Abstract: A system and method for transferring historic and instantaneous diagnostic data relating to performance of an inductive loop vehicle detector 10 is disclosed and claimed. The aforementioned date is gathered over a period of time, updated and stored in a detector unit 14 forming part of the system. The stored data is then used repeatedly to modulate visible light emitted by a light emitting device 22 on the unit 14 at such a rate that the data would not be discernible to a human. The data is received by a portable data reading device 24 which is brought into optical communication with the device 22.

Abstract: A method of obtaining data relating to the performance of an inductive loop detector wherein a light source is modulated with a signal which is dependent on the data and the modulated signal is remotely detected and data extracted therefrom is stored for later processing.

Abstract: A railway detection system in which the presence of a train is detected by means of first inductive loop apparatus. When the train is detected second inductive loop apparatus is enabled to detect the passage of wheels of the train.

Abstract: An inductive loop detector which includes a detector which is coupled to the loop by means of a parallel tuned circuit and a receiver which is coupled to the loop by means of a parallel tuned circuit, with the two tuned circuits having different resonant frequencies.