I went for a job interview about a year ago - one of the strangest I've ever had - in which precisely such a secret vehicle tracking device was described. Appa

I went for a job interview about a year ago - one of the strangest I've ever had - in which precisely such a secret vehicle tracking device was described. Apparently they broadcast at a very low baud rate in order to reduce the amount of energy emissions which could be detected by counter-surveillance operations.