BELDEN 1694A – HDTV, SERIAL DIGITAL AND ANALOGUE VIDEO CABLE Low loss
Low-loss coaxial 75 ohm cable specifically for serial digital video signals. Industry type RG6/U
Maximum transmission distances for digital video cables
The serial digital interconnect standards are designed to operate where the signal loss at half the clock frequency does not exceed the approximate loss values:
|SMPTE 259M (PAL, widescreen):||Maximum length = 30dB loss at half the clock frequency|
|SMPTE 292M (HD-SDI 1080i):||Maximum length = 20dB loss at half the clock frequency|
|SMPTE 424M (HD-SDI 1080p):||Maximum length = 20dB loss at half the clock frequency|
|SMPTE 2081 (UHD 4K dual link):||Maximum length = 40dB loss at half the clock frequency|
|SMPTE 2082 (UHD 4K single link):||Maximum length = 40dB loss at half the clock frequency|
These differing standards explain why the maximum transmission length at 6G (UHD 4K dual link) is greater than for 3G.
This provides a method of defining the maximum calculated length of cable for satisfactory signal transmission. Interfaces such as connectors and patching may alter the overall “end-to-end” parameters as the cable is only one part of a signal path, and this also assumes installation of cables within their minimum bending radius limits and without crush effects of tie-wraps and other cable bindings that locally distort the construction profile. Having mentioned “the disclaimers”, the values shown below are a reasonable guide to what might realistically be expected in a typical professional installation.
However, these figures are the minimum distances, according to the relevant SMPTE standard. In practice, particularly with 12G, newer receiver equalisers can recover signals below the minimum levels defined in the standard, and thus enable longer run lengths. This will vary from device to device connected, and so cannot be quoted here. The bit error rate (BER) can vary dramatically as the calculated distances are approached. The BER is dependent on the receiver design and the losses in the actual coaxial cable used. Where applications are near the maximum distances shown in the table, it is recommended that distribution and routing equipment manufacturers should be contacted to verify the maximum recommended transmission distances.
|Data rate:||270Mb/s||1.5Gb/s||3Gb/s||6Gb/s||12Gb/s||Construction (1,2)|
|Specification:||SMPTE 259M||SMPTE 292M||SMPTE 424M||SMPTE 2081||SMPTE 2082|
|Application:||Component 4:3||1080i HDTV||1080p HDTV||2160p30||2160p60|
|Max. attenuation (4):||30dB||20dB||20dB||40dB||40dB|
|Belden 1505F||263m||68m||46m||60m||0.8L/3.7 flex|
|Canford SDV-F||285m||80m||51m||61m||43m||1.0L/4.8 flex|
|Canford SDV-F-R||285m||80m||51m||61m||43m||1.0L/4.8 flex|
|Canford SDV-XF||285m||80m||51m||61m||43m||1.0L/4.8 flex|
|Belden 1694F||319m||85m||57m||69m||1.0L/4.6 flex|
|Canford SDV-F-HD||323m||94m||63m||74m||50m||1.2L/4.8 flex|
|Belden 4694F||373m||96m||65m||87m||56m||1.0/4.6 flex|
- This is of the format: Centre wire diameter (mm) / Dielectric diameter (mm). Note that ‘L’ denotes a stranded centre wire.
- For stranded centre wire designs for flexible applications, there will be less copper cross-sectional area than a solid conductor of the same diameter. The centre wire or bunch diameter is relevant for connector choice. Less copper means a greater signal attenuation and hence shorter transmission distances.
- Belden do not publish maximum transmission distances at 12G for legacy digital cables. They only recommend the newer 4xxx series for 12G. Canare do not provide data for 6G.
- There may be small variations in attenuation figures between manufacturers due to the testing equipment used, particularly at the higher frequencies. This means that there can be small variations in the maximum transmission distances quoted, which are derived from the attenuation figures.
The above information has been provided by Belden Europe, Canare and Draka-Prysmian (manufacturers of the Canford SDV series cables).