SX1276IMLTRT View Datasheet(PDF) - Semtech Corporation

Part Name

Description

Manufacturer

SX1276IMLTRT

137 MHz to 1020 MHz Low Power Long Range Transceiver

Semtech Corporation 

SX1276/77/78/79

WIRELESS, SENSING & TIMING

DATASHEET

4.1.1. Link Design Using the LoRaTM Modem

4.1.1.1. Overview

The LoRaTM modem is setup as shown in the following figure. This configuration permits the simple replacement of the

FSK modem with the LoRaTM modem via the configuration register setting RegOpMode. This change can be performed on

the fly (in Sleep operating mode) thus permitting the use of both standard FSK or OOK in conjunction with the long range

capability. The LoRaTM modulation and demodulation process is proprietary, it uses a form of spread spectrum modulation

combined with cyclic error correction coding. The combined influence of these two factors is an increase in link budget and

enhanced immunity to interference.

Figure 5. LoRaTM Modem Connectivity

A simplified outline of the transmit and receive processes is also shown above. Here we see that the LoRaTM modem has

an independent dual port data buffer FIFO that is accessed through an SPI interface common to all modes. Upon selection

of LoRaTM mode, the configuration register mapping of the SX1276/77/78/79 changes. For full details of this change

please consult the register description of Section 6.

So that it is possible to optimise the LoRaTM modulation for a given application, access is given to the designer to three

critical design parameters. Each one permitting a trade off between link budget, immunity to interference, spectral

occupancy and nominal data rate. These parameters are spreading factor, modulation bandwidth and error coding rate.

Rev. 4 - March 2015

©2015 Semtech Corporation

Page 26

www.semtech.com

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