Receiver Control Register (continued)
Bit [7..5] – Receiver Baseband Bandwidth: These bits set the baseband bandwidth of the demodulated
data. The bandwidth can accommodate different FSK deviations and data rates. See Table 12 for
bandwidth configuration.
Table 12.
Baseband BW (kHz) BB2 BB1 BB0
Resvd
000
400
001
340
010
270
011
200
100
134
101
67
110
Reserved
111
Bit [4..3] – Receiver LNA Gain: These bits set the receiver LNA gain, which can be changed to
accommodate environments with high interferers. The LNA gain also affects the true RSSI value. Refer
to Bit [2..0] for RSSI. See Table 13 below for gain configuration.
Table 13.
LNA GAIN (dB)
0
-14
-6
-20
GAIN1
0
0
1
1
GAIN0
0
1
0
1
Bit [2..0] – Digital RSSI Threshold: The digital receive signal strength indicator threshold may be set to
indicate that the incoming signal strength is above a preset limit. The result is stored in bit 7 of the status
register. There are eight (8) predefined thresholds that can be set. See Table 14 below for settings.
RSSI Thresh
-103
-97
-91
-85
-79
-73
-67
-61
Table 14.
RSSI2
0
0
0
0
1
1
1
1
RSSI1
0
0
1
1
0
0
1
1
RSSI0
0
1
0
1
0
1
0
1
The RSSI threshold is affected by the LNA gain set value. Calculate the true RSSI set threshold when
the LNA gain is set to a value other than 0 dB as:
RSSI = RSSIthres + |GainLNA|
20