RFM95 Datasheet, PDF (22/121 Pages) List of Unclassifed Manufacturers – Low Power Long Range Transceiver Module

WIRELESS & SENSING
RFM95/96/97/98(W)
PRELIMINARY
DATASHEET
4. RFM95/96/97/98(W) Digital Electronics
4.1. The LoRa^TM Modem
The LoRa^TM modem uses spread spectrum modulation and forward error correction techniques to increase the range and
robustness of radio communication links compared to traditional FSK or OOK based modulation. Examples of the
performance improvement possible, for several possible settings, are summarised in the table below. Here the spreading
factor and error correction rate are design variables that allow the designer to optimise the trade-off between occupied
bandwidth, data rate, link budget improvement and immunity to interference.
Table 58 Example LoRa^TM Modem Performances
Bandwidth
(kHz)
10.4
20.8
62.5
125
Spreading Factor
6
12
6
12
6
12
6
12
Coding rate
4/5
4/5
4/5
4/5
4/5
4/5
4/5
4/5
Nominal Rb
(bps)
782
24
1562
49
4688
146
9380
293
Sensitivity
indication
(dBm)
TBC
TBC
TBC
TBC
-121
-139
-118
-136
Frequency
Reference
TCXO
XTAL
For European operation the range of crystal tolerances acceptable for each sub-band (of the ERC 70-03) is given in the
specifications table. For US based operation a frequency hopping mode is available that automates both the LoRa^TM spread
spectrum and frequency hopping spread spectrum processes.
Another important facet of the LoRa^TM modem is its increased immunity to interference. The LoRa^TM modem is capable of
co-channel GMSK rejection of up to 25 dB. This immunity to interference permits the simple coexistence of LoRa^TM
modulated systems either in bands of heavy spectral usage or in hybrid communication networks that use LoRa^TM to extend
range when legacy modulation schemes fail.
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