SX1232
WIRELESS & SENSING
DATASHEET
Table 16 RssiSmoothing Options
RssiSmoothing
‘000’
Number of Samples
Estimated Accuracy
± 6dB
Response Time
2
4
‘001’
± 5dB
‘010’
8
± 4dB
(
RssiSmoothing+1
)
‘011’
16
32
64
128
256
± 3dB
2
[
ms
]
‘100’
± 2dB
4⋅ RxBw kHz
‘101’
± 1.5dB
± 1.2dB
± 1.1dB
‘110’
‘111’
The RSSI is calibrated, up the RFI pin, when Image and RSSI calibration is launched; please see section 3.5.12 for details.
3.5.4. Channel Filter
The role of the channel filter is to filter out the noise and interferers outside of the channel. Channel filtering on the SX1232
is implemented with a 16-tap Finite Impulse Response (FIR) filter, providing an outstanding Adjacent Channel Rejection
performance, even for narrowband applications.
Note to respect oversampling rules in the decimation chain of the receiver, the Bit Rate cannot be set at a higher value
than 2 times the single-side receiver bandwidth (BitRate < 2 x RxBw)
The single-side channel filter bandwidth RxBw is controlled by the parameters RxBwMant and RxBwExp in RegRxBw:
FXOSC
RxBwMant × 2RxBwExp + 2
-----------------------------------------------------------------
RxBw =
The following channel filter bandwidths are accessible (oscillator is mandated at 32 MHz):
Table 17 Available RxBw Settings
RxBwMant
(binary/value) (decimal)
RxBwExp
RxBw (kHz)
FSK / OOK
2.6
10b / 24
01b / 20
00b / 16
10b / 24
01b / 20
00b / 16
10b / 24
01b / 20
00b / 16
10b / 24
01b / 20
00b / 16
10b / 24
01b / 20
00b / 16
7
7
7
6
6
6
5
5
5
4
4
4
3
3
3
3.1
3.9
5.2
6.3
7.8
10.4
12.5
15.6
20.8
25.0
31.3
41.7
50.0
62.5
Rev 3 - August 2012
Page 29
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