least one embodiment the induction key 300 can include a sensing module 304 a first communication module 306 a processing module 308 and a storage unit 309 electrically connected in turn the sensing module 304 can be adapted for sensing the lf signal and the magnetic field signal and starting the induction key 300 the first communication module 306 can wirelessly communicate with the computing device 20 such that the magnetic field signal sensed by the induction key 300 can be sent to the computing device 20 in at least one embodiment the first communication module 306 can be an ultra high frequency uhf signal emitter receiver the processing module 308 can provide an operational function for example the processing module 308 can calculate a magnetic field strength the storage unit 309 can provide a storage function for example the storage unit 309 can used to store an offset value the induction key 300 can further include a first codec module 305 electrically connected to the first communication module 306 the first codec module 305 can set up an identification program to validate an identification code received by the first communication module 306 if the identification code is adapted to the identification program the induction key 300 can match with the device which emit the identification code for receiving signal from the device if not the induction key 300 would not match with the device in at least one embodiment the signal source 10 can include a signal generator 13 and helmholtz coils 15 connected to the signal generator 13 the signal generator 13 can be used to generate a lf signal and output corresponding voltage to the helmholtz coils 15 the helmholtz coils 15 can generate an uniform standard magnetic field in.