The 3M Dynatel 2273 Advanced Cable / Fault Locator is a microprocessor-based system that incorporates advanced digital signal processing techniques to quickly and efficiently locate sheath earth return) faults and trace the path of underground cables, both copper and fiber optic (with metallic trace wire). Dynatel 2273 Advanced Cable / Fault Locator receiver uses one of four user-selected locating modes – dual peak, dual null, differential or special peak (which increases the sensitivity of the receiver for tracing over longer distances). The mode is selected depending on which is most effective under the locating conditions. The receiver includes four volume settings, including a special “expander” function that makes peaks and nulls more pronounced. The expander feature enhances the amplitude difference between two conductors carrying the same signal, making the unit extremely accurate, even in congested areas.