KR101827796B1 - Network modem apparatus having impedence matching function - Google Patents

Abstract

The present invention relates to a network modem apparatus, and more particularly, to a network modem apparatus comprising a data conversion unit for converting digital data into an analog signal and outputting the analog signal, an impedance matching unit for matching the analog signal output from the data conversion unit with the characteristic impedance of the coaxial cable, A voltage conversion unit that receives a voltage as an input and converts the voltage into a necessary number of required voltages, and an external power supply unit that supplies a predetermined DC voltage to an external terminal device via an external LAN. The conventional coaxial cable can be used as it is, and the signal can be received without reducing the signal level through impedance matching.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a network modem apparatus having an impedance matching function,

The present invention relates to a network modem apparatus, and more particularly, to a network modem apparatus having an impedance matching function for impedance matching when the characteristic impedance of a coaxial cable is different or a plurality of coaxial cables can be connected through a signal distributor.

Conventionally, analog cameras have been widely used, and video images taken by analog cameras have been transferred to the management apparatus through coaxial cables. However, in recent years, analog cameras have gradually been replaced by digital cameras in response to the demands of users who demand high image quality.

When replacing an analog camera with a digital camera, instead of just replacing the analog camera, you need to install a new cable suitable for digital transmission instead of the analogue coaxial cable that was already installed. In this case, upgrading is not easy due to the increase in new installation and construction costs.

On the other hand, Power Line Communication (PLC) is used to transmit and receive data. Power line communication refers to a communication system that transmits and receives data through a power line wired for power supply to a home or office. That is, the power line communication can be realized by modulating the data information into the high-frequency signal on the power line and transmitting the high-frequency signal by separating and receiving the high-frequency signal using the filter having the cutoff frequency of 50 Hz or 60 Hz.

A method of transmitting an analog signal and a digital signal using such power line communication is disclosed in Korean Patent Laid-Open Publication No. 2013-0042086. However, such a power line communication scheme is not suitable for a coaxial cable, and another cost increase is required for applying a power line communication scheme.

In order to solve the above-mentioned problems, the present inventors have invented a network modem device which can use existing coaxial cable as it is and replace it with a digital camera instead of an analog camera, Respectively.

However, if the coaxial cables have different characteristic impedances, or if multiple coaxial cables are connected through a signal splitter to cause impedance mismatch, no other network modem device could receive the signal.

Patent Document 1: Korean Patent Publication No. 2013-0042086

In order to solve the problems described above, the present invention provides a network modem apparatus having an impedance matching function for impedance matching when the characteristic impedance of the coaxial cable is different or when a plurality of coaxial cables can be connected through a signal distributor The purpose.

In order to achieve the above-mentioned object, a network modem apparatus according to an embodiment of the present invention includes a data conversion unit for converting digital data into an analog signal and outputting the analog signal, an analog signal output from the data conversion unit, An impedance matching unit for matching a predetermined direct current voltage with an impedance, a voltage conversion unit for receiving a predetermined direct current voltage as an input and converting the direct current voltage into a necessary number of necessary voltages, and an external power source for supplying the predetermined direct current voltage to an external terminal device Supply unit.

The data conversion unit may receive Ethernet packet data from the external terminal device as digital data and output the OFDM signal as an analog signal.

The data conversion unit may include a data conversion chip for converting the Ethernet packet data into an OFDM signal for a coaxial cable, and an analog front end chip for amplifying and outputting an OFDM signal for a coaxial cable output from the data conversion chip.

The data conversion unit may control the gain of the analog front end chip to adjust the output intensity of the OFDM signal.

The impedance matching unit may include a transformer having one end connected to a transmission filter or a receiving filter of the data conversion chip and the other end connected to a coaxial connector and at least one impedance providing unit connectable to the other end of the transformer.

The impedance matching unit may further include a switch for connecting the at least one impedance providing unit to the transformer in parallel.

The external power supply unit may include a terminal power source detection unit for detecting whether commercial power is being supplied to the external terminal device.

Wherein the external power supply unit comprises: a switching unit for supplying the predetermined DC voltage to the external terminal device; a switching driver for turning on or off the switching unit; And a microcomputer for outputting a turn-on signal to the switching driver when it is determined that commercial power is not supplied to the terminal device.

According to the above-described configuration, the present invention can use a conventional coaxial cable as it is, and can receive a signal without reducing the signal level through impedance matching even if the digital camera is replaced with a digital camera instead of an analog camera.

In addition, the present invention can adjust the output intensity of an analog signal, thereby increasing the coaxial cable length between network modem devices.

