SU785895A1 - Method and device for compensating for magnetic carrier motion speed fluctuations at multichannel reproducing of pulse-modulated signals - Google Patents

Description

of the adjacent channel, the difference of the uncompensated signals of each and the subsequent channels, while the compensated value of the signal of the first channel is calculated by subtracting the difference of the uncompensated signals of the first and second channels from the uncompensated signal of the previous channel.

A device for carrying out this method is provided in each channel with two subtractors, the first input of the first subtracting unit of each channel is connected to the input of the same channel and through the second descent of the first subtraction unit of the previous channel to the first input of the second subtraction unit of the corresponding channel, the output of which is connected to the output of this channel and the second input of the second subtraction unit of the subsequent channel.

In addition, in order to compensate for signals with a constant component, a pulse generator and a switch with double closing and opening contacts are inserted into the device, with two closing contacts connected in series to the input circuit of the first channel, and the output of the pulse generator is connected to the first through the closing contacts of the switch the input of the first subtraction unit.

As a result of the mutual subtraction of the durations of the reproduced pulse-modulated signals, a difference of durations is obtained, in which there is no error in duration caused by fluctuations in the speed of the magnetic tape and the same for all channels, after repeated subtraction, the useful signal duration of each channel is also not containing the specified error. Due to the absence of the need to record a special reference signal, the specific recording density increases, the information recording device is simplified.

The drawing shows a device for compensating for fluctuations in the speed of movement of a magnetic tape during multichannel playback.

The device contains N inputs li, g, ... ..., and, ..., n, the first subtraction blocks 2L-2, the second subtraction blocks 3 (-SN and outputs 4i-4c, where N is the number of playback channels, a pulse generator 5 of a predetermined duration and a switch 6 with dual closing contacts 7 and opening contacts 8.

The compensation for oscillations of the speed of the magnetic tape is carried out as follows.

When playing pulse-modulated signals with a variable pulse frequency from the pulse duration of the first channel using the first

subtraction unit 2 subtracts the pulse width of the 2nd channel.

: i1 -tig.to (1t ,,) - io (.),

where to - unmodulated duration

impulse;

“(MtTi2.- useful modulation; e, dd2.- errors due to speed fluctuations;

Moreover, AI, etc., i.e.

the effect of carrier velocity fluctuations on

0 two adjacent impulses approximately

the same, then tm -tut t o (tn, - tno) This duration does not contain a fault,

caused by the speed of the carrier,

but does not contain a useful signal, but only

difference in duration of useful signals

first and second channels.

After the second subtraction block we get

to (1 + tn ,,) to (.- Tni) to (l niifAi)

This expression is nothing other than the value of the signal of the second channel, but without the error of this channel. In this expression, the error value of only the first channel D i is repeated. After the first block subtracting the second channel

J tKi. (. T-Ai.) - to () to (mj.-nij) and

further after the second block

iю (1 tt1i + D,) - to (mg.-nlе) tв (()

And so on, i.e., producing a similar subtraction for the subsequent channels, eliminates the errors of carrier speed fluctuations in the signals of all channels and obtains compensated signal values.

The error Ai is a constant component, due to the use of another pulse-modulated signal of a random duration that does not coincide with the duration to as a reference signal for this channel. This error may be disregarded when recording reproduction of pulse signals modulated by useful information that does not have a constant component, such as control signals of static systems.

To eliminate the error of transmission of the constant component, in necessary cases, a pulse generator 5 is used, connected with the help of dual contacts 7 and 8 of switch 6 to the first input of the first block of the first subtraction channel b. By briefly pressing the switch b, the output of the generator 5 is connected via the contact contacts .7 with the first input of the first subtraction unit, simultaneously with the help of the disconnecting contacts 8 the playback channel is disconnected. At the same time, the first input of the li unit is received from the generator 5 with pulses of duration to and the setting of the mode of compensation of the oscillations of the speed of the tape movement occurs, in which there is no constant error A. The maximum time for setting this mode is equal to the duration of the pulse of the pulse-modulated signal, arriving in this case at the first input 1o of the first channel.

Using the proposed method of compensating for fluctuations in the speed of movement of a magnetic tape during multichannel playback and a device for its implementation provides an increase in the specific recording density of useful information by a factor of 2.

Claims (3)

Invention Formula . A method for compensating fluctuations in the speed of movement of a magnetic carrier during multichannel reproduction of pulse-modulated signals, based on subtracting the durations of signals from different channels and then converting the resulting difference, characterized in that, in order to increase the recording density by using information signals as reference signals, the compensated value of each signal channel is obtained by subtracting from the compensated signal of the previous adjacent channel the difference of the non-compensated OF DATA signals and each subsequent channel, wherein the compensated value of the first signal The channels are determined by subtracting from the uncompensated signal of the previous channel the differences in the uncompensated signals of the first and second channels. 2. An apparatus for carrying out the method according to claim 1, characterized in that each channel is provided with two subtraction units, wherein the first input of the first subtraction unit of each channel is connected to the input of the same channel and through the second input of the first subtraction unit of the previous channel the first input of the second subtraction unit of the corresponding channel, the output of which is connected to the output of this channel and to the second input of the second subtraction unit of the subsequent channel. 3. The device according to claim 2, characterized in that, in order to compensate for signals with a constant component, a pulse generator and a switch with double closing and opening contacts are inserted into it, and two opposite contacts of the switch are connected in series to the input circuit of the first channel, and the output of the pulse generator through two closing contacts of the switch is connected to the first input of the first subtraction unit. Information sources, taken into account in the examination 1. USSR author's certificate number 487412, cl. G 11 B 5/00, 05.10.75. 2. USSR author's certificate No. 404124, cl. G 11 5/04, 10.05.72 (prototype).