The Fisher Labs TW8800 Multi-Frequency Digital Underground Line Tracer features advance digital signal processing and additional frequencies for accurate locating. This model offers both active and passive modes for tracing and locating cables, water mains, telecommunication lines, and other subterranean utilities. Active locating utilizes both the transmitter and the receiver. By applying a signal with the transmitter, the operator can trace the path of the utility with the receiver. Different utilities respond better to different frequencies, so the TW8800 has three frequencies the operator can choose from: 82 kHz, 8.2 kHz, and 820 Hz.

The TW8800 offers four tracing methods: conductive, inductive, via coupling clamp, and passive power. The conductive method uses the accompanying transmitter to energize the buried utility by making a direct electrical connection to it with conductive tracing cables. In most cases, this method sets up the strongest magnetic field for the receiver to sense above ground. The inductive method is ideal for when a direct physical connection to the utility is unavailable. The utility may be energized indirectly by magnetically coupling an energizing current from the accompanying transmitter. The coupling clamp method is for use when a utility may be exposed, but does not provide a direct connection for the conductive tracing cables. The accessory coupling clamp can be clamped around the exposed utility to magnetically couple an energizing current from the accompanying transmitter into the utility. Passive power mode allows the TW82P-HC to detect the electric current of underground power lines and also on underground utilities that are not power lines using the Receiver as a stand-alone instrument without need for a transmitter.

The TW8800 offers audio and visual left/right guidance and depth measurement to facilitate accurate and efficient locating.