 higher (RF) frequencies. Coaxial cable is more expensive than fibre on a per bit basis, cheaper than some types of fibre on a per metre basis but more expensive than copper particularly on a per metre basis. The most common applications today include the connection between televisions and a roof-mounted dish or antenna and/or cable TV connectivity. Twisted-pair cables were invented by Alexander Graham Bell in 1881. They are either shielded (STP) or unshielded and both conductors are floating and balanced with respect to ground and neither is connected even partially to ground. The problem with copper pairs as a lower-cost alternative to coaxial cable is that they suffer from crosstalk. This is mitigated by twisting the cables at different twist rates. They can then be bundled together without the need for shielding. This is known as an unshielded twisted Physical Layer Connectivity pair or UTP. Unshielded means the twisted pairs are unshielded from each other rather than the outside world. UTP cables are used for indoor telephone wiring, for example for phone or Ethernet con- nections, and often grouped into sets of 25 pairs within an outer sheath. Outdoor telephone cables can contain hundreds or thousands of pairs divided into bundles - the cables within each bundle have different twist rates and the bundles are then bundled together again using different twist rates. Twisted-pair copper cables are repurposed for data by adding a microfilter that ring fences the 3.4 kHz of voice bandwidth, leaving the higher frequencies to be used as a series of multiple carriers in the frequency and time domain. These higher frequencies suffer more aggressive impairments including far-end crosstalk (FEXT), near-end crosstalk (NEXT) and impulse noise. Impulse noise is typically of the order of a few microseconds and is caused by power-line transients or electromechanical switches or current surges in electrical equipment. Impulse related error rates can be reduced by forward error correction. Far-end crosstalk occurs when signa