A non-contact system suitable for measuring velocity/distance of an object travelling inside a ferromagnetic pipeline utilizes magnetic dipoles written into the pipe surface by a transmission coil. These dipoles can be detected by a magnetic detector situated a fixed distance from the transmission point. If the time taken for a dipole to travel from the transmitter to the detector is recorded then this time will be proportional to the velocity of the system. The system functions both as a velocity measurement device and as a distance marker.Once the system detects a dipole it requests a further imprint, hence, a constant spacing is maintained between dipoles equal to the spacing between transmitter and detector.