EverFocus EPHD08 Manuel d'utilisateur télécharger pdf (Page 17)

Well known signal parts such as Sync, Burst and others do not exist here.

The high frequencies do not allow a signal evaluation by standard oscilloscopes or other standard video

measurement tools. Only quite expensive HD-SDI analyzers and upscale HF - oscilloscopes could be used

here. In most cases such equipment is not available at installation site.

For this reason a careful specification of the cable type is mandatory for system planning, especially in

applications with long cable distances.

2.1.3 Cable types

The short description of HD-SDI signals above explains, why high frequency attenuation of the used video

cable has a high influence on the achievable maximum cable length. Further on also the Return Loss of the

coaxial cable and plug influences signal stability.

The standard RG-59 cable types - the most common in the CCTV industry - are originally designed for

lower frequencies.

However, due to the new optimized receiver interfaces of EverFocus HD-CCTV equipment it is also

possible to use standard RG-59 cable for distances of over 100m.

High quality, low loss RG-59 cable types allow distances up to 160m.

Longer cable distances can be achieved with low loss RG-6 or RG-11 type coaxial cables.

Generally are cable types with 75 Ω impedance required.

Attenuation at 1 GHz: < 32 dB per 100m (328 feet)

Return Loss attenuation: > 20 dB

Impedance: 75 Ω

The table below gives an orientation for achievable cable distances:

Cable Type Attenuation in dB at 1

GHz per 100 m / 328 ft

Max. Cable distance in

m ft

RG-59 24 ~ 40 * 70 ~ 160 230~520

RG-6 15 ~ 35 * 100 ~ 190 330~620

RG-11, CATV-

lowloss cables

8 ~ 16 * 180 ~< 250

590~<820

* Low quality cable may have higher attenuation

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EverFocus EPHD08 Manuel d'utilisateur Page 17