US 12,308,898 B2
System and method for distinguishing between active and passive NFC devices
Tianhao Xiong, Shanghai (CN); and Gang Wu, Shanghai (CN)
Assigned to STMICROELECTRONICS (CHINA) INVESTMENT CO., LTD, Shanghai (CN)
Appl. No. 17/779,517
Filed by STMICROELECTRONICS (CHINA) INVESTMENT CO., LTD, Shanghai (CN)
PCT Filed Nov. 27, 2019, PCT No. PCT/CN2019/121170
§ 371(c)(1), (2) Date May 24, 2022,
PCT Pub. No. WO2021/102725, PCT Pub. Date Jun. 3, 2021.
Prior Publication US 2023/0021561 A1, Jan. 26, 2023
Int. Cl. H04B 5/77 (2024.01); H04B 5/79 (2024.01)
CPC H04B 5/77 (2024.01) [H04B 5/79 (2024.01)] 20 Claims
OG exemplary drawing
 
1. A method comprising:
transmitting an interrogation signal from a near field communication reader;
transmitting a carrier signal from the near field communication reader;
receiving a portion of an identification signal from a near field communication device responsive to the interrogation signal;
reducing an amplitude of the carrier signal for a selected duration after receiving the portion of the identification signal and prior to receiving an entirety of the identification signal; and
detecting whether the near field communication device continues to transmit the identification signal during the selected duration.