As of now, I am able to read the PWM signals of the receiver using pin change interrupts on the analog pins. The last task would be to generate the required PPM signal for the simulator. I was thinking about timer interrupts to ensure, the PPM frames start at the desired time and use the remaining time of the frame for other processing tasks like reading the PWM signal. Since there is no way to run both ISR at the same, how can i guarantee, that both signals are processed error-free regarding their timings?
Dealing with interrupts is outside of my current experience level, but I'm just wondering out loud whether you might be better served using a DAC (digital-to-analog converter) and read in the value via a normal analog pin, or attach the receiver to the Arduino via SPI. It seems rather error prone to have your receiver convert a binary number into a series of PWM pulses and then have to convert those pulses back into an analog value by counting the pulses in the Arduino.