SU1385326A1 - Synchroselector - Google Patents

Abstract

This invention relates to a TV technology and increases noise immunity. The device contains a transition capacitor 1, keys (k) 2, 9 and 10, KOMija- rator 3, voltage divider (DN) 4, containing capacitor 5 and resistors 6 and 7, diff. block 8 and resistor 11. To achieve the goal, the 1st and 2nd outputs of block 8 are connected to the control inputs K 2 and 9, respectively, and the output K 10 is connected to the input of DN 4. The device retains its efficiency at the condition Uj, I / 2; and „, i.e. when I uUn I and. which is twice the corresponding value for dl; the prototype, the scale of the sync pulses, the di is the increment of the value of the additive noise during the horizontal scanning period. 2 Il.

Description

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The invention relates to television technology and can be used as part of receiving, measuring and other television equipment.

The purpose of the invention is to improve the noise immunity.

Figure 1 shows the structural electrical circuit of the sync selector; 2 shows timing diagrams for his work.

The sync selector (FIG. 1) contains a transition capacitor 1, a first switch 2, a comparator 3, a voltage divider 4 comprising a capacitor 5 and first and second resistors 6 and 7, a differentiating unit 8, a second switch 9, a third switch 10, and a resistor 11.

The sync selector works as follows.

The input video signal affected by low-frequency interference (FIG. 2p) is fed to the first input of the comparator 3 via a capacitor 1, termed the constant component (FIG. 26), which is restored at the moment of closing the second key 9. It is clear that when the key 9 is first activated (time t) binding is incorrect. In this case, the constant component of the video signal is reduced. But during the appearance of a pulse at the first output of the differential unit 8, the negative voltage is applied to the input of the voltage divider A, which charges the capacitor 5. At the same time, while the output of the comparator 3 is signal O (Fig. 2c), the voltage at the second input of the comparator 3 due to the closure of the third key 10 close to the input voltage of the divider 4 voltage. Therefore, the second key 9 is turned on for the second time at time tj, i.e. when the voltage at the second output of the capacitor 1 is negative, which leads to an increase in the constant component of the video signal at the first input

comparator 3. The described process is pro- 50 that, in order to increase the noise immunity, the first and second codes of the differentiating unit are connected respectively to the control inputs of the first and second keys, and the output 55 of the third probe is connected to the input

lasts until the first key 2 closes at the beginning of the vertices of the horizontal sync pulses (time t, tg, figd), and the second key 9 - at the beginning of the rear quenching horizontal sync pulses (the time t, t,

divider voltage.

Fig. 2d). Such a mode of operation of the sync selector is steady-state.

In the proposed sync selector, the first key 2 connects the input of the sync selector to the voltage divider 4 before passing the pulses that fix the television signal to the zero potential. Therefore, the divider 4 remembers the voltage Id (Fig. 2B).

Ide / Cn + and. (1) After that, the video signal is fixed by the damping pad to the potential of the common ground. At the output of the voltage divider, a voltage is generated. Part 2 2

with,

(2)

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Obviously, the proposed sync selector maintains its operability under the condition

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that double

is the corresponding value for the known device, where U ,, is the sweep of the sync pulses; uUq is the increment of the value of additive interference over the horizontal scanning period.

Claims (1)

Invention Formula A sync selector containing a transition capacitor, whose input is a video signal input, and an output connected to the information inputs of the first and second keys and to the first input of a comparator, the output of which is the output of the sync selector and connected to the input of the differentiating unit and the control input of the third key the input of which through a resistor is connected to the second input of the comparator and to the first output of the voltage divider, the second output of which is connected to the output of the second key and to the common bus, and the input to the output of the first key is different yuschiys. topics divider voltage. t 3ttfts (J3ue. 2 tet7