CN106657715B - Vehicle-mounted analog video signal anti-interference system - Google Patents
Vehicle-mounted analog video signal anti-interference system Download PDFInfo
- Publication number
- CN106657715B CN106657715B CN201611075564.7A CN201611075564A CN106657715B CN 106657715 B CN106657715 B CN 106657715B CN 201611075564 A CN201611075564 A CN 201611075564A CN 106657715 B CN106657715 B CN 106657715B
- Authority
- CN
- China
- Prior art keywords
- resistor
- capacitor
- camera
- operational amplification
- analog video
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/14—Picture signal circuitry for video frequency region
- H04N5/21—Circuitry for suppressing or minimising disturbance, e.g. moiré or halo
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/18—Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention relates to a vehicle-mounted analog video signal anti-interference system, which comprises a camera and a display module which are connected with each other; a differential operational amplification interface circuit is arranged in the display module, and the camera is connected with the input end of the differential operational amplification interface circuit; a low-pass filter circuit is arranged in the display module and is connected with the output end of the differential operational amplification interface circuit; the power ground of the camera is connected with the power ground of the display module. The analog video signal line output by the camera of the vehicle-mounted analog video signal anti-interference system is connected to the differential interface circuit of the display module, and the ground loop disappears. The camera is directly connected to the display module through a power supply ground, so that the reference ground potential difference between the two modules is small enough, the two modules cannot be influenced by other modules, and the display effect is not influenced any more. After the analog video signal passes through the OPA circuit, the high frequency interference on the analog video signal, which is present due to the implicit loop, is filtered out by a low pass filter. Thereby improving the anti-interference capability of the analog video signal.
Description
Technical Field
The invention relates to the technical field of automobile electronics, in particular to a technical scheme design for anti-interference of an analog video signal of an automobile sound entertainment system.
Background
The invention mainly aims at the design of an anti-interference circuit for analog video signals of an automobile sound entertainment system. In recent years, automobile sound entertainment systems are developed rapidly, reversing images are no longer patents of cars above middle-high-end cars, reversing image systems are also configured on some small-sized cars and micro-passengers, and therefore consumers with more commercial purposes experience the convenience brought to reversing and entering parking spaces by scientific and technological configuration. With the increasing control requirements of the whole automobile factories on the cost of automobile parts and the better display effects, the existing designs must be improved to meet the requirements of customers.
The design schemes of the transmission circuit of the backing image system commonly used at present are as follows:
the display module and the reversing camera transmit video signals in a balanced circuit mode. If two conductors and the circuit to which they are connected have the same impedance relative to ground or other circuit reference point, the circuit is referred to as a balanced circuit. It is difficult to fully balance any circuit at high frequencies because of the large number of spurious parameters in a real circuit that have a large effect on the impedance of the circuit. Due to the uncertainty of these stray parameters, the impedance of the circuit is also uncertain, and it is difficult to ensure that the impedances of the two conductors are identical. Therefore, the requirement on the transmission cable is high, and the cost of the reversing image system is greatly increased. With the wider and wider application of commercial cameras, cameras with unbalanced CVBS video signal output have become the mainstream of the market. The whole car factories increasingly adopt cameras of unbalanced CVBS video signal output.
The display module and the reversing camera transmit video signals in an unbalanced circuit mode (as shown in figure 1). The requirement of the unbalanced transmission mode on the cable is greatly reduced. But a large ground loop is formed due to the signal lines CVBS-connected to the display module GND2 and the camera GND3, respectively. The difference in potential of the two grounding points (GND 2 and GND 3) (caused by the display module operating current I1, which now becomes more and more functional, sometimes I1 even exceeds 10A) and the alternating electromagnetic field in the environment all form a current I2 in the loop. Resulting in a potential difference V1 between the display module and the camera reference ground. If V1 contains components within the frequency bandwidth of the analog video signal, it will interfere with the video signal and cannot be filtered out, directly affecting the display effect, and having poor user experience. A common solution is to add a common mode choke coil to the camera head end, and increase the impedance of the ground loop to reduce the ground loop current, thereby reducing the influence of the ground loop current. The larger the inductance of the common mode choke, the better the effect of the common mode choke and the larger the size of the choke. The camera is small in size, the common mode choke coil is limited, and inductance cannot be achieved to be large. In extreme cases, the user may still experience fluctuations in the display.
