Hi @johnstmathai, The pixhawk autopilot sofware runs on top of an RTOS. This type of sampling poses a few issues:
1: It will be hard, if not impossible to squeeze this rate of sampling out of the RTOS.
2: This rate of sampling will produce a relatively huge amount of data (12.8 Mbit) that will need to be processed and/or transferred.
3: The amount of time spent dealing with this data will interfere with the critical timing of the rest of the real-time program.
I recommend you use an independent processor to handle the sonar data.