Transmit/receive interrogator system for contactless ticket identification having transmitter level interrogated response adjusted optimising signal output level.

摘要

The contactless radio interrogation system has a first transmit/receive unit (1) transmitting radio waves to a second unit. The transmit/receive unit has a power output adjustment circuit (4) and adjuster (5). A low level signal is first sent out, and the interrogated unit then responds intermittently. The level is detected (6) allowing the output power level to be adjusted and the optimum transmitted power is then sent off.