Disclosure of Invention
The invention aims to provide a vehicle-mounted analog video signal anti-interference system capable of effectively improving the anti-interference capability of an analog video signal.
In order to solve the technical problem, the vehicle-mounted analog video signal anti-interference system comprises a camera and a display module which are connected with each other; a differential operational amplification interface circuit is arranged in the display module, and the camera is connected with the input end of the differential operational amplification interface circuit; a low-pass filter circuit is arranged in the display module and is connected with the output end of the differential operational amplification interface circuit; the power ground of the camera is connected with the power ground of the display module; wherein the differential operational amplification interface circuit comprises: the operational amplifier is connected with the camera; a filter circuit connected between a power supply and the operational amplifier; the low-pass filter circuit includes: the circuit comprises a resistor R10, an inductor L1 and a capacitor C9 which are sequentially connected in series, wherein one end of the resistor R10 is connected with the output end of the operational amplifier; and one end of the capacitor C8 is connected between the capacitor C9 and the inductor L1, and the other end of the capacitor C8 is grounded.
The operational amplifier includes: one end of the resistor R10 is connected with the output end of the operational amplification chip; one end of the resistor R4 is connected with the inverting input end of the operational amplification chip; one end of the resistor R5 is connected with the positive phase input end of the operational amplification chip; one end of the resistor R6 is connected with one end of the resistor R4, and the other end of the resistor R6 is connected with the output end of the operational amplification chip; the resistor R7 and the resistor R8 are connected in series, one end of the resistor R7 is connected with a power supply end of the operational amplification chip, and the resistor R8 is grounded; the two ends of the capacitor C1 are respectively connected with the positive phase input end and the negative power end of the operational amplification chip; and one end of the capacitor C7 is connected with the inverting input end of the operational amplification chip, and the other end of the capacitor C7 is connected with the output end of the operational amplification chip.
The filter circuit includes: the circuit comprises a resistor R9 and a capacitor C5 which are connected in series, wherein one end of the resistor R9 is connected with the power supply, one end of the capacitor C5 is grounded, and a positive power supply end of the operational amplification chip is connected between the resistor R9 and the capacitor C5; and one end of the capacitor C6 is connected between the capacitor C5 and the resistor R9, and the other end of the capacitor C6 is grounded.
The anti-interference system of the vehicle-mounted analog video signal further comprises: the camera comprises a resistor R1 and a capacitor C3 which are connected in series, wherein one end of the resistor R1 is connected with a signal negative phase output end of the camera, and one end of the capacitor C3 is connected with the other end of the resistor R4; the camera comprises a resistor R2 and a capacitor C2 which are connected in series, wherein one end of the resistor R2 is connected with a signal positive phase output end of the camera, and one end of the capacitor C2 is connected with the other end of the resistor R5; the resistor R3, the one end of resistor R3 is connected the resistor R1 with between the electric capacity C3, the other end of resistor R3 is connected the resistor R2 with between the electric capacity C2.
The operational amplification chip is TI OPA354.
The analog video signal line output by the camera of the vehicle-mounted analog video signal anti-interference system is connected to the differential interface circuit of the display module, and the ground loop disappears. The camera is directly connected to the display module through a power supply ground, so that the reference ground potential difference between the two modules is small enough, the two modules cannot be influenced by other modules, and the display effect is not influenced any more. After the analog video signal passes through the OPA circuit, high frequency interference on the analog video signal due to the implicit loop is filtered out by a low pass filter. Thereby improving the anti-interference capability of the analog video signal.
Drawings
Fig. 1 is a schematic diagram of the prior art.
Fig. 2 is a schematic diagram of the anti-interference system for the vehicle-mounted analog video signal.
Fig. 3 is a circuit diagram of a low-pass filter circuit and a differential operational amplifier interface of the anti-interference system for vehicle-mounted analog video signals.
Detailed Description
The following describes the anti-interference system for vehicle-mounted analog video signals in further detail with reference to the accompanying drawings.
