Embodiments herein relate to a time domain depth sensor system (100) and method for determining a depth of a ground engaging device (220) in soil. The sensor system may include a signal transmission element (104) arranged on an outer periphery of a ground engaging device that is adapted to penetrate soil. The signal transmission element can be arranged to receive and transmit an electrical signal that is responsive to impedance discontinuities detected by a pulse detector (122). The pulse detector is configured to detect a first and a second reflected signal corresponding to a sensed impedance discontinuities at a first and a second soil location. An electronic data processor (132) is communicatively coupled the pulse detector and is configured to determine the depth of the ground engaging device in the soil based on a difference between a first time of propagation of the first reflected signal and a second time of propagation of the second reflected signal.