CN111175568A - Structure for realizing POC detection and power supply protection - Google Patents
Structure for realizing POC detection and power supply protection Download PDFInfo
- Publication number
- CN111175568A CN111175568A CN202010034360.9A CN202010034360A CN111175568A CN 111175568 A CN111175568 A CN 111175568A CN 202010034360 A CN202010034360 A CN 202010034360A CN 111175568 A CN111175568 A CN 111175568A
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- poc
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- recorder
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/20—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for electronic equipment
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- Engineering & Computer Science (AREA)
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- Protection Of Static Devices (AREA)
Abstract
The invention discloses a structure for realizing POC detection and power supply protection, which comprises: adding a ground detection resistor on a power supply path at the end of the POC camera, wherein the detection resistor is used for enabling the POC recorder at the opposite end to identify the POC camera or the non-POC camera; specifically, when a coaxial cable is connected with a POC (point of sale) recorder end, the POC recorder end and the detection resistor form resistance voltage division, so that the POC recorder end can correctly detect the POC camera; and a POC camera detection circuit, an overcurrent and short-circuit detection circuit, an MCU control shunt switch, a relay physical switch and a power supply control circuit are arranged at the end of the POC recorder. The structure can accurately detect various states of the front end connected with the POC recorder and the POC recorder, so that the recorder and the player supporting the POC function can safely use various cameras.
Description
Technical Field
The invention relates to the technical field of video transmission, in particular to a structure for realizing POC detection and power supply protection.
Background
In a POC (Power over Coax, coaxial cable powered) recording and broadcasting system, a camera supporting a POC function is generally used in cooperation with a recorder supporting the POC function, because the POC system usually uses a high-voltage direct current greater than 12V DC, and a video input port of a common camera is usually a chip scheme of 3.3V DC or 1.8V DC, if the POC recorder uses the common camera, the problem of burning the camera is often caused without a safe POC detection and Power supply protection structure, resulting in damage to equipment.
In addition, if the coaxial cable for video transmission is used in engineering, the coaxial cable is generally manufactured by field wiring, and if the wire is not manufactured in a standard manner or the BNC interface of the wire is loosened after being pulled out and inserted for many times, the wire is short-circuited, and a camera or a recorder is burnt; if finished wires are purchased, the cost is high, the POC recording and broadcasting system cannot adapt to the field environment, the installation cost of the POC recording and broadcasting system is increased due to the problems, professional personnel are required to manufacture the wires, the wires need to be checked and maintained regularly, and the maintenance cost and the labor cost are increased.
Disclosure of Invention
The invention aims to provide a structure for realizing POC detection and power supply protection, which can accurately detect various states of the front end connected with a POC recorder, ensures that the recorder supporting the POC function can safely use various cameras, and has the functions of real-time current detection, short-circuit detection and protection.
The purpose of the invention is realized by the following technical scheme:
an architecture for implementing POC detection and power supply protection, comprising:
adding a ground detection resistor on a power supply path at the end of the POC camera, wherein the detection resistor is used for enabling the POC recorder at the opposite end to identify the POC camera or the non-POC camera; specifically, when a coaxial cable is connected with a POC (point of sale) recorder end, the POC recorder end and the detection resistor form resistance voltage division, so that the POC recorder end can correctly detect the POC camera; if the camera is not a POC camera or a camera without the detection resistor, the camera is regarded as an open circuit, and a loop is not formed between the camera and the POC recorder end, so that the POC camera or the non-POC camera is identified;
be provided with POC camera detection circuitry, overflow and short-circuit detection circuitry, MCU control shunt switch, relay physical switch and power supply control circuit at POC recorded broadcast machine end, wherein:
the POC camera detection circuit is used for detecting the access state of the front-end POC camera before power-on, and comprises the POC camera, a common camera, a short circuit state and an open circuit state;
the over-current and short-circuit detection circuit is a differential detection amplifying circuit consisting of a sampling resistor and a triode amplifying resistor, when a POC circuit starts to supply power, current flows through the sampling resistor, a tiny voltage difference can be generated at two ends of the sampling resistor, the voltage difference is increased along with the increase of the current, and the voltage difference is amplified by the triode amplifying resistor and converted into a voltage component to be transmitted to an ADC (analog to digital converter) of the MCU for detection, so that the real-time detection of the current is realized;
the MCU control shunt switch is used for realizing multi-path separate control when a plurality of cameras are connected to the POC recorder end;
the relay physical switch is a main switch for supplying power to the POC recorder terminal, is used for controlling a power supply and isolating surge at the moment of power up and power down, and plays a role in protection;
the power supply control circuit adopts the MCU and the main processor to control the POC relay through the AND gate, and particularly, when the MCU detects an abnormal condition, the system is firstly powered off, then the main processor is informed of the system abnormality through a communication port with the main processor, and then the system gives an alarm.
