KR20100102763A - Transmitting circuit of power line communication modem for cctv - Google Patents
Transmitting circuit of power line communication modem for cctv Download PDFInfo
- Publication number
- KR20100102763A KR20100102763A KR1020090020977A KR20090020977A KR20100102763A KR 20100102763 A KR20100102763 A KR 20100102763A KR 1020090020977 A KR1020090020977 A KR 1020090020977A KR 20090020977 A KR20090020977 A KR 20090020977A KR 20100102763 A KR20100102763 A KR 20100102763A
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- South Korea
- Prior art keywords
- power line
- oscillator
- transistor
- oscillation frequency
- oscillation
- Prior art date
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/04—Systems for the transmission of one television signal, i.e. both picture and sound, by a single carrier
- H04N7/045—Systems for the transmission of one television signal, i.e. both picture and sound, by a single carrier the carrier being frequency modulated
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/10—Adaptations for transmission by electrical cable
- H04N7/102—Circuits therefor, e.g. noise reducers, equalisers, amplifiers
-
- 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
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- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Closed-Circuit Television Systems (AREA)
- Studio Devices (AREA)
Abstract
In the power line communication modem of a surveillance camera device, there is provided a transmission circuit of a power line modem for a surveillance camera that can simplify the circuit configuration by simultaneously implementing a modulator and an oscillator for image modulation. A transmission circuit of a power line modem for surveillance cameras includes: a transistor (TR1) for amplifying and outputting a video signal having a first bandwidth provided from a surveillance camera in a transmission circuit of a power line modem of a surveillance camera using a power line communication method; A variable resistor TR2 for adjusting a DC bias voltage applied to the amplifying stage output of the transistor TR1 to a predetermined voltage or more; An oscillator (OSC) having an oscillation frequency having a second bandwidth and directly connected to a terminal voltage applied to an amplifying stage output of the transistor TR1 and modulating and outputting an image signal to an oscillation frequency; And a transformer T1 for converting the video signal output modulated in the oscillation frequency band by the oscillator into an AC (AC) video signal. At this time, the oscillator OSC starts oscillation from the adjusted bias voltage and simultaneously performs image signal modulation and oscillation.
Description
BACKGROUND OF THE
In general, in security systems that are built for the purpose of crime prevention or disaster prevention, or automation systems that want to pursue convenience of life by automatically or remotely controlling indoor electronic devices, surveillance cameras are installed indoors and outdoors to monitor the surroundings in real time. It is used.
Such a surveillance camera has an image capturing function and a transmission function, and photographs and transmits an image of a surrounding, and transmits the image transmitted from the surveillance camera to a predetermined designated display device for monitoring.
1 is a schematic configuration diagram of a surveillance camera device according to the related art.
Referring to FIG. 1, a surveillance camera device according to the related art is a CCD (Charge Coupled Device)
The
In the case of the transmission unit of the surveillance camera according to the prior art, it can be divided into a wired transmission and a wireless transmission according to the transmission method, in general, CCTV cameras, because they are used for a limited purpose in a limited space, wired transmission method is a lot Used. In fact, the radio transmission scheme has many limitations due to radio frequency allocation problems and interference problems. And even in the wired transmission method, a baseband transmission method for transmitting a video signal as it is, a carrier transmission method for modulating and transmitting a video signal, a PCM transmission method for converting an image signal into a PCM, and an optical signal. Various methods such as optical communication transmission methods for converting signals are used, but all of these transmission methods must use coaxial cables or optical cables for signal transmission. Therefore, it is difficult to install and manage such a coaxial cable for transmitting a video signal, and it has a problem in that the cost is added.
As described above, the conventional surveillance cameras installed in indoor and outdoor remote areas require a
On the other hand, recently, a power line communication (PLC) technology has been developed that can transmit voice and text data, video, etc. using only an electrical outlet, that is, a power line, and this power line communication can be installed using an existing optical communication cable. In addition to the low cost, it also has the advantage that it costs little to no communication.
2 is a schematic configuration diagram of a surveillance camera device of a power line communication method according to the related art.
