JP3356713B2 - Video surveillance system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video surveillance system, and more particularly to a CATV (Cable Televisio).
n) A method for monitoring upstream video transmission on a transmission line of a system.

[0002]

2. Description of the Related Art Conventionally, in a CATV system, in the case of a system using an optical transmission line, a center monitoring device 4 is connected to an optical node device 5 by an optical transmission line as shown in FIG. 4 monitors the optical node device 5.

In this case, the center monitoring device 4 has a CPU 41
To MOD (Modulator: modulator) 42 and E
The polling is performed on the optical node device 5 through the I / O (electrical / optical converter) 43 and the O / E 44 and the DEM (De
The status (normal / above) of the O / E (optical / electrical converter) 51 and the E / O 53 of the optical node device 5 is collected as data through a modulator (demodulator) 45.

Here, the optical node device 5 includes an O / E 51,
It comprises a filter 52, an E / O 53, and an SMT (status monitor) unit 6. The SMT unit 6 creates and transmits information to the center monitoring device 4.
The SMT unit 6 includes the CPU 61, the DEM 62, and the MO.
D63.

[0005]

SUMMARY OF THE INVENTION The above-mentioned conventional CAT
The V system monitors the signal level of the CATV transmission line despite the main purpose of the video service. Therefore, in order to monitor the image quality state of the most important video, the user must go to the transmission line. There is a problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a video surveillance system capable of checking a video state after light conversion without going to a transmission line and staying at a center device. .

[0007]

According to the present invention, there is provided a video surveillance system comprising: a 70-750 MHz band received from an optical transmission line ;
The video signal in the area is converted into an electric signal and the CATV (Cab
and a center device for monitoring a video signal transmitted to the optical node device. The video monitoring system includes an optical node device for transmitting a video signal to the optical node device. Folding means for folding a predetermined band of the converted video signal, and display means provided on the center device side and displaying the video signal of the predetermined band folded by the folding means , wherein the folding means comprises: Change to the electric signal
Cut out of the predetermined band of the converted video signal
A loop-back circuit to be inserted in the predetermined band.
Is set to 90 to 110 MHz .

That is, the video surveillance system of the present invention comprises:
After downstream O / E (optical / electrical) conversion in the optical node device of the CATV (Cable Television) system,
A loop-back circuit is provided which is connected to the upstream electric signal via the downstream single branching device and the band pass filter.

The pass band of the band-pass filter is set to 9
By setting the frequency to 0 to 110 MHz, it is possible to check the return image at the optical node device of down to 1 to 3 channels (channels) at the center device by utilizing the loopback circuit and the optical upstream band.

As a result, although it is not possible to check the image state of all CATVs, it is possible to check the image states of channels 1 to 3, so that the fault isolation range at the center can be dramatically improved. Becomes

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a video monitoring system according to one embodiment of the present invention. In FIG. 1, the video monitoring system according to one embodiment of the present invention includes a center facility 1, an optical node device 2, and a monitoring television (TV) 3.

The center equipment 1 includes an E / O (electric / optical) conversion unit 11 and an O / E (optical / electric) conversion unit 12.
The O-converter 11 converts the input video signal into an optical signal and sends it out to the optical transmission path, and the O / E converter 12 converts the optical signal input from the optical transmission path into a video signal and converts the Output to 3.

The optical node device 2 includes an O / E converter 21, a down-branch 1 splitter 22, and a band-pass filter (BPF) 2.
3, a filter (H, L) 24, an up-branch 1 (for insertion) 25, and an E / O converter 26.

The O / E converter 21 converts an optical signal from the optical transmission line into a video signal and outputs the video signal to the down-branch splitter 22.
The one-way down splitter 22 splits the video signal from the O / E converter 21 and outputs the split side to a band pass filter 23 and the pass side to a CATV coaxial transmission line (not shown) through a filter 24.

A band-pass filter 23 cuts out the predetermined band of the video signal branched by the down-branch 1 splitter 22, and
One-way splitter 25 for up to 3ch (channel) video signal
Let through. The up-segment splitter 25 inserts video signals (returned video) of 1 to 3 channels that have passed through the band-pass filter 23 into the signal from the CATV coaxial transmission line input through the filter 24 and sends the signal to the E / O converter 26. Send out. The E / O converter 26 converts the signal from the one-way splitter 25 for upstream into an optical signal and outputs it to the optical transmission line.

Next, the operation of the video surveillance system according to one embodiment of the present invention will be described with reference to FIG.

For example, when the video signal input of the downlink transmission path is 1 to
When a video signal of 74 ch is input, the video signal of 1 to 74 ch is transmitted to the optical node device 2 via the center equipment 1 and the optical transmission line within a band of 70 to 750 MHz.

