(a) Activation Timing.

Within 1 millisecond of entry into the reader's modulated RF field, a transponder shall be fully activated and ready to decode the polling message from the reader within 100 microseconds of receipt of a 33 microsecond long modulated RF trigger pulse from the reader.

(b) Activation Timing for Battery Power Management.

As an alternative to 1704.4(a), a delay of 20 additional milliseconds is permissible for a transponder using multiple-stage activation to conserve battery life. Within 21 milliseconds of entry into the reader's modulated RF field, such a transponder shall be fully activated and ready to decode the polling message from the reader within 100 microseconds of receipt of a 33 microsecond long modulated trigger pulse from the reader.

(c) Activation Field Strength.

The transponder receiver shall be capable of recognizing and acting on a trigger signal and polling message when the free-space field strength at the transponder location exceeds 550 mV/m and will not respond to field strengths below 450 mV/m (Electric field strengths are to be measured in free-spece and in the absence of any vehicle). After completion of the polling message, the transponder shall begin modulating and backscattering RF with continuous zero bits. 100 microseconds after completion of the polling message, the transponder shall begin transmitting its message. If a newly activated transponder does not immediately receive a polling message, it shall remain activated and ready to receive a subsequent reader message for at least 20 milliseconds.