Induction device employed in local loops, generally those exceeding 5,500 meters in length, that compensates for the wire capacitance and serves to boost voice grade frequencies. They are often removed for new-generation, high-speed, local-loop data services as they can distort data signals at higher frequencies than those used for voice.
A coil of wire wound around a magnetic core, which provides a lumped inductance which can be inserted in series with a cable pair to improve voice frequency transmission.
Also called Voice coils, these inductive devices used to be installed on weak phone lines in order to boost the loudness of frequencies in the range of the voice. On voice-only circuits the benefit is obvious. On modem and data circuits this device cuts the data rate of the connection. These devices are no longer used, but may be present on older lines, especially in areas that are distant from the CO.
A device used to extend the range of a local loop for voice grade communications. They are inductors added in series with the phone line which compensate for the parallel capacitance of the line. They benefit the frequencies in the high end of the voice spectrum at the expense of the frequencies above 3.6KHz. Thus, loading coils prevent DSL connections.
A metallic, doughnut-shaped device used on local loops to extend their reach.
An induction device employed in local loops exceeding 18,000 feet in length, that compensates for wire capacitance and boosts voice grade frequencies. Often removed for higher speed data services, as distortion will occur at frequencies higher than those used for voice.
In electronics, a loading coil is a coil (inductor) that does not provide coupling to any other circuit, but is inserted in a circuit to increase its inductance. The need was discovered by Oliver Heaviside in studying the disappointing slow speed of the Transatlantic telegraph cable. Previous telegraph lines were overland or shorter, hence had less capacitance, thus didn't need extra inductance.