Master signal generator with allied servant units to detect range between the master signal transmitter and the allied servant units

摘要

A combined radio transmitter/receiver apparatus for determining a particular distance between a transmitter and a receiver. The master transmitter unit sends a radio signal to a servant receiver. The servant receiver has a signal receiver which requires no amplification. When a signal is received from the master transmitter, it generates a current activating a comparator, which then triggers a return signal from a transmitter in the servant unit powered by a shielded battery unit. The master transmitter is set to respond either to receipt of a return signal or failure to receive a return signal. In some applications, the master transmitter will sound a warning to a user when there is no receipts of a returned signal. In other applications, the master transmitter will sound a warning to a user when there is receipt of a return signal. Through the use of tuned antennas in the master transmitter and coded return signals, false alarms and false positives are avoided.