Correlate the readings of an instrument, sensor, etc. with those of a standard in order to check its accuracy. Adjust experimental results to take external factors into account or to allow comparison with other data.
Questions tagged [calibration]
182 questions
25
votes
7 answers
How do we know that voltmeters are accurate?
Something that has always puzzled me is how we know the accuracy of voltmeters. From googling around, it seems that today's digital voltmeters use an ADC. An ADC works by comparing the voltage that is to be measured against a highly precise known…
John Allen
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Do digital multimeters require calibration?
This article Understanding Digital Multimeter DMM Specifications / Specs mention
A digital multimeter will only be able to meet its specifications when it is within a certain environment. Conditions such as temperature, humidity and the like will…
user275517
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19
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1 answer
Magnetometer ∞ shaped calibration
In mobile phones and other devices using a 3-axis electronic compass, a ∞/8/S shaped movement is used to calibrate the magnetometer as shown in these videos.
Why is this movement performed, what is the theory, and can anyone give some example C code…
Rick2047
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19
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2 answers
Magnetometer dynamic calibration
I am working on a Magnetometer AK8975 being a part of an IMU. Which seems to be very tricky for me. This chip gives a 3D vector as output describing earth's magnetic field at any place on earth or near it.
I tried two types of heading calculation…
Rick2047
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15
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1 answer
How does a smart phone measure battery percentage?
A smartphone (assume it to be an Android) usually displays the battery percentage from 0 to 100%. I am assuming that this is the usable capacity of the battery. I have several questions:
How exactly does it measure the remaining capacity? Assuming…
navigator
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14
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3 answers
Standard Volt and Ampere
A recent question on here asking about how to calculate the accuracy of a circuit got me thinking about calibration in general.
In particular, as EEs we routinely use volts and amperes as a unit and yet these are both rather vague and hard things to…
Trevor_G
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What makes open/short/load (OSL) calibrators so expensive/sophisticated?
An OSL that can go up to the GHZ can costs several hundreds if not thousands of dollars. What makes them so special?
My theory is that a load involves some sort of special resistor and mantaining a 50ohm load into the GHz might not be so easy, same…
S.s.
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2 answers
Why do compass chips in cellphones require frequent calibration?
Most cell phones offer digital compass functionality which uses a 3-axis magnetometer chip for data. Phones (some more than others?) frequently require the user to "recalibrate", which involves rotating the phone in a "swirly" or other pattern to…
uhoh
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11
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Is there anything particularly special about a "short" and an "open" in a VNA calibration kit?
I would like to calibrate a VNA with the reference plane at the end of a male BNC feedline. Surprisingly, female SOL kits are hard to find. There are many BNC 50-ohm loads available but I'm having trouble finding a BNC open and a BNC…
KJ7LNW
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What's the simplest way to calibrate a thermistor?
As a hobbyist who don't have access to lab equipment, it really seems impossible to me to be able to calibrate the thermistor that i have.
Of course there are calibrated temperature sensors like DS18B20, but thermistors specially on slow MCUs like…
ElectronSurf
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10
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2 answers
How to calibrate multimeters?
Without buying an expensive calibration tool, how can I accurately calibrate my multimeters?
csadam
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10
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How do you Calibrate 32.768kHz crystal for PIC24 RTCC
I'm trying to figure out the best method for PIC24 RTCC crystal calibration.
Their application note states two methods: using a lookup table and using a reference system clock.
According to them the reference system clock method is best, but they…
TiOLUWA
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9
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4 answers
How viable is it to just use 1% resistors and calibrate out the error?
At the moment, I use 0.1% resistors to get accurate voltage measurement through a voltage divider. However, the cost is high, so I was thinking of using 0.5% or 1% resistors and calibrating out the error in software by using a precision voltage…
Thomas O
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9
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What is VAR knob used for and why should it be usually in CAL position in analog scopes?
I'm trying to understand the VAR CAL uses in analog scopes.
Almost all the texts I read mention briefly about these and do not explain well.
Here are some examples:
CAUTION! There is usually a small knob marked VAR (or VARIABLE) that
allows…
user16307
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8
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How to calibrate multiple magnetometers for mass production
How would one go about calibrating several magnetometers in a production environment? The magnetometer is being used for the purposes of a compass.
Currently I'm calibrating them one-by-one in an open field free from magnetic interference (i.e.…
sam
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