Onyesi-john.abiagam@stud.hshl.de: Die Seite wurde neu angelegt: „{| class="wikitable" |- ! # !! date !! plan for this week !! Priority !! progress !! Comment |- | 1 || 28.04.26 || * Ask Mr. Ebmeyer to borrow a luxmeter as a reference (e.g. from Prof. Meyer) * Measure the values and the reference to calibrate the characteristic curve * use MATLAB regression app * compare the characteristic curve in the datasheet to the selfmade * Write your new article. || A || In Progress || *…“

2026-06-08T18:08:39Z

Die Seite wurde neu angelegt: „{| class="wikitable" |- ! # !! date !! plan for this week !! Priority !! progress !! Comment |- | 1 || 28.04.26 || * Ask Mr. Ebmeyer to borrow a luxmeter as a reference (e.g. from Prof. Meyer) * Measure the values and the reference to calibrate the characteristic curve * use MATLAB regression app * compare the characteristic curve in the datasheet to the selfmade * Write your new article. || A || In Progress || *…“

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! # !! date !! plan for this week !! Priority !! progress !! Comment
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| 1 || 28.04.26 ||
* Ask Mr. Ebmeyer to borrow a luxmeter as a reference (e.g. from Prof. Meyer)
* Measure the values and the reference to calibrate the characteristic curve
* use MATLAB regression app
* compare the characteristic curve in the datasheet to the selfmade
* Write your new [[Ambient_Light_Lux_Sensor_VEML7700|article]].
|| A || In Progress ||
* I have received the Luxmeter from Mr Ebmeyer
* Started writing the wiki article
*Data have been taken fo a fixed (Gain 1/8,Integration Time = 100ms) and graph compared to the data sheet which showed similarity but although the datasheet graph used Log-log graph but we can see similar pattern.
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| 2 || 30.04.26 ||
* Make a table for every combination of Gain an Integration Time.
* Measure the ALS raw for every kombination.
* Save the Table in your article.
* What Lux Value should be measured in which combination (Gain/IT)?
* Measure the values and the reference to calibrate the characteristic curve for every combination (Gain/IT).
* use MATLAB regression app to fit the curves.
* compare the characteristic curve in the datasheet to the selfmade
* Write your new [[Ambient_Light_Lux_Sensor_VEML7700|article]].
* Range: [0..140000] Lux
|| A || In Progress ||
* A table for every combination of Integration Time and Gain has been created and save on matlab for further analysis
* The table has been created and all the raw ALS values are entered based on every combination of the Gain and Integration Time.
*Data have been taken fo a fixed (Gain 1/8,Integration Time = 100ms) and graph compared to the data sheet which showed similarity but although the datasheet graph used Log-log graph but we can see similar pattern.
* Wiki article is updated with the data collected and the graph plotted to show their relationship
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| 3 || 06.05.26 ||
* Range: [0..140000] Lux
* Make a table for every combination of Gain an Integration Time.
* Measure the ALS raw for every combination.
* Save the Table in MATLAB.
* What Lux Value should be measured in which combination (Gain/IT)?
* Measure the values and the reference to calibrate the characteristic curve for every combination (Gain/IT).
* use MATLAB <code>Curve Fitter</code> app to fit the curves.
* compare the characteristic curve in the datasheet to the selfmade
* Write your new [[Ambient_Light_Lux_Sensor_VEML7700|article]].
* '''Reference the Luxmeter LX-1108 in the Lab L3.1-E01-130.'''
* Measure the raw sensor values without any calculation.
|| A || In Progress ||
* Table or every combination has been created
* Raw ALS for every combinations already done
* The table saved in MATLAB
* LX-1108 is already referenced with the lab Luxmeter
* Raw sensor values are measured without any calculation
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| 4 || 12.05.26 ||
* Student was confuse by the tasks.
* Tasks were discussed and minimized.
* Please work on the tasks step by step.
* Start with 1.