In addition, the present invention can be installed in a region where the commercial power is not supplied, so that communication can be performed.

1 is a schematic diagram illustrating a network modem system according to an embodiment of the present invention.
2 is a schematic diagram of a network modem system according to another embodiment of the present invention.
3 is a block diagram of the network modem apparatus shown in FIG.
Fig. 4 is a diagram showing the impedance matching unit shown in Fig. 3 in more detail.
5 is a circuit diagram of the external power supply unit shown in FIG.
6 is a diagram showing a timing signal for detecting the power level of the external terminal device.

Hereinafter, preferred embodiments of a network modem apparatus having an impedance matching function according to the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the technical scope of the present invention. Will be.

1 is a schematic diagram illustrating a network modem system according to an embodiment of the present invention.

1, the network modem system includes an IP camera device 110, a first network modem device 120, a second network modem device 130, a DC voltage generating device 140, and a computer or NVR (DVR And a terminal device 150. FIG. The first network modem device 120 and the second network modem device 130 are connected to a coaxial cable 170 (a first network modem device) And the second network modem device 130 and the computer 150 are connected to the LAN 160 again.

The IP camera device 110 includes a camera module, an image compression chip, a CPU, and a network transmission chip, which can be used by being connected to a wired / wireless Internet. The analog signal received from the camera module is converted from the image compression chip to digital, compressed, and transmitted to the first network modem device 120 through the network transmission chip. In the present invention, Ethernet packet data is described as digital data output from the IP camera apparatus 110, for example.

The first network modem apparatus 120 and the second network modem apparatus 130 have the same configuration and the first network modem apparatus 120 receives the digital data transmitted from the IP camera apparatus 110 and outputs the same to the coaxial cable 170) and outputs the analog signal. The analog signal transmitted from the first network modem device 120 is received at the second network modem device 130 via the coaxial cable 170. The second network modem device 130 converts the received analog signal into digital data and outputs the digital data.

The DC voltage generating device 140 receives a commercial power source and generates a predetermined DC voltage, for example, a DC voltage of 48V to 56V, and supplies the DC voltage to the second network modem device 130. The second network modem device 130 generates necessary internal voltages using the supplied 48V to 56V direct current voltage. The second network modem device 130 also supplies 48V to 56V DC voltage to the first network modem device 120 via the coaxial cable 170. [ The first network modem device 120 also generates necessary internal voltages using the 48V to 56V DC voltage supplied from the second network modem device 130 and also supplies the 48V to 56V DC voltage to the IP camera device 110 Can supply.

The computer 150 receives the digital data transmitted from the second network modem device 130 via the LAN 160 and stores the received data in the memory.

The coaxial cable 170 connects the first network modem device 120 to the second network modem device 130. In case of the coaxial cable 170 connecting the first network modem apparatus 120 and the second network modem apparatus 130, the characteristic impedance is not constant to 50 ?, 75 ?, or 100 ?. Output impedance of the first network modem apparatus 120 and the second network modem apparatus 130 is designed to be 50 OMEGA. If the characteristic impedance of the coaxial cable 170 already installed is 100 OMEGA, then distortion of the signal is seriously caused by impedance mismatch .

2 is a schematic diagram of a network modem system according to another embodiment of the present invention.

As shown in FIG. 2, the network modem system includes a first IP camera apparatus 110-1, a first network modem apparatus 120-1, a second IP camera apparatus 110-2, A second network modem device 120-2, a third network modem device 130, a distributor 210, a DC voltage generating device 140 and a computer 150. [ The first IP camera apparatus 110-1 and the first network modem apparatus 120-1 and the second IP camera apparatus 110-2 and the second network modem apparatus 120-2 are connected to a LAN The first network modem apparatus 120-1 and the second network modem apparatus 120-2 and the third network modem apparatus 130 are connected to each other via a distributor 210 via a coaxial cable 170, And the second network modem device 130 and the computer 150 are connected to the LAN 160 again.

2, the input / output impedances of the first network modem device 120-1, the second network modem device 120-2, and the third network modem device 130 are designed to be 50?, And the characteristic impedance of the coaxial cable is set to Even if they are designed to have a resistance of 50 ?, since they are connected to each other through the distributor 210, signal distortion occurs due to impedance mismatch.

In FIG. 2, although the first network modem apparatus 120-1 and the second network modem apparatus 120-2 are connected in parallel through the distributor 210, more network modem apparatuses can be connected in parallel. In this case, the distortion of the signal becomes worse.

