Factors that affect ADSL

Attenuation

Attenuation is the loss of signal strength over distance during transmission. It increases with line distance, transmission power, Temperature and frequency. ADSL is a technology that hardly suffers from attenuation when the distance is increased from DSLAM to subscriber.

Bridge taps

Bridge tap is an unterminated extra length of with that connects to the local loop. Usually left over when subscriber is connected to existing pair of copper wires, and the original subscriber at the end of the pair is disconnected leaving and open-leak at the end of the wire.

When the ADSL signal is sent across the wire and it reflects through the bridges tap. The signal travels to open leak side and then bounces it back. This reflected signal is then mixed with the original signal and confuses the modem. Therefore bridge tap must be removed before install ADSL.

Cross Talk

Crosstalk is a disturbance in a wire caused by the electric or magnetic fields of other signals in other wire pairs of the same cable bundle. There are two types Crosstalk types. They are known as,

Near End Crosstalk (NEXT) is interference between two pairs in a cable measured at the same end of the cable as the transmitter.
Far end crosstalk (FEXT) is interference between two pairs of a cable measured at the other end of the cable from the transmitter.

Split pairs

Split pairs occur when one conductor is in a pair is become separated from the other conductor. They result in noise and cross talk. This will harm line condition and the quality of ADSL service.

Noise

The total power in a transmission line is made up of the signal and noise. Nose is always present but it should always be kept as low as possible in relationship to the signal. Factor that introduced noise are,

Radio and television

Transmitter

Power distribution system

Electrical Machinery

Mechanical vibrators