SX1231-31SKB915 Semtech, SX1231-31SKB915 Datasheet - Page 16

• Manufacturer Part Number: SX1231-31SKB915
• Description: TVS
• Manufacturer: Semtech

Specifications of SX1231-31SKB915

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

For operation with low modulation index signals, it is recommended that the user follows the
recommendations for setting the correct DCC bandwidth that can be found in the SX1231 datasheet.
5.3.2 LNA Gain Window
The LNA gain window provides the status of the configured LNA gain. The gain can be configured
automatically or manually. In automatic mode the LNA gain is set based upon the RSSI value. In manual
mode, the gain should be set according to the expected signal power.
Note that the AGC reference threshold is set according to:
5.3.3 AFC / FEI
The AFC / FEI (Frequency Error Indicator) window is illustrated below. Note that when AFC is activated
(either AFC auto “ON” or manually), the RF frequency in the General window of the Common
Configuration Register Tab does not update, although a measure of frequency error can be obtained by
clicking on the FEI Read button to verify correct AFC operation.
Enabling AFC low beta implements a double AFC function to offset the local oscillator of the SX1231 to
ensure that the central tone at f
the cut-off frequency of the DCC.
Please refer to the optimized set up for low modulation index systems section of the SX1231 datasheet
for further details.
5.3.4 RSSI
The RSSI window provides access to the RSSI timeout and timeout threshold functions and enable either
automatic or manual RSSI detection threshold values to be programmed. Note that the RSSI threshold
(which should not be confused with the LNA or AGC threshold) can be calculated from and equates to the
effective noise floor of the receiver for a given filter bandwidth.
Revision 3.0 – January 2010
© Semtech 2011
AgcRef
=
[
−
174
+
NF
+
10
*
log(
0
associated with low modulation index signals is not unduly attenuated by
2
*
Figure 19: LNA Gain Window
Figure 20: AFC / FEI Window
RxBw
)
Page 16 of 28
+
DemodSNR
+
FadingMarg
in
]
dBm
SX1231-31SKB
www.semtech.com
USER GUIDE