3 is a block diagram of the network modem apparatus shown in FIG.

3, the network modem apparatus includes an external connection unit 310, a data conversion unit 320, an impedance matching unit 330, a voltage conversion unit 340, and an external power supply unit 350. A unit is a term introduced to help understand the configuration, not the term introduced to physically distinguish the configuration.

As shown in FIG. 1, the external connection unit 310 includes an RJ-45 connector 312 for connecting the IP camera apparatus 110, which is an external terminal apparatus, with a LAN line 160 and another network modem apparatus, for example, And a coaxial connector 314 for connecting via the coaxial cable 170 to the network modem device 130.

The data conversion unit 320 includes an Ethernet PHY chip 321, a data conversion chip 322, a flash memory 323, a DRAM 324, and the like in order to convert digital data into an analog signal and also convert an analog signal into digital data. A security button 325, an analog front end chip 326, a transmit filter 327, and a receive filter.

The Ethernet PHY chip 321 receives the digital data input from the RJ-45 connector 312, that is, the Ethernet packet data, and provides it to the data conversion chip 322.

The data conversion chip 322 converts the Ethernet packet data input from the Ethernet PHY chip 321 into an Orthogonal Frequency Division Multiplexing (OFDM) signal for a coaxial cable that multiplexes the Ethernet packet data with a plurality of orthogonal narrow band carriers.

The data conversion chip 322 internally incorporates an Ethernet-based MAC / PHY and can support a PHY speed of up to 200 Mbps and meets the home plug AV standard. Data conversion chip 322 may also support Internet Group Management Protocol (IGMP) to support multicast sessions and QoS (Quality of Service) functions for various types of quality. The data conversion chip 322 also internally includes a DAC and an ADC.

The flash memory 323 stores not only the firmware associated with the data communication but also values that can be used to set the output intensity in the analog signal transmission.

The DRAM 324 temporarily stores the Ethernet packet data provided from the Ethernet PHY chip 321 during the conversion from the data conversion chip 322 to the OFDM signal for the coaxial cable.

The security button 325 is a button that enables security settings to allow only network modem equipment having the same password to a password, for example 1234567, to communicate the coaxial cable 170 analog signal.

The analog front end chip 326 amplifies the OFDM signal for the coaxial cable output from the data conversion chip 322 and outputs it to the transmission filter 327 or the OFDM signal for the coaxial cable provided by the reception filter 328, And outputs it to the chip 322. On the other hand, the analog front-end chip 326 can control the gain and adjust the output intensity of the OFDM signal,

The transmission filter 327 is a filter for transmitting the amplified OFDM signal from the analog front end chip 326 to the impedance matching unit 330 and for removing noise. The receive filter 328 is a filter for transmitting the OFDM signal provided from the impedance matching unit 330 to the analog front end chip 326 and also for removing noise.

The impedance matching unit 330 enables impedance matching with the external coaxial cable 170 and also transmits the OFDM signal provided through the transmission filter 327 to the coaxial connector 314 and the external coaxial cable 170, To an OFDM signal provided to the coaxial connector 314 via the receive filter 328. [

The voltage converting unit 340 is supplied with a voltage of 48V to 56V from the DC voltage generating device 140 shown in Fig. 1 or through the coaxial cable 170. Fig. The voltage conversion unit 340 converts the voltage of 48V to 56V to provide the 12V voltage to be supplied to the analog front end chip 326 and the 1.26V voltage to be supplied to the data conversion chip 322, 3.3V voltage is obtained.

In the case of the voltage conversion unit 340, since a predetermined DC voltage, for example, a rated voltage to which 48 V to 56 V is input, or a coaxial cable 170 becomes long, a voltage drop is much generated. Do.

The external power supply unit 350 is a unit for supplying power to the LAN 160. When the commercial power is not supplied to the external terminal device such as the IP camera device 110, It is a supply unit. The external power supply unit 350 can detect the required power of the external terminal device and supply either one of two power levels, for example, 15W and 30W.

Fig. 4 is a diagram showing the impedance matching unit shown in Fig. 3 in more detail.

4, the impedance matching unit 330 includes a transformer 332, a first impedance providing unit 334, a second impedance supplying unit 336, and a switch 338.

The transformer 332 electrically isolates the transmit filter 327 or the receive filter 328 from the external coaxial cable 170 and also enables basic impedance matching.

It is preferable that the first impedance providing portion 334 and the second impedance providing portion 336 are connected to the transformer 332 in parallel so as to prevent the signal from being cut off when the switch 338 is switched.

