Following the recommendations I got on my last question about troubleshooting communications in my RC car, I probed the +5V power pin of my RF 434MHz receiver module with my oscilloscope. Below is a snapshot of it.
The periods marked in red (1 & 2) are the exact moments the receiver lost connection with the transmitter. Period 1 happen right after I applied full throttle (when the voltage raised) and then let it come to a full stop. Right after that, the voltage drops and the receiver output pin goes silent (LOW) during half second. On period 2, the car is sitting still and the voltage drops spontaneously below 5V and the receiver looses connection again.
So, it's clear to me that the receiver power supply is noisy. It's varying around 100mV when the car is stopped and shows up to 200mV pp. The receiver doesn't seem to like when the voltage drops below 5.0V.
My question is: how can I make the power supply more stable for the receiver module?
I can think of two solutions:
Add a filter to the receiver +5V pin. If so, what filter circuit should I use?
Add a buck/boost voltage regulator to feed the receiver. Would this remove the ripple on the supply?