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Rockbox mail archiveSubject: Re: DSP: low pass filterRe: DSP: low pass filter
From: Tomas <tomas_at_salfischberger.nl>
Date: Mon, 15 Aug 2005 21:54:00 +0200 Well... following my calculations and Dave's suggestion I have just used a 128 samples moving average, and it works great. My next problem is how to do continuous backlight dimming (not constant) but I think that's something for Miika... At the moment I have a flashing remote, activating the backlight on peaks (predefined value) on the bass channel. Tomas [IDC]Dragon wrote: >>Thanks, we got to the point that averaging is enough on IRC tonight >>too... but we had no way to calculate how many samples to average... >> >> > >I suggest using an IIR filter instead of FIR. You need way less past samples >for each step. The most simple IIR filter is like a charge/discharge (first >order lowpass): e.g. take 90% of your "charge", 10% of the new value, to get >the new charge. Play with the parameters, generalized it's n and (1-n). If >you use less of the current, the thing becomes slower, lower corner >frequency. >Power of two gives the benefit of using shift instead of multiply. Use >16 >bit for the charge. > >Jörg > > > > _______________________________________________ http://cool.haxx.se/mailman/listinfo/rockbox Received on 2005-08-15 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |