RFID reader systems, chips, and methods deal with the occasional problem of environmental noise, such as interference from other RFID readers. An RF carrier at a center frequency is modulated, for causing an antenna to transmit a wireless signal to an RFID tag. One of a first and a second stored code modules is selected, such as by a selector. The code modules are each associated with a format, referenced to the center frequency, of a backscatter response of the RFID tag to the transmitted wireless signal, where the first code module is associated with a baseband modulation format, and the second code module is associated with a subcarrier modulation format. The transmitted wireless signal includes a command instructing the tag to backscatter according to the format of the selected code module. In addition, a wireless signal that is backscattered from the RFID tag in response to the command is demodulated according to the format of the selected code module.