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rate of change question

April 15, 2007 | 7:49 pm

i am using photocells hooked up to the analogue input of a game controller which is being recognized as an hi device. i am trying to figure out a way to record when the amount of light being picked up is changing faster or slower, as in when the output of hi is changing faster i want i higher value, and a lower value when the output is changing more slowly. Basically i need a good way to track the rate of change of a signal. I have tried using the counter object and reseting at set intervals. I have also tried using the count function of the capture object. Neither of these have worked well enough. Any suggestions?


April 15, 2007 | 8:25 pm

you could use a way of calculating a mean value over a certain amount
of time (read number of values) and compare this to the new incoming
values
Of course this can only be achieved when doing a little bit slower
then realtime
I’m also pretty sure that pmpd would be a great way to look at it,
reading in basicly acceleration or decelaration.

If you would share the whole concept of the projec I would be more
then happy to help you out

best

pieter

On 15 Apr 2007, at 21:49, glong wrote:

>
> i am using photocells hooked up to the analogue input of a game
> controller which is being recognized as an hi device. i am trying
> to figure out a way to record when the amount of light being picked
> up is changing faster or slower, as in when the output of hi is
> changing faster i want i higher value, and a lower value when the
> output is changing more slowly. Basically i need a good way to
> track the rate of change of a signal. I have tried using the
> counter object and reseting at set intervals. I have also tried
> using the count function of the capture object. Neither of these
> have worked well enough. Any suggestions?
>


April 15, 2007 | 9:23 pm

Do you mean signal, as in msp signal? I’m guessing you don’t – if so,
there’s an object called tl.velocity by Trond Lossius that should do
what you want.

Alternatively, you could roll your own on the basis that rate of change
is (change in x) / (change in y) – in this case the difference between
two successive sensor readings divided by the amount of time between
them (which you can find out using the timer object).


Owen

glong wrote:
> Basically i need a good way to track the rate
> of change of a signal. I have tried using the counter object and
> reseting at set intervals. I have also tried using the count function
> of the capture object. Neither of these have worked well enough. Any
> suggestions? _______________________________________________ maxmsp
>


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