The technical scheme provided by the invention can show that the structure can accurately detect various states of the front end connected with the POC recorder and the POC recorder, so that the recorder and the broadcasting machine supporting the POC function can safely use various cameras, and have the functions of real-time current detection, short circuit detection and protection.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of implementing POC detection and power supply protection according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a POC camera according to an embodiment of the present invention;
fig. 3 is a schematic circuit diagram of a POC recorder according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
The following will describe the embodiment of the present invention in further detail with reference to the accompanying drawings, and as shown in fig. 1, a schematic structural diagram for implementing POC detection and power supply protection provided by the embodiment of the present invention is shown, where the structure includes:
adding a ground detection resistor on a power supply path at the end of the POC camera, wherein the detection resistor is used for enabling the POC recorder at the opposite end to identify the POC camera or the non-POC camera; specifically, when a coaxial cable is connected with a POC (point of sale) recorder end, the POC recorder end and the detection resistor form resistance voltage division, so that the POC recorder end can correctly detect the POC camera; if the camera is not a POC camera or a camera without the detection resistor, the camera is regarded as an open circuit, and a loop can not be formed with the POC recorder end, so that the identification of the POC camera or the non-POC camera is realized, and therefore, under the condition that the non-POC camera is used, the POC recorder is only a common recorder and the POC function can not be started;
in a specific implementation, the added resistance value of the detection resistor is between 10k and 20 k.
As shown in fig. 2, which is a schematic structural diagram of the POC camera according to the embodiment of the present invention, except for the ground detection resistor added in the power path, since the camera is a power receiving end, that is, a load end, and when the POC system is in normal operation, a high voltage dc power supply is combined in a video transmitted through a coaxial cable, a dc blocking capacitor is added at a position where the SDI Transmitter chip is connected to the POC camera, and a dc blocking capacitor is also added before the modem circuit; by utilizing the blocking characteristic of the added blocking capacitor, the composite high-voltage direct-current power supply in the video transmission through the coaxial cable is prevented from burning circuit elements. In a specific implementation, the blocking capacitance value is less than 1uF, preferably 0.1uF, and if the capacitance value is too large, a high-voltage pulse may be generated at the load end at the moment of power-on, which may damage the element; too small a capacitance value may affect signal transmission. The power load circuit needs a direct current power supply, so that a direct current blocking capacitor does not need to be added.
Fig. 3 is a schematic diagram of a circuit structure of a POC recorder according to an embodiment of the present invention, in which a POC camera detection circuit, an overcurrent and short-circuit detection circuit, an MCU controlled shunt switch, a physical relay switch, and a power supply control circuit are disposed at the POC recorder, wherein:
the POC camera detection circuit is used for detecting the access state of the front-end POC camera before power-on, and comprises the POC camera, a common camera, a short circuit state and an open circuit state; in a specific implementation, referring to fig. 3: if a POC video camera is connected to the POC video recorder end, 3.3V DC voltage passes through a resistor R1 and a diode D1, a ground detection resistor is arranged at the other end of the coaxial cable for voltage division, the voltage division resistor is connected to an ADC port of the MCU through an ADC2 signal line for detection, for example, if R1 and a detection resistance value are both 10k, the voltage drop on D1 is not calculated, and the voltage value detected by the MCU is about 1.6V; if the connected POC camera is not the POC camera or the POC camera without the detection resistor, a voltage division loop cannot be formed, the voltage value detected by the MCU is 3.3V, and the phase difference is obvious; meanwhile, under the condition that the camera or the video line is short-circuited, the voltage value detected by the MCU is 0V, so that the front end state of the POC recorder-player end can be judged by distinguishing the voltage values.
The over-current and short circuit detection circuit is a differential detection amplifying circuit composed of a sampling resistor and a triode amplifying resistor, and refer to fig. 3: after the POC circuit starts to supply power, current flows through the sampling resistor R2, and because V is R I, a tiny voltage difference is generated at two ends of the sampling resistor R2, the voltage difference is increased along with the increase of the current, and the voltage difference is amplified by the triode amplifying resistor and converted into a voltage component to be transmitted to the ADC of the MCU for detection, so that the real-time detection of the current is realized; in the specific implementation, the POC power supply voltage is assumed to be 24V DC, and the power of the camera is about 10W, so that the sampling resistor needs to be a high-precision resistor with a small resistance value and a large package, and if the use environment is complex, the alloy material sampling resistor is recommended to be selected, and the first resistance value is about 0.25 Ω. In addition, the program of the MCU can also control the POC power supply to be cut off when the normal working current of the camera is exceeded, so that the real-time protection of the camera is achieved, if the short circuit occurs, the power supply can be cut off rapidly, the safety of a circuit is protected, and an alarm signal can be sent out.
