choice of filter

[benco]

hello

i've got a problem:

I receive a signal (you can see in the picture), and there is a lot of noise that I don't want.

how can I get rid of this noise

I already tried with some filter but it doesn't work.

Thanx for your answers

Ben

[benco]

I forgot the picture

[devchander]

Are you measuring this signal using a DAQ card????

Rather than noise, from the pic it looks like a  0.34 V DC signal measured on a 12 bit ADC with input range +/- 10 Volts ( error of +/- 4.8 mV ):smileywink:

Is this correct??

Assuming this is correct, there are my suggestions to rectify this problem

One way to improve your measurement accuracy would be to choose an optimal ADC range ( Depends on the ADC ranges taht your DAQ card supports)

Or you could do a moving average on your samples to get a better readout

If this does not answer your query,  for a better answer please explain your situation more clearly

[winterishere8]

Moving average with 3-5 passes or a Kalman filter should fix your problem.

[benco]

thanks both of you.

devchandler, the signal comes from a DAQ-card but I can't say more because Idon't know more.

I just start my studies and I work in  Labwiev since 2 week to pay my room.

thanks Maximus00 but where can I find a moveaverage 3-5 or a kalman filter in Labview?

[devchander]

The quickest and easiest method:

Use express vi's>>signal analysis> filters

In the express vi, select filtering type as 'smoothing'

Message Edited by devchander on 09-26-2006 05:07 AM

[benco]

thanks devchandler

that's much better i hope my boss will like that

[devchander]

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benco:

i hope my boss will like that ,

---

you are hoping for the 'almost impossible'!

All the best, benco!

[benco]

hey.......

my boss said that was not so good

so I tried and tried and....... and I discovered a filter named: Median Filter PtByPt

so this filter seems good, he makes what I want except theres is a response time ( dephasing?) that i don't want

I send you a picture

I noticed that when the filter rank is high the response time is high too but the graph seems good

but when the filter rank is small the response time is small too but the graph seems not good

i just want a mix of it .a beatiful graph and a small response time

[winterishere8]

do you have sample data that you can post ?  i have a bunch of filters so if u give me sample (if possible) i can play with it or i can give you some smoothing dlls that you apply on your data