How will the helicopter behave when the GPS signal is lost

[LupusTheCanine]

You would have to write a driver for it then tune EKF.
See

External IMU configuration

Hello, If you want to add a new external IMU, it is possible. You need to add a new backend in AP_inertialsensor and modify your hal to use it, and adapt the EKF gain for it… Quite a big work But unless you are paying a quite expensive IMU (>1000$) you won’t have much improvement… Default imu on pixhawk serie are quite good. At 1000$ it would be better to replace the whole controller … Could you details what you mean by very big error ? I fear that you are thinking that the imu is faulty whe…

For a very brief overview of the task.

PS I would start by writing a simple program to connect the unit to the PC and measure it’s accuracy and consistency to compare it’s performance to IMUs mounted on quality FC.