# '''Reference the Luxmeter LX-1108 in the Lab L3.1-E01-130.'''
# Devide the measurement range into 23 measurements e.g. <code>Ref = [0 300 600 900 1000 2000 3000 4000 5000 6000 7000 9000 10000 11000 12000 13000 14000 15000 16000 16000 18000 19000 20000]</code> Lux.
# Tune the Lamp so the reference Sensor measures them.
# Measure with the Luxmeter LX-1108 an write the results to a MATLAB array <code>LX = [0 .. 20k]</code> Lux
# Save the arrays in <code>reference.mat</code>.
# Plot the reference on x-axis and LX on y-Axis.
# Discuss the results with Prof. Schneider.
# Fit the data with a curve/regression (<code>Curve Fitter</code>).
|| A || Done ||
* The Luxmeter has been referenced in the lab
* The Measurement range divided into 21 measurements
* Measured readings written to a MATLAB array
* Arrays saved to reference.mat file
* Plot already done
* Regression used for the data
|-
| 5 || 13.05.26 ||
* Please work on the tasks step by step.
* Start with 1, 2, 3,...
# Learn how to use MATLAB (MATLAB Onramp, Core MATLAB Skills)
# Learn what a regression analysis is ([https://en.wikipedia.org/wiki/Regression_analysis URL]).
# Learn how to calculate a regression with MATLAB ([https://www.mathworks.com/help/curvefit/what-is-curve-fitting.html URL]).
# Use a textbook: e.g. [https://books.google.de/books/about/Linear_and_Nonlinear_Regression_with_Mat.html Linear and Nonlinear Regression with MATLAB]
# Learn how to calculate a relative error ([https://en.wikipedia.org/wiki/Approximation_error URL]).
# The relationship between the reference and the luxmeter appears to be a constant. This constant changes across the value range. Calculate this constant across the value range using nonlinear regression.
# Implement a function that calculates the real value from the Luxmeter measurement <code>trueLux = Lux2Ref(Lux)</code>.
# Bring your measurement data into Matlab.
# Correct the LX measurements with the function <code>Lux2Ref(Lux)</code>.
# Save the arrays in a .mat file.
# Write a MATLAB-funktion <code>ALS2Lux</code> that calculates the real lux value from the Sensor measurement.
## Automatically choose the optimal gain/IT for the measurement.
## Take the measurement with the optimal gain/IT.
## Calculate the Lux value from the ALS value.
## Go to the light-lab and validate the measurement over the range.
## Calculate the remaining relative error and display it over the range with MATLAB.
|| A || Done ||
* Done MATLAB Onramp course
* learnt Regression Analysis
* Learnt how to calculate a relative error
* The Constant across the value range is calculated using nonlinear regression
* A function is implemented to calculate real value from luxmeter measurement
* The LX measurement is corrected
* The Corrected array values is saved in a .mat file
'''Discussion on Sensor-Specific Calibration'''
* For task 11, I would like to seek clarity from my supervisor concerning which sensor he was refering to because the subsequent tasks are only specific to VEML7700 sensor
* The calibration procedure developed in the previous tasks is specific to the LX-1108 lux meter and Lab reference,It cannot be directly applied to the VEML7700 sensor.
* Unlike the LX-1108 or the lab reference luxmeter, the VEML7700 sensor measurement output depends on both the selected gain and integration time (IT) and this must be fixed before taking the measurement.
* Consequently, a unique relationship between the laboratory reference lux meter or even LX-1108 and the VEML7700 sensor cannot be established without first specifying the gain and integration-time configuration.
* The same reference lux value either from the Lab reference or the LX-1108 may produce different ALS readings under different gain and integration-time settings and finally the lux value calculated from it.
* Therefore, any reference-to-ALS-to-lux relationship derived for the VEML7700 is valid only for the specific gain and integration-time configuration used during calibration, it can not be a general function for correcting ALS.The AlS value is completely dependent on the Gain and Integration Time.
* The VEML7700 implementation codes in arduino already includes a function that automatically selects the optimal gain and integration-time combination for any current light level according VISHAY documentation.
* Therefore, the gain and integration-time optimization requested in the subsequent tasks is handled dynamically within the Arduino implementation code before the lux calculation and validation.

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Diskussion:Ambient Light Lux Sensor VEML7700 - Versionsgeschichte