Concentricity error less than 6% Z at 20MHz it is 72.8 ohm. Core non circularity less than 6% Cladding non circularity less than 2% Attenuation Attenuation at 850nm generally less than 4dB/km Nominal attenuation at 1MHz is 8.9dB/km at 10°C. Attenuation at 1300nm generally less than 2dB/km Typical attenuation at 0.2MHz is 4.5dB/km; at 0.5MHz it is Modal bandwidth 850nm generally greater than 200MHz.km 6.5dB/km; at 5MHz it is 19.8dB/km; at 20MHz it is 39.6dB/km. Modal bandwidth 1300nm generally greater than 1000 MHz.km Chromatic dispersion 850nm generally less than 120ps/km.nm Mechanical Construction Chromatic dispersion 1300nm generally less than 6ps/km.nm Inner is solid copper wire 0.7mm diameter. Outer is 0.1mm thick copper tape, laid lengthwise. Screen is 0.1mm thick steel tape, laid lengthwise. Insulation has an external diameter of 2.9mm. Impedance Regularity 1. The optical performance quoted is for guidance only. Fibres The reflection from a 100ns pulse shall be at least 39dB down. offering 2 to 2.5dB/km at 850nm and 0.5 to 0.8dB/km are available. Similarly, bandwidths of greater than 1000MHz.km (b) Installed Cable at 850nm and 2000MHz.km at 1300nm have been achieved. The CCITT recommend specific dimensional tolerance to en- Crosstalk sure that fibres can be interconnected with an acceptably low The near-end crosstalk attenuation between coaxial pairs, loss. Provisional results indicate that acceptable splice loss and measured in the frequency band 0.5 to 20MHz on 2km or 4km adequate strength can be achieved when splicing different high- sections, should be greater than 130dB. silica fibres. Appendix 15.6 15/19 15.18 Appendix 15.6 Cladding non-circularity, less than 2% Cut off wavelength (fibre) in range 1100 - 1280nm Singlemode optical fibre cable (CCITT G.652) key Cut off wavelength (cable) less than 1270nm Loss at 1300nm less than 1dB/km (typical) parameters Dispersion (1270 - 1340nm) 6ps/km.nm max Dispersion (1550nm) 20ps/km.nm max Cladding diameter = 125um, deviation less than 2.4% Bend loss at 1550nm. 