratio of the levels of direct voltage and the outputs of the corresponding rectifiers 12. In the proposed device, the transmittance of amplifiers 8, Q, f ..., 8rit of band-pass filters 10.), 10, ..., 10.2p and the rectifiers 12, 12, ... r12 "are chosen in such a way that the maximum permissible relative level of penetration from the left channel of the stereo recorder 5 into the right corresponds to the equality of the voltages at the outputs of the corresponding rectifiers 12 n boron 11 and 11. Signals from vEShr tifiers both sets 12, due to control signal generator 15, are coupled alternately -tert switch 13 to the signal input of the oscilloscope. 14. In FIG. Figure 2 shows one of the possible oscilloscopes of the oscilloscope formed on the screen 17 14. The heights of the marks 17-20 on the screen 17 are proportional to the levels of the corresponding harmonic components of the pilot signal at the output of the right channel of the tape recorder 5, and the heights of the corresponding marks 21-23 are proportional to the levels of the corresponding signals the harmonic components of the control signal at the output of the left channel of the tested tape recorder 5. The relative level of penetration from the left channel of the tape recorder 5 into the right channel does not exceed the maximum permissible values on none of the three frequencies, i.e. is in the specified tolerance field, if label 18 is not Btane label 21, label 19 is not higher than label 22, but label 20 is not higher than label 23. Tags 24 and 25 are induced at those times when the third switch 13 connects the oscilloscope signal input 14 to the common wire of the device. In the mode of controlling the relative level of signal penetration from the right channel of the tested stereo recorder 5 into the left channel using the BLOCK 16 program and switches 4 and 5, the output of the control signals generator 1 to the input of the right channel of the tape recorder 5 corresponding to the resistor 2 is connected to the left input channel output

the left channel of the tape recorder under test to the inputs of amplifiers 8 of the set 7, and the output of the right channel to the inputs of the band-pass filters 10 of the set 9. The further operation of the device in this mode does not differ from its operation in the mode described above.

The invention makes it possible to control the relative level of penetration of a signal from one kangsha to another in the end-to-end mode of operation of the tested stereo recorder simultaneously on several frequencies. I -; ,

15

The use of the invention will allow to speed up the process of control by 3-5 times, as well as to use less qualified operators for this operation.

20

Claims (2)

1. Household tape recorders. Test methods and measurements. GOST 17162-71. 2. Household tape recorders. The main pars1metry. Technical requirements Measurement methods. ST SEV 1359-78. (prototype). "/G./ nineteen TO 15 fig