Everyone in the project is not always confused by a variety of monitoring cables? The following Xiaobian to teach everyone how to choose video monitoring cable.
Coaxial cable
Usually video signal transmission techniques using direct modulation to baseband frequency (approximately 8MHz bandwidth) form, the most common transmission medium is a coaxial cable. Coaxial cable is specially designed to transmit video signals. Its frequency loss, image distortion, and image attenuation are relatively small, which can well complete the task of transmitting video signals.
The distance from the camera to the monitoring host is ≤200 meters, usually about 100 meters. You can use SYV-75-3 (ie, RG59 line) video cable or SYV-75-5 (96 series).
The distance from the camera to the monitoring host should be >200 meters<350 meters. You can use the SYV-75-5 (128 series) video cable.
The distance from the camera to the monitoring host is about 500 meters. Basically, the SYV-75-7 can be used. (usually not commonly used)
The distance from the camera to the monitoring host is 500-1000 meters, and it can be transmitted by optical fiber.
PS: SYV cable full name solid polyethylene insulated RF coaxial cable, is a coaxial cable.
SYV-75-5: S stands for radio frequency, Y stands for polyethylene insulation, V sheath, 75 stands for characteristic impedance, 5 stands for wire diameter.
A: 64 series B: 96 series C: 128 series "edit" represents: the density of the shielding layer, that is, dense copper lines outside.
Second, the optical fiber transmission distance farther <br> <br> using optical fiber transmission, optical fiber transmission attenuation, frequency bandwidth, free from electromagnetic interference, light weight, good security series of advantages, mainly for national and provincial City-level backbone communication network, cable television network and high-speed broadband computer network. In the closed-circuit television monitoring system, optical fiber transmission has also become the preferred method for long-distance video, audio and control signal transmission.
Third, the communication cable <br> <br> a communication cable is generally used in an imaging apparatus is provided with electric head, motorized lens, install a remote decoder in use in the field. The communication transmission cable between the on-site decoder and the video matrix switching host of the control center generally uses a 2-core shielded communication cable (RVVP) or a category 3 twisted pair UTP, and each core has a cross-sectional area of ​​0.3 mm2 to 0.5 mm2. The basic principle for selecting a communication cable is that the longer the distance, the larger the wire diameter. For example: The basic communication distance that RS-485 communication stipulates is 1200m, but in actual project choose RVV2-1.5 sheath wire to expand the communication length to above 2000m. When the communication distance is too long, an RS-485 communication repeater is required.
Fourth, the twisted pair transmission <br> <br> video signal can also be used twisted pair transmission, which is to use twisted-pair transmission equipment. In some special applications, twisted pair transmission equipment is essential. For example, when a large number of twisted pairs (three or five types of wires in the standard) have been laid in the building according to the comprehensive wiring standards, and corresponding information interfaces (RJ45 or RJ11) are left in the relevant rooms, the new Increased closed-circuit television monitoring equipment does not need to re-wiring, video and audio signals and control signals can be transmitted through the twisted pair, in which the video signal transmission will use twisted pair transmission equipment. In addition, twisted-pair transmission equipment is also required for applications where twisted-pair cables (or two-core sheathed cables) have been laid and front-end camera images are transmitted to central control room equipment.
The function of the twisted pair video transmission equipment is to convert the video signal suitable for unbalanced transmission (that is, suitable for 75Ω coaxial cable transmission) to the video signal suitable for balanced transmission (that is, suitable for twisted pair transmission) at the front end; at the receiving end In contrast to the front-end processing, the video signal transmitted through the twisted pair is converted back to an unbalanced video signal.
The twisted pair transmission device itself has a video amplification effect and is therefore also suitable for long-distance signal transmission. For the above different transmission methods, the transmission components and the transmission lines used are quite different.
V. To monitor the sound listening sound
cable <br> <br> core shielded cable is generally used communication cable 4 (RVVP) or type 3 twisted pair UTP, each core cross-sectional area of 0.5mm2. In the non-interference environment, it can also be selected as unshielded twisted pair, such as commonly used in Category 5 twisted pair (4 pairs of 8 core); because the audio signal from the monitor head in the monitoring system is transmitted to the central control room is The use of point-to-point wiring, high voltage and low current transmission, so the use of non-shielded 2-core cable, such as RVV2-0.5.
Six control cable <br> <br> control cables generally refers to a head for controlling an electric multi-core cables and a variable lens, which connects to a controller or decoder pan, electric lens control terminal, The other end is directly connected to the corresponding terminals of the PTZ and the electric lens.
PTZ and controller distance ≤ 100 meters, with RVV6 × 0.5 sheath line.
The distance between the pan/tilt and the controller is more than 100 meters and the RVV6×0.75 sheath line is used.
PS: sheath line introduction: soft sheath with RVV and BVV
v-PVC insulated v-PVC sheathed R-soft VV-PVC insulated PVC sheathed power cable RVV-PVC insulated PVC sheathed flexible cable (also called sheathed wire)
Monitoring the types and differences of commonly used cables Video cable, RF cable, shielded and unshielded, signal cable, control cable, etc. Various models, initial entrants are often confused, the following is a distinction between several common models: RVV and The difference between KVV, RVVP, and KVVP: The line used in RVV and RVVP is composed of a multi-strand fine copper wire consisting of RV wires. The line used in KVV and KVVP is a hard line composed of a single strand of thick copper wire, that is, a BV line. AVVR differs RVVP: thing, but smaller than the internal cross section of 0.75 mm2 entitled AVVR, not less than 0.75 mm2 entitled RVVP.
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