How to smooth data traces? | AEM
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rawkus
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How to smooth data traces?

Are there any options for smoothing the data? I've got lots of peaks and valleys that I would like mellowed out for some of the data. Thanks!

Dan

AEM_BB
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Which channels are you

Which channels are you referring to? Could you post a datalog or screenshot? Most of the important channels in the ECU have an adjustable smoothing filter which is found in the Setup Wizard under that sensor's configuration setup screen. 

rawkus
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I see what you're saying, I

I see what you're saying, I was hoping I could filter after the fact, other datalogging programs I've used have had that feature.

In the example below, I am trying to compare exhaust back pressure to manifold pressure and I'd love to smooth out the exhaust pressure to get a view without the peaks and valleys.

AEM_NS
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AEM BB is assuming you have

AEM BB is assuming you have an Infinity.  Maybe you do or maybe you don't.  Here's something from our old forum - I thought this had already been posted here but maybe it wasn't.

Once you have a log file loaded into AEMData, go to Data --> Edit Maths.

One the right side of the dialog box, click the “+” icon. A “Create Channel” dialog will appear. Here, you will create a new channel with uses information from another channel(s) plus a function (in this case a filter) to create a new “virtual” channel. 

Enter a name for your channel in the “Name” box. You want to differentiate this channel from your original unfiltered channel. For instance, name your new channel “Fuel Pressure Filtered” or “[F] Fuel Pressure” or similar. Under “Units”, pick the units of measure for this channel. This should match the units of the original channel. For instance, if your base channel is Fuel Pressure in PSIg, choose Pressure (Gauge) --> Pounds / Square Inch (gauge) [psi(g)]. In this screen, you can also pick a scale for the channel display, or leave “Auto Scale” checked to allow the software to visually scale the channel automatically for you.

In the drop-down menu, pick “Functions”. For this example, we will use an Averaging Filter, which is shown as “filter_avg(expr, taps)” in the Function list. You can mouse-over the filter name for a more detailed description of the function.  The “filter_avg” signifies that this is an averaging filter. “(expr, taps)” tells us how to use this function, which I will explain below. 

Double-click this function, which will add it to the math expression on the right side of the screen. Now, we will need to enter information into the parenthesis “( )” area of the function. This is where “(expr, taps)” comes into play. “expr” refers to the expression, or channel, that you would like to filter, and should be surrounded with ‘ ‘. To add a channel to this math channel, with the cursor in between the parenthesis, choose “Channels” from the drop-down list, and double-click the channel you would like to filter. This will add it to the math expression on the right side. “taps” refers to the amount of samples, or taps, that you would like to use for filtering. Start with a low value and adjust as necessary for the amount of filtering you require. A value of 5 is usually a good place to start, and results in a minimal amount of data loss. More noisy channels, especially those at high sample rates, will tend to need higher values. See the screenshot below for a finished maths channel example.

Your new math channel should now appear in your Channel List.  To change the strength of the filter after the filtered channel was already created, edit the maths function under “Edit Maths” and change the “taps” value to adjust the strength of the filter.

rawkus
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Perfect, that's exactly what

Perfect, that's exactly what I was looking for. Thanks so much!

Dan