Patent ID: 8027761

Claim:
A locating system for providing location data to an automated lawn mower comprising: (a) a first sonic transmitter configured to generate a sonic pulse in response to receipt of a first characteristic of a radio frequency signal transmitted from said lawn mower; (b) a second sonic transmitter configured to generate a sonic pulse in response to receipt of a second characteristic of said radio frequency signal transmitted from said lawn mower; (c) a radio frequency transmitter on said lawn mower configured to produce a radio frequency signal to be received by said sonic transmitters; (d) a sonic pulse sensor on said lawn mower capable of detecting a sonic pulse transmitted from each of said sonic transmitters; (e) a counter coupled to said sonic pulse sensor to determine the time of travel of each of said sonic pulses; (f) a temperature sensor for providing ambient temperature; (g) a processor connected to said counter and said temperature sensor to calculate lawn mower x-y coordinates from input data provided by said counter and said temperature sensor; and (h) a data output connected to said processor for providing temperature corrected location data to said lawn mower; wherein said first sonic transmitter includes a positive edge detector of said radio frequency signal and said second sonic transmitter includes a negative edge detector of said radio frequency signal.