Design Of A Cable Tester For Dsl Installation Tests

摘要

Many broadband Internet service connections use standard twisted pair telephone wires and a system known as ADSL, [Asynchronous Digital Subscriber Line]. The copper wires used were only intended to carry very low frequency voice traffic, not high speed data. ADSL overcomes the frequency limitations and enables high bit rate signals to be carried. The generic term DSL is often used to include both ADSL and the new VDSL. DSL uses a modulation technique employing many different frequency signals, known as sub-carriers, each separately modulated by a portion of the digital signals. Each sub-carrier is separated by 4.3125kHz; a technique known as DMT (Discrete Multi-Tone modulation). To carry DSL the copper wires must be capable of passing these high frequency sub-carrier signals with minimal interference or degradation.