As shown in figures 2 and 3, in the anti-interference system for the vehicle-mounted analog video signal, the display module interface circuit is a differential operational amplification interface circuit, a CVBS-is not connected to GND2 any more, a ground loop is cut off, and loop current cannot be generated. In addition, the GND3 of the camera is directly connected to the GND2 of the display module, so that the display effect is not influenced due to the fact that the working current of the display module is large and the display module is inconsistent with the ground potential of the whole vehicle. And the current of the camera is very small (and I3 is very small), so that the potential difference V2 between the camera and the display module is small enough. However, this single point grounding approach does not work well if the frequency of the interference is high, because although there is no apparent ground loop, there is an implicit ground loop due to stray capacitance. Therefore, the design adds a low-pass filter circuit after the OPA circuit to filter out these higher frequency interference signals.
The low-pass filter circuit includes: the circuit comprises a resistor R10, an inductor L1 and a capacitor C9 which are sequentially connected in series, wherein one end of the resistor R10 is connected with the output end of an operational amplifier; and one end of the capacitor C8 is connected between the capacitor C9 and the inductor L1, and the other end of the capacitor C8 is grounded.
The operational amplifier includes: one end of the resistor R10 is connected with the output end of the operational amplification chip; one end of the resistor R4 is connected with the inverting input end of the operational amplification chip; one end of the resistor R5 is connected with the positive phase input end of the operational amplification chip; one end of the resistor R6 is connected with one end of the resistor R4, and the other end of the resistor R6 is connected with the output end of the operational amplification chip; the resistor R7 is connected with the resistor R8 in series, one end of the resistor R7 is connected with a power supply end of the operational amplification chip, and the resistor R8 is grounded; two ends of the capacitor C1 are respectively connected with a positive phase input end and a negative power end of the operational amplification chip; and one end of the capacitor C7 is connected with the inverting input end of the operational amplification chip, and the other end of the capacitor C7 is connected with the output end of the operational amplification chip.
The filter circuit includes: the circuit comprises a resistor R9 and a capacitor C5 which are connected in series, wherein one end of the resistor R9 is connected with a power supply, one end of the capacitor C5 is grounded, and a positive power supply end of an operational amplification chip is connected between the resistor R9 and the capacitor C5; and one end of the capacitor C6 is connected between the capacitor C5 and the resistor R9, and the other end of the capacitor C6 is grounded.
The vehicle-mounted analog video signal anti-interference system further comprises: the camera comprises a resistor R1 and a capacitor C3 which are connected in series, wherein one end of the resistor R1 is connected with a signal negative phase output end of the camera, and one end of the capacitor C3 is connected with the other end of a resistor R4; the camera comprises a resistor R2 and a capacitor C2 which are connected in series, wherein one end of the resistor R2 is connected with the signal positive phase output end of the camera, and one end of the capacitor C2 is connected with the other end of a resistor R5; one end of the resistor R3 is connected between the resistor R1 and the capacitor C3, and the other end of the resistor R3 is connected between the resistor R2 and the capacitor C2.
R1, R2 and R3 are subjected to voltage division according to the requirement of the AD converter on the amplitude of the input signal, and together form a terminal matching resistor of the analog video signal. R9, C5 and C6 form a filter circuit on the operational amplifier power supply. C2, C3 and C9 are blocking capacitors of the circuit and block direct current components on the circuit. R4, R5, R6, R7, R8, C1, C7 and IC1 form an operational amplifier circuit, and the reference ground CVBS-of the input analog video signal is converted into the display module reference ground GND 2. R10, L1 and C8 form a low-pass filter for filtering high-frequency interference components in the video analog signal. Through the operational amplifier circuit, the CVBS-signal does not need to be connected to GND2, and a ground loop is cut off; and a low-pass filter is added to filter out high-frequency interference signals in the analog signals. The anti-interference capability of the analog video signal is improved.
While the preferred embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that the invention is not limited thereto, and that various changes and modifications may be made without departing from the spirit of the invention, and the scope of the appended claims is to be accorded the full scope of the invention.
