Using Arduino Nano to control Throttle

Hey, I am working on a project and got some issues. My main goal is to control the throttle channel on APM 2.8 using Arduino Nano, instead of having the receiver control it. Unfortunately, APM does not recognize or read any signal from Arduino Nano. Other channels are controlled by the receiver and work fine.
How would I go about controlling throttle via the channel using Arduino Nano, if it is possible?

How have you wired in the Rx and the Nano?
Does the APM take a single PPM signal or individual PWM signals?
A few more details would help.
What are you running on the Nano?
Output from the Nano?

Found the solution. APM frequency was different from arduino pin frequency, but thanks for help.