The MCU control shunt switch is used for realizing multi-path separate control when a plurality of cameras are connected to the POC recorder end;
the relay physical switch is a main switch for supplying power to the POC recorder terminal, is used for controlling a power supply and isolating surge at the moment of power up and power down, and plays a role in protection; specifically, if a plurality of cameras are simultaneously powered, the current is larger, so that the relay control can provide larger current, and the problem of electric leakage caused by aging of devices can be avoided because the relay is a physical switch;
the power supply control circuit adopts the MCU and the main processor to control the POC relay through the AND gate, and particularly, when the MCU detects an abnormal condition, the system is firstly powered off, then the main processor is informed of the abnormal condition of the system through a communication port with the main processor, and then the system gives an alarm, so that the power supply safety of the system is ensured, and the processing time under the abnormal current condition is shortened.
It is noted that those skilled in the art will recognize that embodiments of the present invention are not described in detail herein.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (3)
1. A structure for realizing POC detection and power supply protection, comprising:
adding a ground detection resistor on a power supply path at the end of the POC camera, wherein the detection resistor is used for enabling the POC recorder at the opposite end to identify the POC camera or the non-POC camera; specifically, when a coaxial cable is connected with a POC (point of sale) recorder end, the POC recorder end and the detection resistor form resistance voltage division, so that the POC recorder end can correctly detect the POC camera; if the camera is not a POC camera or a camera without the detection resistor, the camera is regarded as an open circuit, and a loop is not formed between the camera and the POC recorder end, so that the POC camera or the non-POC camera is identified;
be provided with POC camera detection circuitry, overflow and short-circuit detection circuitry, MCU control shunt switch, relay physical switch and power supply control circuit at POC recorded broadcast machine end, wherein:
the POC camera detection circuit is used for detecting the access state of the front-end POC camera before power-on, and comprises the POC camera, a common camera, a short circuit state and an open circuit state;
the over-current and short-circuit detection circuit is a differential detection amplifying circuit consisting of a sampling resistor and a triode amplifying resistor, when a POC circuit starts to supply power, current flows through the sampling resistor, a tiny voltage difference can be generated at two ends of the sampling resistor, the voltage difference is increased along with the increase of the current, and the voltage difference is amplified by the triode amplifying resistor and converted into a voltage component to be transmitted to an ADC (analog to digital converter) of the MCU for detection, so that the real-time detection of the current is realized;
the MCU control shunt switch is used for realizing multi-path separate control when a plurality of cameras are connected to the POC recorder end;
the relay physical switch is a main switch for supplying power to the POC recorder terminal, is used for controlling a power supply and isolating surge at the moment of power up and power down, and plays a role in protection;
the power supply control circuit adopts the MCU and the main processor to control the POC relay through the AND gate, and particularly, when the MCU detects an abnormal condition, the system is firstly powered off, then the main processor is informed of the system abnormality through a communication port with the main processor, and then the system gives an alarm.
2. The structure for realizing POC detection and power supply protection according to claim 1, wherein the added detection resistor has a resistance value between 10k and 20 k.
3. The architecture for enabling POC detection and power supply protection according to claim 1,
a DC blocking capacitor is added at the position where an SDI Transmitter chip is connected to the end of the POC camera, and a DC blocking capacitor is also added in front of a modulation-demodulation circuit, so that the circuit elements are prevented from being burnt by a composite high-voltage DC power supply in a video transmitted by a coaxial cable by utilizing the DC blocking characteristic of the added DC blocking capacitor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010034360.9A CN111175568A (en) | 2020-01-13 | 2020-01-13 | Structure for realizing POC detection and power supply protection |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010034360.9A CN111175568A (en) | 2020-01-13 | 2020-01-13 | Structure for realizing POC detection and power supply protection |
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| CN111175568A true CN111175568A (en) | 2020-05-19 |
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| CN202010034360.9A Pending CN111175568A (en) | 2020-01-13 | 2020-01-13 | Structure for realizing POC detection and power supply protection |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113176492A (en) * | 2021-03-10 | 2021-07-27 | 深圳市豪恩汽车电子装备股份有限公司 | Method for measuring scattering parameters of POC circuit |
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| CN208538008U (en) * | 2018-07-11 | 2019-02-22 | 深圳开立生物医疗科技股份有限公司 | A kind of linear voltage-stabilizing circuit with overcurrent protection |
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- 2020-01-13 CN CN202010034360.9A patent/CN111175568A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102426285A (en) * | 2011-09-14 | 2012-04-25 | 深圳航天科技创新研究院 | Current sensor used for bidirectional current sampling |
| CN104702879A (en) * | 2015-02-09 | 2015-06-10 | 杭州海康威视数字技术股份有限公司 | Rear end and front end processing circuits and coaxial power supply circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113176492A (en) * | 2021-03-10 | 2021-07-27 | 深圳市豪恩汽车电子装备股份有限公司 | Method for measuring scattering parameters of POC circuit |
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Application publication date: 20200519 |