Patent ID: 7511604

Claim:
A method for communicating between a reader and a plurality of RF tags, comprising the steps of: (a) transmitting a wide band broadcast interrogation signal by a reader; (b) waiting to receive said wide band broadcast interrogation signal by the plurality of RF tags; (c) upon receiving said wide band broadcast interrogation signal by a plurality of said RF tags and in response to said wide band broadcast interrogation signal transmitting a plurality of wide band response signals respectively from said RF tags, (d) receiving said wide band response signals by said reader, wherein said wide band response signals each include a sequence of pulses, wherein the duration of said pulses is much less than the time interval between said pulses wherein at least two of said wide band response signals are overlapping wide band response signals, wherein said overlapping wide band response signals are distinguishable when each of said pulses of each of said wide band response signals is detectable during the time intervals between the pulses of all other said overlapping wide band response signals; (i) detecting by said reader and thereby distinguishing said sequences of pulses of said overlapping wide band response signals (ii) estimating by said reader the number of wide band response signals transmitted by said tags in response to said wide band broadcast interrogation signal, (iii) analyzing by said reader said distinguishable wide band response signals in order to determine their round trip delay, (e) testing by said reader a predefined statistical criterion indicative of the collision probability of said wide band response signals and according to the result of said testing transmitting by said reader at least one additional wide band broadcast interrogation signal, whereby each said additional wide band broadcast interrogation signal is followed by repeating the steps of said tags said transmitting in response to said additional wide band broadcast interrogation signal and said reader receiving, detecting, estimating, analyzing, testing and transmitting at least one additional wide band broadcast interrogation signal, wherein the collision probability is based at least in part on the number of overlapping wide band response signals, the duration of said pulses and the time interval between said pluses.