filtering Rates

[Richard76]

Does anybody know where I can find industry standard filtering rates?

[Joel_G]

Hi Richard,

Please could you clarify your question, what kind of filtering are you thinking of doing? For instance are you filtering certain frequencies out of a signal?

Are you doing this in hardware or software, if so which hardware and software are you using?

What do you mean by filtering rates? A filter is usually continuous and will filter signals at the rate they are input.

Kind regards,

[Richard76]

Hi Joel,

Ok, I have measured some in field data to which I want to remove high level frequencies. So I am applying a low pass filter through Diadem.

The data has been measured on a sports vehicle. what I am trying to find out is what low pass filter rate I need to set at as an industry standard to look at 'g' forces encountered. For example 

to look at 'g' forces encountered on roller coasters the raw data must be filtered to 5Hz as an industry standard. filtering too low, reduces the 'g' levels due to smoothing out the data peaks  

[Joel_G]

OK I think I see what you mean.

So you want to filter out high frequency vibrations because these wouldn't actually affect a person in a car, you're more interested in the low frequency movements the would jolt someone from side to side.

I would think the roller coaster example was a good starting point, as this is quite similar to a sports car (in terms of frequency of g-forces).

If you think about the experience of being thrown from side to side in a car, at what point would you consider it to be a vibration rather than a 'g' force. That's where your filter should be, I think 5Hz or maybe slightly higher would be a good starting point (you could get thrown back and forth 5 times in a second and you probably would not consider it to be a vibration, you would probably have a bad headache).

I'm not sure if there's a specific industry standard but that's my advice.

Kind regards,

[johnsold]

Richard,

I agree with Joel's suggestions.

If there is an industry standard it would probably be in the SAE standards.  While many people who test automotive equipment use LV, going to the the SAE to look for standards is likely to be more productive.  When you know what the standard is, come back with questions about implementation.

Lynn