Vicon VN-301T, Руководство по установке и эксплуатации

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Chapter 8 – Coaxial Cable RecommendationsXX159-07-00 Rev 1010 VN-301T Single-Channel Digital Video Server
Chapter 8 – Coaxial Cable
Recommendations
CAUTION: Careful selection of 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, or equivalent, are
installed. In all cases, coaxial cable impedance should be 75 ohms.
Materials
Use only a pure copper center conductor. Do not use a copper-plated steel or aluminum center conductor, as they will result in poor
quality video. Solid-core bare copper conductor is the best type, where flexing and bending will be minimal. If severe bending and flexing
is required for installation, use a stranded center conductor. Never exceed the manufacturer’s minimum bend radius specification. Use
cellular (foam) polyethylene dielectric except where heavy moisture exists. For moisture conditions, use solid polyethylene dielectric
cable with a heavy exterior insulation. The shield must be copper braid providing 95% or better coverage.
Cable Types
The cable types listed below are the most common 75-ohm types used. They vary in size (diameter), dielectric type and net DC
resistance. The larger cable results in a lower DC resistance and better video quality, with increased difficulty in handling and installation.
Let the required picture quality and cable distances provide a guide in choosing the best cable type. For cables other than the approved
Vicon types below, contact the manufacturers listed below. Note that “BC” refers to bare copper and “TC” refers to tinned copper.
Table 8-1: Recommended Coaxial Cable Types
Cable
Type
Belden
Type No.
Alpha
Type No.
West Penn
Type No.
Type Center
Conductor
Type Shield and % Coverage
DC Resistance
ohms/1000 ft (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 braid (100%) 7.5 (24.6)
RG-59/U 8281* ---- 815 20 Solid BC 2 TC braids (96%) 9.9 (32.5)
RG-59/U 9259 9803 816 22 Stranded BC BC braid (95%) 15.0 (49)
RG-59/U 9659 ---- ---- 22 Stranded BC BC braid (95%) 15.0 (49)
*Requires special BNC-M connector due to 0.305 nominal O.D.
Belden Inc. http://www.belden.com/ (800) 235-3361
Alpha Wire Company http://www.alphawire.com/ (800)-52 ALPHA (522-5742)
West Penn Wire http://www.westpenn-cdt.com/ (800)-245-4964
Table 8-2: 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)
** For longer cable runs, use a Vicon Video Amplifier to obtain a suitable picture.