Abstract: A multi-station RF thermometer and alarm system measures temperatures and/or percent relative humidity at remote locations by RF weather stations, and displays received temperature and/or other weather data telemetry on a multi-station base station that provides out-of-bounds alarm signal indications whenever temperatures are outside of user-selectable minimum and maximum values. Randomized transmission times in one embodiment and two-phase unique transmission schedules in another lessen the possibility of on-going collisions between two or more transmitters contending for the base station at the same time. Redundant data transmission lessens the possibility of environmental noise interference.

Abstract: An electronic key or other missing object locator device is responsive to the impulse characteristics of received sounds to distinguish expected impulse-like triggering sounds such as humanly produced hand claps from other impulse-like sounds such as speech or music or non-impulse-like sounds. Errors may be counted whenever the received sounds do not correspond to the expected characteristics of the expected impulse-like triggering sounds. Whenever the expected number of triggering sounds having the expected impulse characteristics have been discriminated and detected, an audible alert is sounded, provided that the errors are not too many. The device of the invention is thereby able to distinguish expected hand claps (or other humanly produced sounds) from non-intended music, speech or other impulse-like or non-impulse-like triggering sounds, rendering it operable even in noisy environments. False alarms from mechanical wave energy are prevented.