In FIG. 4, the resistor R31, the inductor L1 and the resistor R32 are shown in the first impedance provider 334, the resistor R33, the inductor L3 and the resistor R33 are shown in the second impedance provider 336, The connection may vary depending on the impedance match.

The first impedance supplier 334 may be configured to reduce the overall impedance when connected to the transformer 332 via the switch 338 and the second impedance supplier 336 may be configured to reduce the total impedance through the switch 338, (332), the total impedance may be increased.

In FIG. 4, for example, only two impedance providing units are illustrated, but a plurality of impedance providing units may be provided for impedance matching.

FIG. 5 is a circuit diagram of the external power supply unit shown in FIG. 3, and FIG. 6 is a diagram showing timing signals for detecting the power level of the external terminal device.

5, the external power supply unit 350 includes a terminal power detection unit 510, a switching unit 520, a switching driving unit 530, a terminal power level detection unit 540, and a microcomputer unit 550 do.

The terminal power detection unit 510 detects whether the commercial power is supplied to the IP camera apparatus 110. [ To this end, the terminal power detection unit 510 includes a resistor R1 connected to the Input_PD terminal of the microcomputer 550, a resistor R2 connected to the 3.3V voltage, and a diode D1 connected to the node of the resistor R1 and the resistor R2 and the external terminal Power + . Since the terminal power detection unit is connected to the external terminal Power + with a resistance of 27 K? Of the IP camera apparatus 110, it is possible to detect whether the commercial power is supplied to the IP camera apparatus 110

The switching unit 520 includes a switching device Q1 connected to the 48V to 56V voltage and a capacitor C1 connected to the drain terminal and the source terminal of the switching device Q1 to supply a predetermined DC voltage to the IP camera device 110. [

The switching driver 530 includes a resistor R3 connected to the DRV terminal of the microcomputer unit 550 for turning on or off the switching unit 520, a capacitor C2, a comparator OP1, A resistor R6 connected to the output terminal of the comparator OP1, a resistor R8 connected to the switching transistor TR1 and a voltage between 48V and 56V, and a resistor R8 connected to the collector terminal of the switching transistor TR1 to output the output of the switching transistor TR1 to the switching element Q1 And a resistor R9 provided to the base of the resistor R9.

The terminal power level detector 540 detects a power level required in the IP camera apparatus 110 by using a Zener diode ZD1 connected to the external terminal Power + and the external terminal Power-, a resistor R10 and a resistor R11 connected to the external terminal Power- A resistor R12 connected to the 3.3V voltage, a comparator OP2, a capacitor C3 connected to the output terminal of the comparator OP2, a resistor R13 and a resistor R15, and a resistor R14 connected between the resistor R13 and the ground.

The terminal power level detector 540 detects a power level required for the IP camera apparatus 110 using the time difference of the timing signal input from the IP camera apparatus 110. A timing signal for detecting the power level of the IP camera apparatus 110 is shown in Fig. In FIG. 4, the first signal of the two signals in the middle region indicates Class 1 of the communication standard, and the second signal may indicate Class 2. Where Class 1 or Class 2 refers to the power level, for example the first power level may be 15W and the second power may be 30W.

The microcomputer unit 550 outputs a turn-on signal to the switching driver 530 when it is determined that the commercial power is not supplied to the IP camera apparatus 110 based on the detection voltage detected by the terminal power detector 510.

The microcomputer unit 550 also supplies a continuous turn-on signal to the switching driver 530 if the power level detected by the terminal power level detector 540 is a first power level, It is possible to supply a turn-on signal having a predetermined duty ratio.

Hereinafter, the operation of the network modem apparatus will be briefly described with reference to FIGS. 1 to 6. FIG.

When the network modem system is installed as shown in FIG. 1, the second network modem device 130 is supplied with the 48V to 56V voltage from the DC voltage generator 140.

The 48V to 56V voltage supplied to the second network modem device 130 is supplied to the first network modem device 120 via the coaxial cable 170. And the voltage conversion unit 340 of the second network modem device 130 converts the 48V to 56V voltage to the voltages required for the internal configuration. As a result, the second network modem apparatus 130 is ready for communication.

The voltage conversion unit 340 of the first network modem device 120 also converts the 48V to 56V voltage supplied through the coaxial cable 170 to the voltages required for the internal configuration. As a result, the first network modem apparatus 120 is also ready for communication.

