RFM95 Datasheet, PDF (82/121 Pages) List of Unclassifed Manufacturers – Low Power Long Range Transceiver Module

WIRELESS & SENSING
RFM95/96/97/98(W)
PRELIMINARY
DATASHEET
Table 83 RssiSmoothing Options
RssiSmoothing
‘000’
‘001’
‘010’
‘011’
‘100’
‘101’
‘110’
‘111’
Number of Samples
2
4
8
16
32
64
128
256
Estimated Accuracy
± 6 dB
± 5 dB
± 4 dB
± 3 dB
± 2 dB
± 1.5 dB
± 1.2 dB
± 1.1 dB
Response Time
2 ^{(RssiSmoothing +1)}
4 · RxBw[kHz]
[ms]
The RSSI is calibrated when the image and RSSI calibration process is launched.
5.5.5. RSSI in LoRa^TM Mode
The RSSI values reported by the LoRa^TM modem differ from those expressed by the FSK/OOK modem. The following
formula shows the method used to interpret the LoRa^TM RSSI values.
RSSI[dBm] = –137 + RSSI
5.5.6. Channel Filter
The role of the channel filter is to reject noise and interference outside of the wanted channel. The RFM95/96/97/98(W)
channel filtering is implemented with a 16-tap finite impulse response (FIR) filter. Rejection of the filter is high enough that
the filter stop-band performance is not the dominant influence on adjacent channel rejection performance. This is instead
limited by the RFM95/96/97/98(W) PLL phase noise.
Note To respect sampling criterion in the decimation chain of the receiver, the communication bit rate cannot be set at a
higher than twice the single side receiver bandwidth (BitRate < 2 x RxBw)
The programmed single side bandwidth RxBw of the channel filter is determined by the parameters RxBwMant and
RxBwExp in RegRxBw:
RxBw
=
------------------------^F----^X----^O----^S----^C-------------------------
RxBwMant × 2^{RxBwExp + 2}
The following channel filter bandwidths are hence accessible in the case of a 32 MHz reference oscillator.
Table 84 Available RxBw Settings
RxBwMant
(binary/value)
10b / 24
01b / 20
00b / 16
10b / 24
RxBwExp
(decimal)
7
7
7
6
RxBw (kHz)
FSK / OOK
2.6
3.1
3.9
5.2
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