A receive-only supplemental radio frequency identification (RFID) reader may receive response signals from RFID tags, digitize and interpret those signals, and transfer the resulting data to a primary RFID reader. By relieving the primary RFID reader of some or all of the tasks of receiving, demodulating, and decoding concurrent responses from multiple RFID tags, the primary RFID reader may be made less expensive and/or may devote its resources to other tasks.