The terminal power detection unit 510 in the external power supply unit 350 of the first network modem apparatus 120 detects whether the commercial power is supplied to the IP camera apparatus 110 and operates, Off signal to the switching driver 530 when it is determined that the commercial power is not supplied to the IP camera apparatus 110 by the detection voltage detected by the terminal power detector 510. [ The switching unit 520 is turned on and a voltage of 48V to 56V is supplied to the IP camera apparatus 110 through the LAN 160. [

Then, the terminal power level detector 540 detects the power level required for the IP camera apparatus 110 using the time difference of the timing signal input from the IP camera apparatus 110. [ The microcomputer unit 550 supplies a continuous turn-on signal to the switching driver 530 if the power level detected by the terminal power level detector 540 is the first power level, On signal having a duty ratio of " 1 "

When the IP camera apparatus 110 becomes operable by the voltage of 48V to 56V supplied by the external power supply unit 350, the IP camera apparatus 110 receives an analog signal from the camera module, And then transmitted to the first network modem device 120 through the network transmission chip.

The first network modem device 120 converts the Ethernet packet data into an OFDM signal for a coaxial cable and outputs it to the second network modem device 130. In the second network modem device 130, the data conversion chip 322 first connects the external coaxial cable using the transformer 332 only. The data conversion chip 322 checks the reception strength of the received OFDM signal and controls the switch 338 when the reception strength is low to transmit the first impedance providing portion 334 or the second impedance providing portion 336 to the transformer 322 in parallel.

The second network modem device 130 converts the OFDM signal for the coaxial cable into digital data and outputs it to the computer 150.

The computer 150 receives the digital data transmitted from the second network modem device 130 via the LAN 160 and stores the received data in the memory.

The embodiments of the present invention described above are merely illustrative of the technical idea of the present invention, and the scope of protection of the present invention should be interpreted according to the claims. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. It should be interpreted that it falls within the scope of the right.

110: IP camera device 120: first network modem device
130: second network modem device 140: DC voltage generating device
150: computer 160: LAN
170: Coaxial cable 210: Dispenser
310: External connection unit 312: RJ-45 connector
314 coaxial connector 320 data conversion unit
321: Ethernet PHY chip 322: Data conversion chip
323: flash memory 324: DRAM
325: security button 326: analog front end chip
327: transmit filter 328: receive filter
330 impedance matching unit 332 transformer
334: First Impedance Demultiplexer 336: Second Impedance Demultiplexer
338: Switch 340: Voltage conversion unit
350 external power supply unit 510 terminal power detection unit
520: Switching part 530: Switching part
540: terminal power level detector 550:

Claims (8)

A data conversion unit for converting the digital data into an analog signal and outputting the analog signal,
An impedance matching unit for matching the analog signal output from the data conversion unit with the characteristic impedance of the coaxial cable,
A voltage conversion unit that receives a predetermined direct current voltage as an input and converts the direct current voltage into a plurality of necessary rated voltages,
And an external power supply unit for supplying the predetermined DC voltage to an external terminal device via an external LAN,
Wherein the impedance matching unit comprises: a transformer having one end connected to a transmission filter or a receiving filter of the data conversion unit and the other end connected to a coaxial connector; at least one impedance providing unit connected to the other end of the transformer; And a switch for connecting in parallel to the transformer,
The external power supply unit includes a terminal power detection unit for detecting whether or not commercial power is supplied to the external terminal apparatus and a terminal power level detection unit for detecting two or more power levels required by the external terminal apparatus Lt; / RTI > The method according to claim 1,
Wherein the data conversion unit receives Ethernet packet data as digital data from the external terminal device and outputs an OFDM signal as an analog signal. 3. The method of claim 2,
Wherein the data conversion unit includes a data conversion chip for converting the Ethernet packet data into an OFDM signal for a coaxial cable and an analog front end chip for amplifying and outputting an OFDM signal for a coaxial cable outputted from the data conversion chip Network modem device. The method of claim 3,
Wherein the data conversion unit is capable of controlling an output intensity of an OFDM signal by controlling a gain of the analog front end chip. delete delete 5. The method according to any one of claims 1 to 4,
Wherein the external power supply unit comprises: a switching unit for supplying the predetermined DC voltage to the external terminal device; a switching driver for turning on or off the switching unit; Further comprising a microcomputer for outputting a turn-on signal to the switching driver when it is determined that the commercial power is not supplied to the terminal device. 8. The method of claim 7,
Wherein the terminal power level detection unit detects a power level required for the external terminal apparatus using a time difference of a timing signal input from the external terminal apparatus.

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