At 12.51 2012.06.18, you wrote:
>You made your ECU so you know where you are in the combustion cycle - or=20
>you can monitor the spark,
>so take your accelerometer samples mid stroke or wherever the least=20
>noise is in the stroke.

Yes, this is definitely something to experiment with, thanks.


>Also if your engine is a single cylinder 2 stroke or a 4 stroke twin at=20
>10 000 rpm,
>a processor running at 40 mips has 240 000 instructions per firing of=20
>the spark,
>you will lose time (instruction cycles) because the power stroke has a=20
>duration,
>maybe you could use that time to update a display or save a data point.

I can use timer interrupts. ;)

Cheers,
Mario


>
>Trevor Hancock
>>> what about a second accelerometer, high pass filter, invert the output
>>> and apply a proportion of it to the original accelerometer signal like
>>> active noise cancelling.  There's a Microchip ap note or reference
>>> design about active noise cancelling in a dsPIC
>>>
>>> or you might not need the second accelerometer, isolate the vibration
>>> frequency and apply the inverse...
>>>
>>> Sounds easy but I bet it's not.
>> Yes also because the MPU cannot really use much of its time in FFT filte=
ring
>> (the frequency won't be fixed, as it's linked to the RPM of the engine),=
 and
>> the frequency analysis I have made on the PC showed that it was a=20
>very complex
>> source of noise.
>>
>> Considering that the sensor wasn't going to add much functionality=20
>(but it would
>> have been cool to have), I think I'll just give up for this battle.
>>
>>
>>> Trevor Hancock
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