In this post I describe in details, how you can create the calibration factors for k0 ... k3 based on raw data measured with the power sensor.

Center is this XLS file. Relevant are lines 27-37.

  • Column A contains the power provided by the generator. These must be either in descending or ascending order.

  • Column B contains the raw value from the ADC (therefore we have this third screen in V1.7.1)

  • Column J contains the corrected values based on the factors k0-k3

  • Column K shows the absolute difference to the generator output level

 So now, how to get the factors k0-k3? Goto

Copy the cells O27-P37 into this field Select degree 3 and press calculate. cal1

Now you get this cal2This is one solution!

To get an idea, how the created factors match the ideal line, you can enter them into the XLS cells J24 ... M24 and you get a graph showing the deviation from the ideal line.

Using firmware 1.7.1

Enter the values k0=x^0, k1=x^1, k2=x^2, k3=x^3 into the config utility at the desired frequency line, upload and smile ;-)

Using firmware 1.8

 Copy the calculated factor into the constants table in this sketch file


and upload the recompiled sketch to the Arduino.

More details from F6ITU

Marc F6ITU has provided a more detailled description how to do the calibration on his website.


2014 CW (Morse Telegraphy) was added to the German Nationwide Inventory of Intangible Cultural Heritage.

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