Patent ID: 6411199
Filing Date: 2002-06-25
Classification: G06K

Abstract:
A transponder reader for use in a radio frequency identification system, said system including a transponder which, in response to an interrogation signal, transmits an identification signal, said transponder reader comprising:means for producing an interrogation signal having a first RF frequency; means for receiving a transponder carrier signal having modulated thereon the identification signal, said transponder signal produces by the transponder in response to receipt of the interrogation signal; said means for receiving including an antenna, a PSK receive path disposed between said antenna and a first circuit node, an FSK receive path disposed between said antenna and said first circuit node, and a first filter for attenuating said first RF frequency disposed between said first circuit node and a second circuit node; said PSK receive path including a second filter for attenuating said first RF frequency and passing frequencies approximately one-half of said first RF frequency; said FSK receive path including a discriminator and a third filter, said third filter for attenuating frequencies approximately one-half of said first RF frequency and above and passing RF frequencies less than one-fourth of said first RF frequency.