Data Sheet

Page 9
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RFM95/96/97/98(W)
WIRELESS & SENSING PRELIMINARY DATASHEET
1. General Description
The RFM95/96/97/98(W) incorporates the LoRa
TM
spread spectrum modem which is capable of achieving significantly
longer range than existing systems based on FSK or OOK modulation. With this new modulation scheme sensitivities 8 dB
better than FSK can be achieved with a low-cost, low-tolerance, crystal reference. This increase in link budget provides
much longer range and robustness without the need for external amplification. LoRa
TM
also provides significant
advances in selectivity and blocking performance, further improving communication reliability. For maximum flexibility the
user may decide on the spread spectrum modulation bandwidth (BW), spreading factor (SF) and error correction rate (CR).
Another benefit of the spread modulation is that each spreading factor is orthogonal - thus multiple transmitted signals can
occupy the same channel without interfering. This also permits simple coexistence with existing FSK based systems.
Standard GFSK, FSK, OOK, and GMSK modulation is also provided to allow compatibility with existing systems or
standards such as wireless MBUS and IEEE 802.15.4g.
The RFM97 offers bandwidth options ranging from 7.8 kHz to 500 kHz with spreading factors ranging from 6 to 12, and
covering all available frequency bands. The RFM97 offers the same bandwidth and frequency band options with
spreading factors from 6 to 9. The RFM98 offers bandwidths and spreading factor options, but only covers the lower UHF
bands.
1.1. Simplified Block Diagram
Figure 1. Block Diagram