We are currently developing an application and want to use the CAD feature to detect LoRa signals. The goal is to stay in a low power mode for a certain time (SX1261 in sleep with data retention), then wake up, perform a CAD and if it detected a signal, go into receive mode and receive the lora frame.
The problem we are currently facing is the long “set up time” before the CAD is actually performed.
–> SX1261 wake up: 570us (instead of 340 as in data sheet)
–> SX1261 set CAD: 5ms (here, only the command SET CAD with specified opcode is sent via SPI and then it waits while the chip is busy which is most of the 5ms.)
–> SX1261 CAD operation ~150us (this time is estimated based on the current consumption measurement and makes sense (2 Symbols SF5, 500kHz = 2x64us = 128us)
–> SX1261 change to sleep: 1ms
Total energy used for this procedure: ~80uJ (which is way more then we anticipated).
Does it really take 5ms for the SX1261 before starting the CAD measurement?
Is there a way to minimize this time?