RFM98 datasheet(21/121 Pages) HOPE

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Page 21

RFM95/96/97/98(W)

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All major parameters of the RF front end and digital state machine are fully configurable via an SPI interface which gives

access to RFM95/96/97/98(W)’s configuration registers. This includes a mode auto sequencer that oversees the

transition and calibration of the RFM95/96/97/98(W) between intermediate modes of operation in the fastest time possible.

The RFM95/96/97/98(W) are equipped with both standard FSK and long range spread spectrum (LoRaTM) modems.

Depending upon the mode selected either conventional OOK or FSK modulation may be employed or the LoRaTM spread

spectrum modem.

3.1. LoRa

Modem

The LoRaTM modem uses a proprietary spread spectrum modulation technique. This modulation, in contrast to legacy

modulation techniques, permits an increase in link budget and increased immunity to in-band interference. At the same

time the frequency tolerance requirement of the crystal reference oscillator is relaxed - allowing a performance increase for

a reduction in system cost. For a fuller description of the design trade-offs and operation of the RFM95/96/97/98(W)

please consult Section 4.1 of the datasheet.

3.2. FSK/OOK Modem

In FSK/OOK mode the RFM95/96/97/98(W) supports standard modulation techniques including OOK, FSK, GFSK, MSK

and GMSK. The RFM95/96/97/98(W) is especially suited to narrow band communication thanks the low-IF architecture

employed and the built-in AFC functionality. For full information on the FSK/OOK modem please consult Section 4.2 of this

document.

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