Hi Kai,

Nice to hear form you after a long time.

This is a data logger application that I am doing and the parameters of interest are not high frequency items. Mostly they are from flow meters, pressure transducers, temperature sensors and torque cells. Of these only the Torqu cells do have some high frequency component but even they are connected to well damped servo drive shafts - as such most times the signal is almost a DC.

My only concern is to present a clean signal for plotting and as well send another stream of logged data say at about 0.5 sec interval to serve as a history data to analyse if something went wrong suddenly.

Basically I need a low pass filter and I have been successful with some variants of the Butterworth. The plots are clean now. And as to extracting the trend of the signals acquired, at about 2.5KHZ and saving them to disk at 0.5 sec intervals, I am working with a smaller batch of samples - say 10 at a time - and saving the mean of those samples. Even then I get 250 samples per second - I will be happy to reach a level of 25 samples / sec without loosing the faithfulness of the original. But it is going to be not easy ??

Thanks

Raghu