Texas Instruments CC1101 User Manual

CC1101
SWRS061H Page 47 of 98
33 show the typical RSSI readout values at the
CS threshold at 2.4 kBaud and 250 kBaud
data rate respectively. The default reset value
for CARRIER_SENSE_ABS_THR = 0 (0 dB) has
been used. MAGN_TARGET = 3 (33 dB) and 7
(42 dB) have been used for 2.4 kBaud and
250 kBaud data rate respectively. For other
data rates, the user must generate similar
tables to find the CS absolute threshold.
If the threshold is set high, i.e. only strong
signals are wanted, the threshold should be
adjusted upwards by first reducing the
MAX_LNA_GAIN value and then the
MAX_DVGA_GAIN value. This will reduce
power consumption in the receiver front end,
since the highest gain settings are avoided.
MAX_DVGA_GAIN[1:0]
00
01
10
11
MAX_LNA_GAIN[2:0]
000
-97.5
-91.5
-85.5
-79.5
001
-94
-88
-82.5
-76
010
-90.5
-84.5
-78.5
-72.5
011
-88
-82.5
-76.5
-70.5
100
-85.5
-80
-73.5
-68
101
-84
-78
-72
-66
110
-82
-76
-70
-64
111
-79
-73.5
-67
-61
Table 32: Typical RSSI Value in dBm at CS
Threshold with MAGN_TARGET = 3 (33 dB) at
2.4 kBaud, 868 MHz
MAX_DVGA_GAIN[1:0]
00
01
10
11
MAX_LNA_GAIN[2:0]
000
-90.5
-84.5
-78.5
-72.5
001
-88
-82
-76
-70
010
-84.5
-78.5
-72
-66
011
-82.5
-76.5
-70
-64
100
-80.5
-74.5
-68
-62
101
-78
-72
-66
-60
110
-76.5
-70
-64
-58
111
-74.5
-68
-62
-56
Table 33: Typical RSSI Value in dBm at CS
Threshold with MAGN_TARGET = 7 (42 dB) at
250 kBaud, 868 MHz
17.4.2 CS Relative Threshold
The relative threshold detects sudden changes
in the measured signal level. This setting does
not depend on the absolute signal level and is
thus useful to detect signals in environments
with a time varying noise floor. The register
field AGCCTRL1.CARRIER_SENSE_REL_THR
is used to enable/disable relative CS, and to
select threshold of 6 dB, 10 dB, or 14 dB RSSI
change.

Texas Instruments CC1101 Specifications

General

Brand	Texas Instruments
Model	CC1101
Category	Transceiver
Language	English