Aim of this document is to give an overview about the possible RF settings for iM880A in LoRaTM mode, especially the frequency settings for the 868 MHz frequency band.
The iM880A is a compact, low power, bidirectional radio module for the 868 MHz frequency band using Semtech’s LoRaTM spread spectrum modulation technique. The module provides ultra-long range spread spectrum communication and high interference immunity whilst minimising current consumption. The LoRaTM modulation, in contrast to conventional modulation techniques, permits an increase in link budget and increases immunity to in-band interference. It achieves sensitivities 8 dB better than traditional FSK modulation and it also provides significant advantages in both blocking and selectivity, solving the traditional design compromise between range, interference immunity and energy consumption. In LoRaTM mode the iM880A offers three bandwidth options of 125 kHz, 250 kHz, and 500 kHz with spreading factors ranging from 7 to 12 and four different error detection and correction schemes. This provides a maximum of flexibility for user application.
Note that the spreading factor must be known in advance on both transmit and receive sides of the radio link as different spreading factors are orthogonal to each other. To further improve the robustness of the radio link iM880A provides cyclic error coding with different coding rates