Circuit for transmitting video signal of two-wire system video door phone system
A technology of intercom system and video signal, which is applied in the direction of cable transmission adaptation, two-way working system, TV, etc. It can solve the problems of unbalanced video signal signal, narrow transformer coupling frequency bandwidth, and inability to eliminate signal bus interference, etc., to achieve enhanced anti-corrosion disruptive effect
Inactive Publication Date: 2016-04-06
GUANGZHOU VIDEO STAR ELECTRONICS
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Problems solved by technology
[0003] Through the transformer coupling method, although the impedance matching and primary-secondary isolation can be well realized, the video signal on the bus is an unbalanced signal, which cannot eliminate the interference in the signal bus transmission process, and it is necessary to add a filter to the indoor unit to monitor the video signal. Filtering; and the frequency bandwidth of transformer coupling is relatively narrow
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[0040] The invention provides a video signal transmission circuit for a two-wire video intercom system, which can effectively perform balanced and unbalanced conversion processing on the video signal, thereby improving the anti-interference performance of the video signal.
[0041] see figure 1 , a circuit embodiment for video signal transmission of a two-wire video intercom system in an embodiment of the present invention, including:
[0042] A first resistor R1 and a first capacitor C1 for coupling the video signal, and the video signal passes through the first resistor R1 and the first capacitor C1 in sequence;
[0043] The other end of the first capacitor C1 is connected to the first common mode inductor T1.
[0044] Among them, the common-mode inductor constitutes a balun transformer, which performs balanced-unbalanced conversion of the video signal, so that the video signal is a balanced signal on the two-wire bus, and the anti-interference performance of the signal is ...
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The invention discloses a circuit for transmitting a video signal of a two-wire system video door phone system. According to the circuit, the video signal can be effectively subjected to balance and unbalance conversion processing, so that anti-interference performance of the video signal is improved. The circuit for transmitting the video signal of the two-wire system video door phone system, which is provided by the invention, comprises a first resistance R1 and a first capacitance C1 which are used for coupling the video signal, wherein the video signal sequentially passes through the first resistance R1 and the capacitance C1; and the other end of the first capacitance C1 is connected with a first common mode choke T1.
Description
technical field [0001] The invention relates to the field of electronic circuits, in particular to a circuit for video signal transmission of a two-wire video intercom system. Background technique [0002] In the two-wire video intercom system, the method of transformer coupling is generally adopted. The VTO loads the modulated video signal to the two-wire bus through transformer coupling; the indoor unit takes out the modulated video signal from the two-wire bus through transformer coupling. [0003] Through the transformer coupling method, although the impedance matching and primary-secondary isolation can be well realized, the video signal on the bus is an unbalanced signal, which cannot eliminate the interference in the signal bus transmission process, and it is necessary to add a filter to the video signal in the indoor unit. Filtering; and the frequency bandwidth of transformer coupling is relatively narrow. [0004] Therefore, it is urgent to provide a video signal ...
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IPC IPC(8): H04N7/10H04N7/14
CPCH04N7/10H04N7/141
Inventor 朱湘军彭永坚黄培周
Owner GUANGZHOU VIDEO STAR ELECTRONICS