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LAB 1: ERROR ANALYSIS AND ORIENTATION
Texas A&M University
College Station, TX 77843, US.
Abstract This report is over the DAQ from how to use it to what it is used for. In this case, measuring voltage.
The DAQ records the values of voltage over a period of time to which the values are averaged to measure the
voltage. The data must also account for any errors, so we include that by taking the uncertainty and the error
propagation. Furthermore, by comparing an unknown voltage to a known voltage, properties that may influence
the result are established.
Keywords: average, uncertainty, voltage, measurement error
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1. Introduction
In this experiment, we measure the error of the voltage taken by the data acquisition unit (DAQ) from
both a known voltage and an unknown voltage. The experiment calculations are based on a large number of
samples taken over a relatively short period of time. The values and their errors are typically denoted as
x ± δ x
,
with
x
being the average of the measured values x and
δ x
as the uncertainty. That, as well as the standard
deviation
σ
and the uncertainty
δ x
or in order words the number of measurements n used to calculate the error
were calculated using the following formulas
x=
∑
i=1
n
xi
n
Equation 1
σ=
√
1
n−1∑
i=1
n
¿ ¿ ¿
Equation 2
δ x=σ
√
n
Equation 3
2. Experimental Procedure
This lab mainly focused on running the appropriate Python script with the voltage over a period of time to
take a number of samples. A Linux cheat sheet was provided to us.
To begin, we set up the DAQ by plugging it in and then made sure the correct Python script was selected.
For the known voltage, we ran Channel 3 at 8V constant voltage. The data was saved to a .csv file which we
renamed accordingly.
For the second part of the assignment including the unknown voltage, we ran the command ‘python3
mystery_voltage_daq_to_csv.py’ which collected 1000 samples without DAQ being set to any specific voltage.
We then once again saved the data as a .csv file and subsequently exported all the data collected in this lab in
order to maintain access to them.
3. Results and Analysis
The average voltages were calculated from the obtained data using Equation 1. Using these results a
scatter line was plotted between the known voltage averages and the number of samples. In Figure 1, the
voltages increased as the sample increased until the 61st sample with a voltage average of 8,097320 V. After it
hit the peak, the line decreased and the trend became steady, indicating that the voltage was stable in the
following samples after slightly declining. Figure 1 proves why the average voltage was 8.097 V as the voltage
became consistent as samples increased. After collecting 1000 samples, the average voltage was calculated to be
approaching 8.097 V with an uncertainty of ± 8.087E-6 V that was calculated by using Equations 2&3. The
scatter line in Figure 2 demonstrates a sharp declining curve since the known voltages are mostly accurate with
