Vicon VM6093, Руководство по установке и эксплуатации

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Coaxial Cable Recommendations
Coaxial cables used to route video signals to and from the unit must meet the video recommendations in this section.
Caution: Careful selection of the proper cable is essential to obtain the best performance from this
equipment. Vicon assumes no responsibility for poor performance when cables other than those recommended
are installed. In all cases, coaxial cable impedance should be 75 ohms.
Materials
Use only cable with a pure copper center conductor. Do not use cable with either a copper-plated steel or an
aluminum center conductor because these do not transfer signals effectively in the frequency range used in CCTV
networks. A center conductor with low DC resistance is required for effective CCTV operation. Solid-core bare copper
conductor is best suited to video applications, except where flexing occurs. If the coaxial cable will be subjected to
flexing during normal use, select a cable with a stranded center conductor. The preferred dielectric material is cellular
(foam) polyethylene. It has better electrical characteristics than solid polyethylene, but is more vulnerable to moisture.
Therefore, use only solid polyethylene dielectric cable with a heavy exterior insulation in applications subject to
moisture. The shield must be copper braid providing 95% or better coverage.
Cable Types
The most commonly used cable types are RG-59/U and RG-11/U. Each is actually a family of cables with widely
varying electrical characteristics, some of which are not suitable for CCTV applications. Choose a cable type by
referring to the characteristics and maximum distances listed below. The maximum distance for best picture refers to
the distance between the camera and the unit. The characteristics of the cables in this table should be used as a
guideline when cables other than Belden are used. Materials and construction must follow the guidelines above. Note
that “BC” refers to bare copper and “TC” refers to tinned copper.
Picture Quality vs. Cable Length
Picture Quality
Maximum Cable Run* ft (m)
RG-59/U RG-6/U RG-11/U
Usable picture 1100 (350) 1500 (450) 2400 (750)
Clean picture 820 (250) 1000 (300) 1600 (500)
Best picture 400 (120) 530 (160) 820 (250)
* Longer cable runs may produce a dim, faint picture. Use a Vicon Video Amplifier to obtain a usable
picture for long cable runs.
Recommended Coaxial Cable Types
Cable Belden Alpha West Penn Type Center Type Shield and DC Resistance
Type Type No. Type No. Type No. Conductor % Coverage ohms per 1000
feet (km)
RG-11/U 8213 9847 811,4811 14 Solid BC BC braid (95%) 2.6 (8.5)
RG-6/U 9248 9804C 806,4806 18 Solid BC Foil + 61% TC 7.5 (24.6)
braid (100%)
RG-59/U 8281 9803 815 20 Solid BC 2 TC braids (96%) 9.9 (32.5)
RG-59/U 9259 ---- 816 22 Stranded BC BC braid (95%) 15.0 (49)
RG-59/U 9659 ---- ---- 22 Stranded BC BC braid (95%) 15.0 (49)
LCT1275-001A-H 02.08.06, 3:06 PM 19