Common problems in installation and construction of optical transceiver
2016/5/26 15:52:30
Common problems in installation and Optical Video Converter
With the development of optical fiber market, the application of optical video converter is more and more extensive, and its cost is basically the same as the cost of using cable, even lower than the cost of cable in some occasions, so the use of optical fiber transmission becomes more and more advantageous.
The following are the common problems and solutions in the installation and construction of optical transceiver provided by Hongteng optoelectronics. This paper is applicable to the use of single-mode optical cable. Common problems of optical transceiver installation are as follows:
Analog optical transceiver series
In the following cases, take one video and one reverse data optical transceiver as an example. The principle of other models is the same.
1. There is no video image, and the PTZ cannot be controlled. Possible causes of failure:
(1) the optical fiber line is blocked or the attenuation is too large.
Test method: the on-off and attenuation of optical fiber line can be measured directly by optical power meter. The measured optical power is normal if it is within - 7dB - 26dB.
(2) the optical terminals at both ends do not have normal power supply.
Test method: check the power supply. If the power supply is normal, use a multimeter to measure the on load voltage of the power interface of the optical transceiver. The normal value is about + 5V.
(3) the transmitter and receiver are reversed.
Test method: TX for transmitter, vid in for video input, Rx for receiver and vid out for video output.
2. There are video images, but the PTZ cannot be controlled.
Possible causes of failure: (1) attenuation of optical fiber line reaches critical value.
Test method: use the optical power meter to test, if the attenuation is more than 20dB, or the measured value of the optical power meter is about - 30dB.
(2) whether the dial address of decoder is consistent with the address selected by the master control device.
Test method: refer to the manual, check whether the decoder dial code is consistent with the channel selected by the master control equipment.
(3) whether the protocol selection of the master control device is consistent with that of the decoder.
Test method: check whether the agreement is consistent with the specification.
(4) check whether the data wiring is correct.
Test method: refer to the data port definition in the manual, and check whether the control line is connected reversely.
(5) the distance of the front data line is more than 150 meters.
Test method: check whether the distance between the optical transceiver of the front-end monitoring point and the decoder is more than 150 meters. If the data line is too long, it is likely to cause insufficient load capacity.
(6) too many decoders are connected to a pair of optical terminals.
Test method: the number of decoders of a pair of optical terminals shall not exceed the number of video channels of the optical terminals.
3. The video image appears rolling screen, black stripe interference, flower screen and other phenomena.
Possible causes: (1) the attenuation of optical fiber line is too large, which can be measured by optical power meter.
Test method: use optical power meter to test, and it is normal if it is less than - 25dB.
(2) the optical transceiver is interfered by strong signal source, such as strong electric field and magnetic field.
Test method: confirm whether there is such interference source around the site, and move the site for debugging.
(3) the power failure or voltage instability of the optical transceiver results in crosstalk between video channels.
Test method: replace the power supply for debugging, and install a regulated power supply. In the main control room, if conditions permit, please install a UPS power supply.
4. Sometimes there is no data control, or the pan tilt automatically rotates (485 data interface) may have fault reasons:
(1) the 485 impedance is not well matched, the load is too much, the distance of control line is too long or the wiring is not in accordance with the bus system.
Test method: 485 impedance matching is not good, too much load or control line distance is too long or the wiring is not in accordance with the bus system.
Test method: due to the high requirements of 485 protocol for impedance matching, in many engineering sites, due to the different construction wiring, impedance matching is not exactly the same, please try to use the bus system to connect the decoder, such as all according to the star connection method, it is recommended to install tc-3001 485 isolator.
5. One or more video images are not available, but the PTZ can be controlled.
Possible causes: (1) the input video signal is abnormal.
Test method: check whether the corresponding video input channel indicator light of the transmitter is on. If the video signal input is normal, the corresponding indicator light will be on. If the indicator light is not on, there is a problem with the front-end signal source.
6. When there are multiple decoders, some of them can move and some of them can't.
Possible causes of failure:
(1) the control line of the immovable decoder is wrongly connected.
Test method: check the control line.
(2) unable to move decoder dial setting error.
Test method: refer to the instruction manual.
(3) the control line of the immovable decoder is short circuited.
Test method: measure with multimeter.
(4) 485 impedance matching is not good, too much load or control line distance is too long (more than 150 meters) or wiring is not in accordance with the bus system.
Test method: if star connection is adopted, 485 isolator is recommended.
Phenomenon handling phenomenon 1: the power indicator light of the optical transceiver is not on.
Handling: check whether the modular switching power supply works normally and whether the input voltage and output voltage meet the requirements.
Phenomenon 2 video images have been displayed on the monitor, but there is a lot of noise.
Handling: the effective transmission distance of the optical fiber may have reached the limit, or the performance of the optical fiber connector may be poor or damaged.
First, use an optical power meter to measure whether the output optical power of the transmitter meets the requirements. After the optical fiber passes through the distance transmission, the optical fiber head shall be swabbed with the fine analysis flower first, and then the optical power shall be measured with the optical power meter to see whether it meets the sensitivity requirements of the optical receiver.
2. Whether the cable from signal source to optical transmitter and from optical receiver to monitor is too long.
Phenomenon 3 the camera has been turned on, the video monitor has been turned on, and the optical fiber system is also running (the power LED is on), but no image can be seen on the monitor screen.
Handling: the reason may be that the coaxial cable is connected, but the channel position is not consistent with the channel of the transmitter or receiver of the optical transceiver.
(1) at the end of the monitor, it may be a problem to replace it with a good card
