SLOS758G December 2011 – March 2020 TRF7963A
This command can be used in active mode when the RF receiver is on but RF output is off. This means bit B1 = 1 in the Chip Status Control register. The level of RF signal received on the antenna is measured and reported in the RSSI Levels register (0x0F). The relation between the 3-bit code and the external RF field strength [A/m] must be determinate by calculation or by experiments for each antenna type, because the antenna Q and connection to the RF input influence the result. Table 6-14 and Section 188.8.131.52 describe the nominal relation between the RF peak-to-peak voltage in the RF_IN1 input and RSSI code, respectively.
If the command is executed immediately after power-up and before any communication with tag was performed, the command must be preceded by the Enable RX command. The Check RF commands require full operation, so the receiver must be activated by enable RX or by a normal tag communication for the Check RF command to work properly.