Translating the accuracy rating of an electronic measurement device

[ttrager]

Many times I see a straight forward +/- in inches or metric. E.g. Accuracy stated as .000080

However, sometimes OEM's have a formula for their Accuracy rating, and I'm just not sure how to translate that to something like the above.

For instance: ±(32+20L)µin (±0.8+0.02L)µm

I believe "L" is linear length.

At any rate, anyone with a tip on how to translate that type of accuracy spec, thanks in advance.

 

[Conrad Hoffman]

The further you go the more cumulative error, so it's just as you describe. The only pitfall is knowing the units for "L"- even though the overall error might be in microinches, "L" is in inches. The translation is fine, but has to be stated for the length you used. There's no all encompassing number like your first example.

 

[ttrager]

The further you go the more cumulative error, so it's just as you describe. The only pitfall is knowing the units for "L"- even though the overall error might be in microinches, "L" is in inches. The translation is fine, but has to be stated for the length you used. There's no all encompassing number like your first example.

Ok. I appreciate the response.

 

[eKretz]

Most any accuracy rating I've seen takes into account the amount of units being measured. Whether that's length, digital count, etc. Any rating otherwise is probably not very truthful/accurate or only over a very short span.

 

[John Garner]

The quick-and-dirty way to look at that type of specification is the constant term is error in the scale reading system, and the length-dependent term is error in the scale itself.

 

[Tony Quiring]

If digital there is the last statement regarding display.

Regardless of resolution, the accuracy is good to +/- one count.

The display will round off to get last digit.

Next, sometimes the last digit is only a "0" or "5"...

Digital displays allow for great accuracy, but back in the electronics class the folks with the digital display on power supply or DVM took a lot longer to complete same task as they would chase that last digit while the rest of us set per the needle on the meter and got by .

How accurate do you need?

Does your measurement equipment have 10x better accuracy?

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