As shown in FIG. 2, the monitoring camera apparatus of the power line communication method according to the related art can supply power and transmit signals only by the
As a first prior art for solving the problem of the surveillance camera according to the prior art, Korean Patent Application No. 2000-32364 (filed date: June 13, 200) is named "camera with a power line communication modem" The invention of is disclosed. According to the first prior art, by embedding a power line communication modem in the CCD camera so that the image signal and control signal of the CCD camera can be transmitted to another system using a power line, data transmission is possible without installing a data transmission cable. Do.
In the case of the power line communication modem embedded in such a CCD camera, the transmission circuit is configured such that an image modulator is necessary. However, the transmission circuit of the power line communication modem according to the related art has a problem in that the circuit structure is complicated as the modulation unit and the oscillation unit are separately configured for image modulation.
The technical problem to be solved by the present invention is to provide a power line communication camera of the surveillance camera device, the power line for the surveillance camera that can simplify the circuit configuration by implementing a modulator and an oscillator for image modulation at the same time. To provide a modem transmission circuit.
As a means for achieving the above-described technical problem, the transmission circuit of the power line modem for surveillance camera according to the present invention, in the transmission circuit of the power line modem of the surveillance camera using the power line communication method, the first bandwidth provided from the surveillance camera. A transistor TR1 for amplifying and outputting a video signal; A variable resistor VR2 for adjusting a DC bias voltage applied to the amplification stage output of the transistor TR1 to a predetermined voltage or more; An oscillator (OSC) having an oscillation frequency having a second bandwidth and directly connected to a terminal voltage applied to an output of the amplifier stage of the transistor TR1 and modulating the image signal to the oscillation frequency and outputting the oscillation frequency; And a transformer T1 for converting the video signal output modulated to the oscillation frequency band by the oscillator into an AC (AC) video signal.
Here, the image signal converted into the alternating current output from the transformer T1 is transmitted to the image display unit through an AC power line.
Here, the oscillator OSC starts oscillation from the adjusted bias voltage, and simultaneously modulates and oscillates the image signal.
The variable resistor VR2 adjusts the DC bias voltage applied to the amplification stage output of the transistor TR1 to be 2.6V or more.
The oscillator OSC has an oscillation frequency having a second bandwidth of 20 MHz, and modulates and outputs an image signal having a first bandwidth in a range of 15.74 kHz to 4 MHz according to the oscillation frequency at 20 MHz. It features.
On the other hand, as another means for achieving the above technical problem, the transmission circuit of the power line modem for surveillance camera according to the present invention is 15.74 provided from the surveillance camera in the power circuit modem transmission circuit of the surveillance camera using the power line communication system. A transistor TR1 for amplifying and outputting an image signal having a bandwidth in the range of kHz to 4MHz; A variable resistor VR2 for adjusting a DC bias voltage applied to the amplification stage output of the transistor TR1 to 2.6 V or more; An oscillation frequency having a 20 MHz bandwidth, directly connected to the terminal voltage applied to the output of the amplifying stage of the transistor TR1, and starting the oscillation from the bias voltage adjusted to 2.6 V or more, An oscillator (OSC) for modulating and outputting at an oscillation frequency; And a transformer (T1) for converting the video signal output modulated in the 20 MHz oscillation frequency band by the oscillator into an AC (AC) video signal, wherein the oscillator oscillates from the bias voltage adjusted to 2.6 V or more. Start and simultaneously perform image signal modulation and oscillation.
According to the present invention, in a power line communication modem of a surveillance camera device, a circuit configuration can be simplified by simultaneously implementing a modulator and an oscillator for image modulation. Accordingly, by integrating various cables necessary for the installation of a CCTV camera or web camera for CCTV into a power line, by simply configuring an image modulation circuit, manufacturing and installation costs are reduced, and maintenance and repair are easy.
DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.
First, referring to FIGS. 3 and 4, the principle of power line communication (PLC) and a method of combining a power line and an image signal will be briefly described.
3 is a view for explaining the principle of power line communication (PLC), Figure 4 is a view for explaining a method of combining the power line and the image signal.
Referring to FIG. 3, power line communication (PLC) uses a frequency-division multiplexing (FDM) principle in which a power line is used as a communication line to multiplex and transmit power and communication signals simultaneously. Multiplexing a communication signal which is a high frequency signal in the range of several tens of Hz to several tens of MHz.
For example, a communication signal transmitted from a PLC modem on the sending side is multiplexed with a 60Hz AC power supply via a high pass filter, transmitted through a power line, and then separated from the 60Hz AC power supply on the receiving PLC modem. The image display unit may be output through a monitor.