In the optical node device 2, 1 to 74 channels
Is converted from an optical signal to an electric signal by the O / E converter 21 and then branched by the down-branch 1 splitter 22. The passing-side video signal is transmitted to the CATV coaxial transmission line through the filter 24 and is branched. The video signal on the side is sent to the band-pass filter 23. The band-pass filter 23 cuts the outside of a predetermined band (for example, 90 to 110 MHz band) of the video signal on the branch side, and outputs the video signal of 1 to 3 ch to 1 for up.
It is passed to the branching device 25.

The up-segment splitter 25 inserts the video signals of the first to third channels into the up-stream signal from the CATV coaxial transmission line input through the filter 24, and transmits the same to the E / O converter 26. The E / O converter 26 converts the upstream signal from the upstream single splitter 25 into an optical signal and outputs the optical signal to the optical transmission line.

The upstream signal converted into an optical signal by the E / O converter 26 is sent to the center equipment 1 via an optical transmission line.
The optical signal is converted into an electric signal by the O / E converter 12, and the signal is output to the monitoring television 3. As a result, it is possible to monitor the video state of the first to third channels returned by the optical node device 2.

As described above, a loopback circuit is provided in the optical node device 2 of the CATV system, which is connected to the upstream electric signal via the downstream 1 branch unit 22 and the bandpass filter 23 after the downstream O / E conversion. , Bandpass filter 23
By making the pass band of 90 to 110 MHz,
Downstream 1-3 using loopback circuit and optical upstream band
The return image of the channel can be confirmed by the center facility 1.

Therefore, although it is not possible to check the image state of all CATVs, it is possible to check the image states of channels 1 to 3, so that the fault isolation range in the center equipment 1 can be dramatically improved. The image state after the light conversion can be confirmed while staying at the center facility 1.

[0023]

As described above, according to the present invention, C
In a video surveillance system including an optical node device of an ATV system and a center device for monitoring a video signal to the optical node device, a return unit for returning a video signal of a predetermined band is provided in the optical node device, and the return unit returns the video signal. By providing the display means for displaying the video signal on the side of the center device, there is an effect that the video state after the light conversion can be confirmed without going to the transmission line and staying at the center device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a video surveillance system according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of a conventional CATV system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Center equipment 2 Optical node device 3 Monitoring television 11, 26 E / O conversion part 12, 21 O / E conversion part 22 Downlink 1 branching device 23 Bandpass filter 25 Uplink 1 branching device

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI H04N 7/18 H04B 9/00 C (56) References JP-A-4-227196 (JP, A) JP-A-5-64237 ( JP, A) JP-A-5-83708 (JP, A) JP-A-5-122706 (JP, A) JP-A-5-260471 (JP, A) JP-A 5-260472 (JP, A) JP JP-A-5-260473 (JP, A) JP-A-5-260474 (JP, A) JP-A-10-75434 (JP, A) JP-A-59-15386 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H04N 17/00-17/06

Claims (4)

(57) [Claims] 1. 70 to 750 MH received from an optical transmission line
The video signal in the z band is converted into an electric signal, and the CATV (C
1. An image monitoring system comprising: an optical node device for transmitting an optical signal to a coaxial transmission line; and a center device for monitoring a video signal transmitted to the optical node device. Folding means for folding a predetermined band of the video signal converted into
Have a display means for displaying a video signal of the predetermined band is folded in and the folded section is provided in the center apparatus side, the folded section, converts of the electrical signal
Out of the specified band of the video signal
A video surveillance system including a loopback circuit to be inserted, wherein the predetermined band is 90 to 110 MHz . 2. The loopback circuit branches a video signal converted into the electric signal, and branches one of the video signals into the CAT.
A branching unit for transmitting the signal to the V-coaxial transmission line and transmitting the other to the own circuit; a band-pass filter for cutting out a predetermined band of the other video signal branched by the branching unit; video monitoring system according to claim 1, wherein the band includes insertion means for inserting a video signal cut into upstream electric signals. 3. The center device comprises: first conversion means for converting an input video signal from the electric signal to an optical signal and sending the converted signal to the optical transmission line; 3. The video surveillance system according to claim 1 , further comprising a second conversion unit that converts an optical signal into the electric signal and sends the converted signal to the display unit. 4. An optical node device, comprising: third conversion means for converting a video signal from the center device from the optical signal into the electric signal and transmitting the electric signal to the CATV coaxial transmission line;
A fourth signal for converting an upstream signal from the CATV coaxial transmission line from the electric signal to the optical signal and transmitting the converted signal to the optical transmission line;
The video surveillance system according to any one of claims 1 to 3 , further comprising a conversion unit.