00m2 the services to be carried. This is usually the service with the highest (lettable) space from a single closet; an area of 500m2 is a better data rate. The link includes the patch panel, plugs, sockets, fly leads guideline. If the design team wishes to support a larger area from a and 100 metres of cable to make the connection. Table 33.2 Data transmission rates. (@ = under evaluation. # = used in broadcast industry.) Media level Media type Data rate (Mb/s) number Telephone cables Traditional UTP High quality UTP UTP with overall shield STP (shielded pairs) Fibre optics Network topology 33/5 This series connection is often referred to as the simplex link. The The advantage of putting it at the terminal end is that it uses the specification for this link is defined by the IEEE 802.3i standard. same lead irrespective of the type of terminal, coax, twinax, etc. The lead is then part of the structured cabling system. However, when one introduces voice into the system, telephones Table 33.3 Typical 16MHz voice and data cable tend to have fixed leads and require a Line Jack Unit (LJU) floor characteristics (UTP) socket. Locating the adaptor at the socket outlet provides the most general solution. At the modem/data concentrator end, the choices are very similar. Parameter Value/Type Locating the balun at the patch panel provides a neater installation but requires the lead to be specific, i.e. coax, twinax. Insulation PVC or LSZH Velocity factor 33.3.2 Media filters Conductor type Solid copper Some systems which have been designed for coax or screened cable Capacitance 46nF/km of a similar impedance to UTP can operate over UTP without the Insulation resistance 50 Mohms/km use of baluns. DC resistance 93 ohms/km However, to cope with the additional noise picked up by the unshielded cable, media filters must be fitted at the ends of the UTP Insertion loss 24dB/km@1MHz cable. Character impedance 100 ohms @ 1MHz 100 ohms @ 10MHz 33.3.3 Transformers 100 ohms @ 20MHz Impedance matching transformers use the effect of mutua