In addition, if the communication method of securing the communication reliability of the power line and does not affect the quality of the power source is applied, by using the power outlet as a communication terminal, it is possible to use the communication network anywhere and conveniently.
Referring to FIG. 4, the combination of the power line and the image signal mainly uses capacitive coupling and may be used together with an inductor. If the modem is directly connected to the power line to transmit and receive data through the current
In addition, for the coupling of the power line and the video signal, it is desirable to have a high impedance at the time of reception with respect to the communication frequency or to have a low frequency at the time of transmission with respect to the transmission frequency.
On the other hand, according to an embodiment of the present invention, in the power line communication modem of a surveillance camera device, there is provided a transmission circuit of a power line modem for a surveillance camera that can implement a modulator and an oscillator for image modulation at the same time.
5 is a schematic configuration diagram of a surveillance camera device having a power line modem according to an embodiment of the present invention.
Referring to FIG. 5, a surveillance camera device having a power line modem according to an embodiment of the present invention includes a
In the embodiment of the present invention, the
6 is a diagram illustrating a transmission circuit of a power line modem for surveillance camera according to an embodiment of the present invention.
Referring to FIG. 6, the transmitting
The
That is, when the output of the image signal s1 of the
Accordingly, the 20
Subsequently, an output is applied to the first transformer T1 through the first capacitor C1 so that an image signal of
Therefore, the image signal converted into alternating current output from the first transformer T1 is transmitted to the
As a result, the oscillation and modulation are simultaneously performed by the
7 is a diagram illustrating a receiving circuit of a power line modem for surveillance camera according to an embodiment of the present invention.
Referring to FIG. 7, the receiving circuit of the power line modem for surveillance camera according to the embodiment of the present invention may be configured in the same manner as a general receiving unit, and the video signal of the
At the same time, the low frequency signal rectified by the rectifying diode D1 and filtered by the sixth capacitor C6, that is, the image signal, is amplified by the
As a result, the transmission circuit of the power line modem for surveillance cameras according to the embodiment of the present invention can implement a conventional complex modulation and oscillation at the same time by directly connecting the terminal voltage applied to the output of the amplifying stage of the CCTV camera image signal output to the oscillator. .
In addition, although the transmission circuit of the power line modem according to the embodiment of the present invention has been described for a surveillance camera, it is obvious to those skilled in the art that the present invention can be applied to the power line modem for other purposes without being limited thereto.
The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.
The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present invention. Should be.
1 is a schematic configuration diagram of a surveillance camera device according to the related art.
2 is a schematic configuration diagram of a surveillance camera device of a power line communication method according to the related art.
3 is a diagram for explaining the principle of power line communication (PLC).
4 is a view for explaining a method of combining a power line and an image signal.
5 is a schematic configuration diagram of a surveillance camera device having a power line modem according to an embodiment of the present invention.
6 is a diagram illustrating a transmission circuit of a power line modem for surveillance camera according to an embodiment of the present invention.
7 is a diagram showing a receiving circuit of a power line modem for surveillance camera according to an embodiment of the present invention.
<Brief Description of Reference Numbers>
100: surveillance camera (CCD) 110: power line modem
111: oscillator 200: power line
300: video display unit 310: power line modem
311, 312: video amplifier
VR1: first variable resistor VR2: second variable resistor
TR1: first transistor T1: first transformer
T2: second transformer VC1: variable capacitor
IFT1: Intermediate Frequency Transformer
C1 to C7: capacitors R1 and R2: resistors
D1: rectifier diode
Claims (6)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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KR1020090020977A KR20100102763A (en) | 2009-03-12 | 2009-03-12 | Transmitting circuit of power line communication modem for cctv |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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KR1020090020977A KR20100102763A (en) | 2009-03-12 | 2009-03-12 | Transmitting circuit of power line communication modem for cctv |
Publications (1)
Publication Number | Publication Date |
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KR20100102763A true KR20100102763A (en) | 2010-09-27 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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KR1020090020977A KR20100102763A (en) | 2009-03-12 | 2009-03-12 | Transmitting circuit of power line communication modem for cctv |
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KR (1) | KR20100102763A (en) |
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2009
- 2009-03-12 KR KR1020090020977A patent/KR20100102763A/en not_active Application Discontinuation
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