Demo Flight Data Resolution (i.e. Sampling Rate)

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stickandrudder1
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Joined: Fri Mar 05, 2021 9:27 pm

Demo Flight Data Resolution (i.e. Sampling Rate)

Post by stickandrudder1 »

What is the default sampling rate for data collected in a Demo Recording? Is there a way to increase the frequency? I am trying to perform problem determination on a brief RPM drop at cruise power settings. While I am seeing the RPM drop on the TACH parameter on the demo file (loaded to Savvy), I am not seeing anything on EGT, Fuel Flow, etc., which would explain it. I just hoping a more frequent sampling rate might point me in the right direction.

Thanks

Paul
GRT_Jeff
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Re: Demo Flight Data Resolution (i.e. Sampling Rate)

Post by GRT_Jeff »

Demo files record all data. The EIS outputs about 12 messages per second, with the tach updating about twice per second and the other data about 5 times per second. The demo file records all 12 messages. The sampling rate of the EIS can't be changed.
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rv8ch
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Re: Demo Flight Data Resolution (i.e. Sampling Rate)

Post by rv8ch »

Hi Jeff, is there any smoothing or averaging of the data depending on the sample rate?

For example, if I have it set to 200 milliseconds and I get oil temp values of 150, 150, 100, 150, 150, this is what I see.

If during the same period, I have my sample rate to 1000 milliseconds would I have gotten a value of 150 (the last value in the 1000 millisecond interval) or 140 (the average of the 5 values in the 1000 millisecond interval)?

My reason for asking is I sometimes see zero values in my data at 200 milliseconds, and wonder if things would be better if I set a longer sample period.
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GRT_Jeff
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Joined: Tue Dec 11, 2012 12:11 am

Re: Demo Flight Data Resolution (i.e. Sampling Rate)

Post by GRT_Jeff »

No. The EFIS takes whatever values are active in memory at the time and saves those in the recording.

If your oil temp or other reading drops to zero or spikes significantly up/down for a fraction of a second every once in a while, sometimes that can be caused by electromagnetic interference getting into the EIS and affecting the EIS readings. If this is a frequent problem then you may need to investigate possible arc sources like your ignition. For milder cases adding clamp-on ferrite filters to the EIS wires may help.
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