Abstract: A method of detecting signal light integrity and viewability of a plurality of signal lights is performed by a signal light monitoring system including a plurality of signal light monitors coupled to the signal lights and a network interface communicator configured to interface the signal light monitors to a wireless network. The method includes receiving detection data from each signal light monitor, measuring a first measurement of signal light integrity, processing the first measurement of signal light integrity to determine at least one signal light integrity value, retrieving at least one performance requirement associated with the signal light monitors, comparing the performance requirement to the signal integrity value, determining whether each signal light monitor is compliant with the performance requirement, and propagating the compliance determination and the first measurement of signal light integrity over the wireless network via the network interface communicator.

Abstract: A tracking system includes a target unit having a GPS receiver, a signal transmitter to send a signal including a position of the target unit; and a processor to calculate an optimal time interval for transmission of the signal. A locating unit has a GPS signal receiver, a compass to provide a reference direction of the locating unit, a signal receiver to receive the signal sent by the transmitter of the target unit, a processor to calculate a range and bearing from the locating unit to the target unit, and an indicator to display the range and bearing. In certain preferred embodiments, the processor calculates a confidence level indicating the reliability of the signal being sent.