Low pass filter on Analog sensors

zechdz · Post by **zechdz** » Thu Feb 09, 2017 2:40 am

I have a brake pressure sensor that I am using and I wanted to know if there is a way to use a low pass filter on the data before it is sent over telemetry.

https://podium.live/events/2017-02-08-t ... ?laps[]=50

Post by **brentp** » Fri Feb 17, 2017 7:56 pm

Yes, there is a way to specify that in the configuration, but it's not exposed in the UI, yet.

Open the configuration file and search for the field "alpha". you'll see that it's set to 1.0, which means no filtering. The lower the number, the more filtering you will see. Set it to a lower number greater than 0 and you'll be able to see the effect. 0.1 is a good starting point.

zechdz · Post by **zechdz** » Mon Feb 20, 2017 9:11 am

Ok thank you!

dewittpayne · Post by **dewittpayne** » Mon Feb 20, 2017 2:19 pm

I assume that means you're using an exponentially weighted moving average filter. The time constant of an EWMA filter is a function of sampling rate as well as alpha. A higher sampling rate gives a smaller time constant for a given alpha.