Patent ID: 6198934
Filing Date: 2001-03-06
Classification: H04W

Abstract:
A method of judging whether a radio receiver is in a first area or a second area, said radio receiver dealing with a plurality of frequency channels, said method comprising the steps, in sequence, of:(a) receiving and demodulating radio signals;(b) detecting a synchronization signal out of the thus demodulated radio signals, and transmitting a first signal;(c) judging whether said radio receiver transfers outside a range where transmitted radio signals can be received, based on said first signal detected in said step (b);(d) detecting an intensity of electro-magnetic wave for each of said frequency channels, when said radio receiver is judged to transfer outside said range; and(e) judging that said radio receiver is situated in said first area, when all of intensities of electro-magnetic waves are equal to or smaller than a predetermined threshold value, and judging that said radio receiver is situated in said second area, when at least one of intensities of electro-magnetic waves is equal to or greater than said predetermined threshold value.