Claims (5)
1. The vehicle-mounted analog video signal anti-interference system is characterized by comprising a camera and a display module which are connected with each other;
a differential operational amplification interface circuit is arranged in the display module, and the camera is connected with the input end of the differential operational amplification interface circuit;
a low-pass filter circuit is arranged in the display module and is connected with the output end of the differential operational amplification interface circuit;
the power ground of the camera is connected with the power ground of the display module; wherein
The differential operational amplification interface circuit comprises:
the operational amplifier is connected with the camera;
a filter circuit connected between a power supply and the operational amplifier;
the low-pass filter circuit includes:
the circuit comprises a resistor R10, an inductor L1 and a capacitor C9 which are sequentially connected in series, wherein one end of the resistor R10 is connected with the output end of the operational amplifier;
and one end of the capacitor C8 is connected between the capacitor C9 and the inductor L1, and the other end of the capacitor C8 is grounded.
2. The on-vehicle analog video signal anti-jamming system according to claim 1, wherein the operational amplifier includes:
one end of the resistor R10 is connected with the output end of the operational amplification chip;
one end of the resistor R4 is connected with the inverting input end of the operational amplification chip;
one end of the resistor R5 is connected with the positive phase input end of the operational amplification chip;
one end of the resistor R6 is connected with one end of the resistor R4, and the other end of the resistor R6 is connected with the output end of the operational amplification chip;
the resistor R7 and the resistor R8 are connected in series, one end of the resistor R7 is connected with a power supply end of the operational amplification chip, and the resistor R8 is grounded;
the two ends of the capacitor C1 are respectively connected with the positive phase input end and the negative power end of the operational amplification chip;
and one end of the capacitor C7 is connected with the inverting input end of the operational amplification chip, and the other end of the capacitor C7 is connected with the output end of the operational amplification chip.
3. The on-vehicle analog video signal anti-jamming system according to claim 2, wherein the filter circuit comprises:
the circuit comprises a resistor R9 and a capacitor C5 which are connected in series, wherein one end of the resistor R9 is connected with the power supply, one end of the capacitor C5 is grounded, and a positive power supply end of the operational amplification chip is connected between the resistor R9 and the capacitor C5;
and one end of the capacitor C6 is connected between the capacitor C5 and the resistor R9, and the other end of the capacitor C6 is grounded.
4. The system for resisting vehicle-mounted analog video signals according to claim 2, further comprising:
the camera comprises a resistor R1 and a capacitor C3 which are connected in series, wherein one end of the resistor R1 is connected with a signal negative phase output end of the camera, and one end of the capacitor C3 is connected with the other end of the resistor R4;
the camera comprises a resistor R2 and a capacitor C2 which are connected in series, wherein one end of the resistor R2 is connected with a signal positive phase output end of the camera, and one end of the capacitor C2 is connected with the other end of the resistor R5;
the resistor R3, the one end of resistor R3 is connected the resistor R1 with between the electric capacity C3, the other end of resistor R3 is connected the resistor R2 with between the electric capacity C2.
5. The on-vehicle analog video signal anti-jamming system according to claim 2 or 3, wherein the operational amplifier chip is TI OPA354.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611075564.7A CN106657715B (en) | 2016-11-30 | 2016-11-30 | Vehicle-mounted analog video signal anti-interference system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611075564.7A CN106657715B (en) | 2016-11-30 | 2016-11-30 | Vehicle-mounted analog video signal anti-interference system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN106657715A CN106657715A (en) | 2017-05-10 |
| CN106657715B true CN106657715B (en) | 2023-03-31 |
Family
ID=58813221
