SU932650A1 - Device for reproducing television signal - Google Patents

Description

The invention relates to television technology and can be used in communication systems in the reduced frequency band. A device for reconstructing a television signal is known, comprising a balanced modulator, the first input of which is connected to the video source and the first input of the first adder, the second input of which is connected to the output of the balanced modulator, the output of the first adder is connected to serially connected low-pass filter and the second adder, the output of which is connected to the first input of the third adder and to the input of the delay line for the duration of the line, the output of the delay line is connected to the second inputs of the second and three rd adders pj. However, the known device for recovering a television signal has insufficient noise immunity. The purpose of the invention is to improve noise immunity. This goal is achieved by the fact that a device for restoring a television signal containing a balanced modulator, the first input of which is connected to a video source and the first input of the first adder, the second input of which is connected to the output of a balanced modulator, the output of the first adder is connected to a series-connected filter low frequency and the second adder, the output of which is connected to the first input of the third adder and to the input of the delay line for the duration of the line, entered the fourth adder, n m adder, four delay lines for the duration of the decomposition element, the first input of the fourth adder is connected to the output of the delay line for the duration of a% line and to the input of the first delay line for the duration of the decomposition element, and the second input of the fourth adder is connected via serially connected first and second lines delays for the duration of the decomposition element, the common connection point of which is connected to the second input of the third adder, the output of the fourth adder is connected to the second input of the second totalizer Ora, the output of the third adder is connected to the first input of the fifth adder and serially connected third and fourth delay lines for the duration, decomposition element, the outputs of which are connected to the second and third inputs of the fifth adder respectively. FIG. Figure 1 shows the electrical circuit diagram of a device for recovering a television signal; in fig. 2 - normalized amplitude characteristic of the comb filter. The device for reconstructing the viewing signal bodies comprises a balanced modulator 1, a first adder 2, a low-pass filter 3, a second adder, a delay line 5, a third adder 6, a fourth and fifth adders 7 and 8, the first, second third and fourth lines 9- 12 delays for the duration of the decomposition element. 2 Ico V-l- () where Т-; :: line-scan period; the duration of the decomposition element. The normalized ridges of the characteristics (1) corresponding to the different harmonic numbers of the horizontal frequency K are shown in FIG. 2. The absolute values of the transmission coefficient at the frequencies (and 2 THGP (, ur, multiple of the horizontal scanning frequency, can be obtained on the basis of (1 hflQX -1h-1.,

The correction circuit, consisting of the third and fourth delay lines 11 and 12 for the duration of the decomposition element and the fifth adder 8, has a transmission coefficient () which is relative to C2)

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invention formula

A device for reconstructing a television signal containing a balanced modulator, the first input of which is connected to a video source. 4 A device for reconstructing a television signal works as follows. The signal received in the reduced frequency band is fed to the balanced modulator 1. In the first adder 2, the converted signal is added to the received. As a result, the transmitted signal is all set in the full frequency band. Along with the useful signal, the output of the low pass filter 3 is interleaved with a crushing interference. The selection of the useful signal is carried out by a comb filter including a delay line 5, a feedback circuit and a second and third adders 4 and 6. A distinctive feature of the comb filter is the frequency-dependent feedback circuit comprising the first and second delay lines 9 and 10. for the duration of the decomposition element and the fourth accumulator 7. The feedback circuit transfer ratio varies from - Epyukh 43 zero frequency to + (b (/ ic |) at the upper bound frequency of the video signal spectrum. At this amplitude-frequency characteristic This comb filter is described by the expression CCKitut-.coS tf t, thereby achieving a uniform envelope of the resulting amplitude-frequency response of the regenerating filter. It is not possible to effectively suppress interference in the full frequency band with the least loss of the useful signal. Due to this, the best quality of the received image is achieved.

signal and the first input of the first adder, the second input of which is connected to the output of the balanced modulator, the output of the first adder is connected to the series-connected low-pass filter and the second adder, the output of which is connected to the first input of the third adder and to the input of the delay line for the duration of the line, distinguishing This is due to the fact that, in order to improve noise immunity, a fourth adder, a fifth adder, four delay lines for the duration of the decomposition element have been entered into it, the first input of the fourth with mmatora connected to the output of the delay line and the length of line to the input of the first delay line of the length decomposing element, and a second input of the fourth adder is connected via

serially connected first and second lines of delay for the duration of the decomposition element, the common connection point of which is connected to the second input of the third adder, the output of the fourth adder is connected to the second input of the second adder, the output of the third adder is connected to the first input of the fifth adder and serially connected by the third and fourth line delays for the duration of the decomposition element, the outputs of which are connected respectively to the second and third inputs of the fifth adder.

Sources of information taken into account in the examination

1. Suslonov S.A. et al. Study of a television system with a reduced frequency band. - Technique of cinema 1 television, 1967 No. 3.

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Claims (1)

Claim A device for recovering a television signal containing a balanced modulator, the first input of which is connected to the video source _{(3) of the} signal and to the first input of the first adder, the second input of which is connected to the output of the balanced modulator, the output of the first adder is connected to a low-pass filter and a second adder connected in series , the output of which is connected to the first input of the third adder and to the input of the delay line for a line duration, characterized in that, in order to increase the noise immunity, enter The fourth adder, the fifth adder, four delay lines for the duration of the decomposition element are provided, and .15 the first input of the fourth adder is connected to the output of the delay line for the line length and to the input of the first delay line for the duration of the decomposition element, and the second input of the fourth fourth adder is connected through series-connected first and second lines · delays for the duration of the decomposition element, the common connection point of which is connected 5 to the second input of the third adder, the output of the fourth adder is connected n to the second input of the second adder, the output of the third adder is connected to the first input of the fifth adder and to the third and fourth delay lines for the duration of the decomposition element, the outputs of which are connected respectively to the second and third inputs of the fifth adder.