Cable construction and central office re-concentration or replacement projects often require half-tapped or double-tapped placement of wire or cabling to facilitate the conversion or construction process. As part of the process of installing new cables and/or equipment, bridge taps often occur. A bridge tap is a length of wire or cable attached to normal endpoints of a circuit that introduces unwanted impedance imbalances that can interfere with data transmission.
In some instances, cables may be placed weeks or months in advance of the actual conversion or cable use. When pre-run, the cable ends are often laid in place, with one end of the new cable being connected to an existing cable and the other end left unterminated resulting in a bridge tap.
Bridge tap causes a wire to reflect signals from the unterminated end back to the source. Data signals, e.g., DSL signals, operate at high frequencies and can be severely impacted by the presence of bridge tap reflections. Circuits may operate at lowered speeds or data rates as a result of the bridge tap interference. Marginal circuits could exceed the operational limits of a design, thus entirely preventing the circuit from operating.
Accordingly, bridge taps can cause problems in operating systems. As the quality of service and attainable data rates degrade due to bridge taps, the supplier may be forced to move a customer to a lower service tier or deny services to a customer. The customer may be unsatisfied because the system no longer meets his needs. In addition, the overall system capacity loss experienced due to the bridge taps, the moving of a customer to a lower service tier, or the denial of services to a customer, may result in financial losses for both the communications service provider and the customer.
Given the negative effects of bridge tap, there exists a need for mitigating the effects of bridge tap. There is also a need for methods and apparatus for minimizing the amount of time bridge tap exists during cable and/or communications device installation which may occur during, e.g., system construction, central office re-concentration, replacement projects, upgrade projects, expansion projects, and installation of back-up cables/systems to provide reserve capacity or redundancy. At least some new methods of reducing the effects of bridge tap should be suitable for use with cables which include a large number of wires commonly used in many modern applications.