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201611075564.7A Active CN106657715B (en) | 2016-11-30 | 2016-11-30 | Vehicle-mounted analog video signal anti-interference system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN106657715B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108259704B (en) * | 2018-03-23 | 2024-04-30 | 深圳市豪恩汽车电子装备股份有限公司 | Video output circuit of vehicle-mounted camera |
| CN109525750B (en) * | 2018-12-03 | 2020-10-16 | 深圳市车联天下信息科技有限公司 | Vehicle-mounted reversing video circuit and control method |
| CN109802748B (en) * | 2019-03-18 | 2023-08-25 | 延锋伟世通电子科技（上海）有限公司 | High-immunity differential camera signal processing circuit |
| CN109743474B (en) * | 2019-03-18 | 2023-04-25 | 延锋伟世通电子科技（上海）有限公司 | High-noise-immunity single-ended camera signal processing circuit |
| CN111770248A (en) * | 2020-06-24 | 2020-10-13 | 广州四为电子科技有限公司 | Analog video signal water ripple suppression circuit and panoramic parking system |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5627898A (en) * | 1993-11-19 | 1997-05-06 | Washino; Kinya | Signal distribution with user-configurable ground-loop control |
| USRE37130E1 (en) * | 1992-05-08 | 2001-04-10 | David Fiori, Jr. | Signal conditioning apparatus |
| CN201821448U (en) * | 2010-09-30 | 2011-05-04 | 中国航天科工集团第三研究院第八三五七研究所 | Anti-interference device for analog video signal |
| CN204290889U (en) * | 2014-12-05 | 2015-04-22 | 杭州海康威视数字技术股份有限公司 | A kind of filtering and amplifying circuit |
| CN106161876A (en) * | 2016-07-29 | 2016-11-23 | 惠州华阳通用电子有限公司 | A kind of circuit suppressing Earth noise to disturb |
| CN206350063U (en) * | 2016-11-30 | 2017-07-21 | 延锋伟世通电子科技（上海）有限公司 | Vehicle-mounted analog video signal jamproof system |
-
2016
- 2016-11-30 CN CN201611075564.7A patent/CN106657715B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| USRE37130E1 (en) * | 1992-05-08 | 2001-04-10 | David Fiori, Jr. | Signal conditioning apparatus |
| US5627898A (en) * | 1993-11-19 | 1997-05-06 | Washino; Kinya | Signal distribution with user-configurable ground-loop control |
| CN201821448U (en) * | 2010-09-30 | 2011-05-04 | 中国航天科工集团第三研究院第八三五七研究所 | Anti-interference device for analog video signal |
| CN204290889U (en) * | 2014-12-05 | 2015-04-22 | 杭州海康威视数字技术股份有限公司 | A kind of filtering and amplifying circuit |
| CN106161876A (en) * | 2016-07-29 | 2016-11-23 | 惠州华阳通用电子有限公司 | A kind of circuit suppressing Earth noise to disturb |
| CN206350063U (en) * | 2016-11-30 | 2017-07-21 | 延锋伟世通电子科技（上海）有限公司 | Vehicle-mounted analog video signal jamproof system |
Non-Patent Citations (1)
| Title |
|---|
| 弱电系统中的地线干扰与接地方法;曹振平;《电子工程师》;20040430(第04期);全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN106657715A (en) | 2017-05-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106657715B (en) | Vehicle-mounted analog video signal anti-interference system | |
| CN206004626U (en) | A kind of anti-interference differential amplifier circuit for vehicle-mounted analog video | |
| WO2015159684A1 (en) | Communication apparatus | |
| JP5903993B2 (en) | Communications system | |
| US10560154B2 (en) | Power line signal coupler | |
| EP1492287A1 (en) | Receiver | |
| JP6047907B2 (en) | Communication apparatus and communication system | |
| CN107134916B (en) | Device and method for preventing electromagnetic information leakage in alternating-current power supply transmission | |
| CN110471490B (en) | Passive crystal oscillator sharing circuit | |
| CN203554278U (en) | A household electrical appliance and an EMI filter circuit thereof | |
| US20140009243A1 (en) | Network signal coupling and emi protection circuit | |
| US20080174387A1 (en) | Filter circuit for reducing emi of differential signal | |
| CN102059991A (en) | CAN (controller area network) bus interface circuit for hybrid power automobile system | |
| CN107021035B (en) | Vehicle-mounted display and vehicle-mounted display system | |
| CN216930177U (en) | Anti-interference circuit for vehicle-mounted display video signal transmission | |
| CN211656211U (en) | On-vehicle CVBS composite video signal keeps apart filter circuit | |
| CN206350063U (en) | Vehicle-mounted analog video signal jamproof system | |
| CN211151929U (en) | High definition multimedia interface HDMI and filter circuit thereof | |
| CN210572692U (en) | Feed-through filter applied to magnetic resonance system and magnetic resonance system | |
| CN208987092U (en) | A kind of vehicle-mounted SDI interface circuit | |
| CN217363098U (en) | Communication isolation circuit | |
| CN107579737B (en) | Anti- phase distortion component | |
| CN216721289U (en) | Motor EMC filter circuit, filter structure, motor and vehicle | |
| JP2016165081A (en) | Noise filter | |
| CN219834106U (en) | Filtering circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |