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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 these approximate loss values:

SMPTE 259M (PAL, widescreen): Maximum length = 30dB loss at half the clock frequency
SMPTE 292M (HDTV): Maximum length = 20dB loss at half the clock frequency

This provides a method of defining the maximum calculated length of cable for satisfactory signal transmission1. 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.

Legacy test conditions 2 Updated test conditions 3
Data rate: 177Mb/s 270Mb/s 360Mb/s 1.5Gb/s 3Gb/s 6Gb/s 12Gb/s
Specification: ITU-R BT.601 SMPTE 259M SMPTE 259M SMPTE 292M SMPTE 424M SMPTE 2081 SMPTE 2082
Application: Composite PAL Component 4:3 Component 16:9 1080i HDTV 1080p HDTV 2160p30 2160p60
Belden 179DT 137m 116m 104m 34m 24m 34m
Canford SDV-M 160m 130m 135m 41m 28m
Canare L-2.5CFB 242m 199m 172m 54m 36m 49m 32m
Belden 1505F 327m 253m 223m 66m 44m 60m
Canford SDV-LFH-E 283m 255m 222m 66m 50m 67m 41m
Belden 1855A 290m 241m 207m 79m 46m 62m
Canford SDV-LFH 283m 255m 222m 66m 50m 67m 41m
Canford SDV 283m 255m 222m 66m 50m 67m 41m
Canford SDV-X-LFH 290m 255m 225m 68m 50m 67m 41m
Belden 1855ENH 316m 261m 227m 87m 52m 71m
Canford SDV-F-R 320m 280m 220m 75m 53m
Canford SDV-F 335m 280m 225m 80m 55m
Canford SDV-F-HD 319m 263m 227m 84m 56m
Belden 1694F 400m 326m 279m 87m 58m 69m
Canford SDV-I-X-LFH 405m 270m 280m 91m 64m 86m 56m
Belden 1505A 415m 338m 296m 94m 67m 87m
Canford SDV-L 477m 405m 350m 112m 70m
Canare L-5CFB 513m 420m 364m 112m 76m 42m 68m
Canford SDV-L-X-LFH 515m 430m 365m 112m 80m 107m 71m
Belden 1694A 521m 436m 378m 122m 82m 104m
Canford SDV-L-LFH 477m 405m 350m 112m 70m
Belden 7731A 756m 622m 536m 168m 110m 161m
Canford SDV-HD-LFH 700m 588m 511m 161m 120m 41m
Canford SDV-HD 700m 588m 511m 161m 120m 41m

Notes

  1. The bit error rate (BER) can vary dramatically as the calculated distances are approached. BER is dependant on the reciever design and the losses in the actual coaxial cable used.
    Distribution and routing equipment manufacturers should be contacted to verify the maximum recommended transmission distances of individual components.
  2. It is extremely important NOT to compare maximum transmission distances quoted for Belden and Canford (Draka) similar types, as the two manufacturers have entirely different policies on how they quote these parameters, which means the figures are not expressed on a 'like for like' basis. Draka take a considerably more prudent and conservative view than Belden, hence Draka figures are always lower in this table, but not in a 'like for like' comparative test using the same equipment and the same test conditions. Canford does not share the views of several other cable distributors who may only quote the 'best case' figures for the cables they sell. It is recommended to 'de-rate' best case figures by at least 10%. To further add to the problems of comparison, typical installed systems using Canford (Draka) cables can give satisfactory performance 1.5 to 1.8 times the theoretical calculated values.
  3. 6g and 12g signals are subject to the latest testing environments and therefore differ from the results of earlier standards.

The above information has been provided by Belden and Draka-Comteq (manufacturers of the Canford SDV series cables).

SDV™ is a registered trademark of Canford Audio PLC.

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