The Received Signal Strength Indicator
(RSSI) is a measure of the RF power input
to the transceiver. The RSSI value is
based on the gain setting in the RX chain
and the measured signal level in the
channel. In RX mode, the RSSI value can
be read continuously from the RSSI status
register until the demodulator detects a
sync word (when sync word detection is
enabled). At that point the RSSI readout
value is frozen until the next time the chip
enters RX mode. If sync word detection is
disabled, the RSSI register will be
continuously updated.