Utility services detection
Radio frequency location (RFL)
RFL systems can be used in either passive or active modes to track known or unknown services. Buried services that do not interact with surface features (e.g. access covers or lampposts) are traced by scanning passively for their emitted signals. Background radio noise may mask any signals from such services. In passive mode (Radio and Power), the RFL detects mains and low frequency radio signals re-radiated by conductive pipes and cables. In this mode, a buried pipe or service can be accurately positioned but its depth cannot be determined. In active mode, a signal generator (operating between LF and ULF frequency bands) is used to introduce a signal onto a target pipe or cable, either by a direct connection or by inductive coupling. Active mode can be used to determine both the position and approximate depth of the target. A pipe sonde may also used in conjunction with the RFL to trace accessible non-metallic services (primarily drains) away from access chambers.
