copper twin wire
The copper twisted pair (CuDa) is the classic transmission medium in the access area for the subscriber line( ULL). It is a twisted pair of wires whose transmission characteristics had to be exclusively adapted to long-distance speech.
The symmetrically constructed twisted pairs are available with different impedances, namely 100 ohms, 120 ohms and 150 ohms. The twisted pairs most frequently used in Germany have an impedance of 100 ohms.
Due to the increasing requirements for new services, more efficient transmission methods have been developed, with which higher transmission speeds can be realized.
High-bit-rate transmission over the copper twisted pairs of the local loop was defined in the H specifications of the International Telecommunication Union( ITU) and ranges up to 2.32 Mbit/s with carrierless amplitude-phasemodulation( CAP).