Systems for fingerprinting digital data are described. An electronic control unit of the telephone monitors triggering of the detection circuit, to activate an emergency mode in case of such triggering and to automatically perform emergency operations in the emergency mode. Thus, a magneto-resistive effect element, a magneto-resistive effect type magnetic sensor, a magneto-resistive effect type magnetic head and a magnetic memory become able to increase a magneto-resistive change amount. When the counter for one of these units reaches a certain level, it is subdivided into sub-units, each with their own read counter, in a process that be repeated to determine frequently read word lines with a fine level of granularity while only using a relatively modest amount of RAM on the controller to store the counters. The location server receives the TOA of the first wireless signal from the first receiver and the TOA of the second wireless signal from the second receiver. A header may be appended to each data frame and would include pertinent information used to recover andor process the data frame.