is the semimajor axis correct in this example or missing the earth radius?

I looked at this example and it lists a the altitude for Gallileo and uses it for the semimajor axis. I think it is missing the 6378 km or is there a setting which corrects it automatically in the software? https://www.mathworks.com/help/satcom/ug/modeling-constellation-using-ephemeris-data.html

https://galileognss.eu/ephemeris-keplerian-parameters/

If I put in a semimajor axis value of 6378138 m the simulation says it's valid, but 6378136 m says it crashes...

If the matlab example listed above has a error, it's quite confusing and please correct it.

Thank you

Answer 1

[Arun]

Hi Mike

I see that you seek clarification regarding whether MATLAB accounts for the inclusion of Earth’s radius when defining the semimajor axis in the example: https://www.mathworks.com/help/releases/R2021a/satcom/ug/modeling-constellation-using-ephemeris-data.html.

The semimajor axis is calculated without including Earth radius. This example was missing the inclusion of Earth radius for the semimajor axis in release R2021a. However, this has been taken care of and the example is updated to a correct value of 29599800 m since the release R2022a which was 23222000 m in release R2021a.

Please refer the documentation link for the updated example: https://www.mathworks.com/help/satcom/ug/modeling-constellation-using-ephemeris-data.html

Hope this clarification resolves the confusion.

HTH