R309 AT Commands
©2015 Telegesis (UK) Ltd - 117 - AT Command Manual (Rev 3.09)
7.2 Interpreting RSSI Energy Levels
On the ETRX3 series modules the readings from AT+ESCAN represent the hexadecimal readings
from the RSSI register of the EM250 or EM35x, offset by +256 to make it a positive number;
alternatively read it as a signed 8-bit integer. AT+ESCAN returns the background radio power so
that the quietest channel can be selected for a new network; if you want to measure the RSSI of
incoming messages you must set bit C of register S10 (see page 79).
The EM35x SoCs calculate the RSSI over an 8-symbol period as well as at the end of a received
packet. They utilize the RX gain settings and the output level of the ADC within its algorithm. The
linear range of RSSI is specified to be 40dB over all temperatures. At room temperature, the linear
range is approximately 60dB (-90 dBm to -30dBm).
To Next Page
Loading...