To trigger both phantom camera and pixhawk cube orange plus at same time

Hello, I am using a Pixhawk cube orange plus, I want to trigger my Pixhawk cube orange plus and a phantom camera at the same time.
I was able to trigger the camera using a 5V falling edge pulse using a signal generator

Please note that the camera is outside of the system which Pixhawk has

Pixhawk is attached to a pendulum and is getting its data and the camera is capturing the pendulum

I want to be able to wirelessly trigger the Pixhawk using telemetry and do trigger for phantom at the same time with the minimum delay

Please Help

What does trigger the Pixhawk mean in this context?