Non-contact smart card interrogator, wherein across a transmission line from an antenna to a receiver the signal modulation varies between amplitude modulation and phase modulation

摘要

In a non-contacting smart card interrogator (1) a first end (A) of an eighth-wave transmission line (13) is connected to a terminal connecting a first receiver (16) to a transmission line (14), and to a second end (B) of the transmission line (14) the carrier wave generator (11) is connected. To the first end (A) of the eighth-wave transmission line (13) the first amplitude demodulation receiver (16) and to the second end (B) thereof a second amplitude demodulation receiver (16′) are connected. In the non-contacting smart card interrogator of the invention an effective use of amplitude demodulation is made possible by changing the phase modulation into an amplitude one by means of a passive element, whereby, however, no noise source has been introduced into the system.