[android-developers] Re: Accelerometer Speaker Interference Workarounds?
On Aug 28, 7:39 pm, Robert Green rbgrn@gmail.com wrote: It's no secret that both the HTC Dream and HTC Magic have problems with sound from the built-in speaker interfering with the accelerometer. I'm currently having the problem with my new game and am not sure how I'm supposed to work around it. Quite frankly, the sound is a big part of the game and most people prefer to play with it on. I found a great way to use tilt-view control and it works really well until I turn sound on, then it all goes to crap. Sure, I could crank the sample rate up to highest and take a running average of the past 5 or so samples and pull out the outliers but it's still not very accurate. Ugh, if your observation is accurate this sounds like a system design bug. Average actually won't fully work, because the sensor needs to be low pass filtered before the analog to digital conversion, in order to keep any frequency components above its nyquist limit out of the digitizer. Otherwise you will get really odd effects if you have an audio frequency that's near a multiple of the sample rate... they can alias back to near zero frequency and look like very slow variations in reading, which would go right through your averaging. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~--~~~~--~~--~--~---
[android-developers] Re: Accelerometer Speaker Interference Workarounds?
And that's almost exactly what I see. I notice extra bad numbers coming through on certain frequencies of sound. I know I've complained about one or two things in the past but this really is a pretty bad flaw. Let's hope future devices don't have the same problems. On Aug 28, 7:56 pm, Chris Stratton cs07...@gmail.com wrote: On Aug 28, 7:39 pm, Robert Green rbgrn@gmail.com wrote: It's no secret that both the HTC Dream and HTC Magic have problems with sound from the built-in speaker interfering with the accelerometer. I'm currently having the problem with my new game and am not sure how I'm supposed to work around it. Quite frankly, the sound is a big part of the game and most people prefer to play with it on. I found a great way to use tilt-view control and it works really well until I turn sound on, then it all goes to crap. Sure, I could crank the sample rate up to highest and take a running average of the past 5 or so samples and pull out the outliers but it's still not very accurate. Ugh, if your observation is accurate this sounds like a system design bug. Average actually won't fully work, because the sensor needs to be low pass filtered before the analog to digital conversion, in order to keep any frequency components above its nyquist limit out of the digitizer. Otherwise you will get really odd effects if you have an audio frequency that's near a multiple of the sample rate... they can alias back to near zero frequency and look like very slow variations in reading, which would go right through your averaging. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~--~~~~--~~--~--~---
[android-developers] Re: Accelerometer Speaker Interference Workarounds?
it might be interesting to slowly sweep a sine wave across the audio range while plotting variation in the accelerometer reading... On Aug 28, 9:40 pm, Robert Green rbgrn@gmail.com wrote: And that's almost exactly what I see. I notice extra bad numbers coming through on certain frequencies of sound. I know I've complained about one or two things in the past but this really is a pretty bad flaw. Let's hope future devices don't have the same problems. On Aug 28, 7:56 pm, Chris Stratton cs07...@gmail.com wrote: On Aug 28, 7:39 pm, Robert Green rbgrn@gmail.com wrote: It's no secret that both the HTC Dream and HTC Magic have problems with sound from the built-in speaker interfering with the accelerometer. I'm currently having the problem with my new game and am not sure how I'm supposed to work around it. Quite frankly, the sound is a big part of the game and most people prefer to play with it on. I found a great way to use tilt-view control and it works really well until I turn sound on, then it all goes to crap. Sure, I could crank the sample rate up to highest and take a running average of the past 5 or so samples and pull out the outliers but it's still not very accurate. Ugh, if your observation is accurate this sounds like a system design bug. Average actually won't fully work, because the sensor needs to be low pass filtered before the analog to digital conversion, in order to keep any frequency components above its nyquist limit out of the digitizer. Otherwise you will get really odd effects if you have an audio frequency that's near a multiple of the sample rate... they can alias back to near zero frequency and look like very slow variations in reading, which would go right through your averaging. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~--~~~~--~~--~--~---
