X-Band Motion Sensor - Supply Voltage sensitivity

Mag748

Hello,
I have a Propeller and X-Band Motion sensor hooked up to a Raspberry Pi computer. The Proto Board and X-Band are receiving power from the RPi. Unfortunately, the 5V rail from the RPi fluctuates around 100mV depending on the CPU load. This really messes with the X-Bands measurements. Does anyone have any suggestions as to how I can smooth out the power? My only course of action now is to power them completely separately, but that will add a lot of extra parts.
Thanks for any input.-Marcus

kwinn

you could put a schottky diode in series with the supply and a capacitor on the x-band side of the diode. Capacitor size depends on the frequency of the 100mV ripple, but a 22uF tantalum would be a good first choice to try.