Texas Instruments CC112 Series, User Manual, Page: 36 / 109

CC112X/CC1175
SWRU295C Page 36 of 108
T1: The time the AGC waits after adjusting the front end gain to allow signal transients to decay
before the next signal strength measurement can take place. T1 can be calculated using Equation 13.
T2: The time the AGC uses to measure the signal strength and potentially adjust the gain. T2 can be
calculated using Equation 14.
The CS response time is the time it takes before
CARRIER_SENSE_VALID
is asserted. This is the
maximum time the radio will be in RX state when RX termination based on CS is enabled (see
Section 8.5.2 for more details). The CS response time is given by Equation 16 .
Figure 14 shows an example of how RSSI computation speed/update rate can be traded against
RSSI accuracy. In the case where
AGC_CFG0.RSSI_VALID_CNT = 00b
the number of new input
samples to the moving average filter is 2, making the CS response time short but might lead to a less
robust CS indication on the second RSSI update. In the case where
AGC_CFG0.RSSI_VALID_CNT
= 10b
(5 samples) there are no failing CS, but the response time is longer.
BB_CIC_DECFACT
9
is found in register
CHAN_BW
while
AGC_SETTLE_WAIT
and
AGC_WIN_SIZE
register fields are found in the
AGC_CFG1
register.
CARRIER_SENSE_GATE
is found in
MDMCFG1
and
DCFILT_FREEZE_COEFF
is found in
DCFILT_CFG
. The decimation factor is 20 or 32, given by the
CHAN_BW.ADC_CIC_DECFACT
register field.
XOSC
f
Factor Decimation FACT BB_CIC_DEC ) 48 _WAIT AGC_SETTLE 16 (
T1
Equation 13: T1
XOSC
f
46 Factor Decimation FACT BB_CIC_DEC 2
T2
4 ZE AGC_WIN_SI
Equation 14: T2
Configuration Register Fields/Conditions T0
CHAN_BW.CHFILT_BYPASS CHAN_BW.BB_CIC_DECFACT > 0x01
0 0 D
0
+ D
2
+ D
4
0 1 D
0
+ D
1
+ D
3
+ D
5
1 0 D
0
1 1 D
0
+ D
1
+ D
6
Table 20: T0 Matrix
9
If
BB_CIC_DECFACT
= 0, use a value of 1