INDEX without duplications

Good morning all,

I ask for your help with a measure.
I have a dataset with the following columns:

I would like to create an index based on the values ​​of a sensor. The sensor values ​​should be sorted in descending order. I managed to create the index with the RANKX function like in the following picture:

But unfortunately several sensor values ​​are repeated and the index does not continue to increase. Clearly, I would like to do as in this Excel:

Thank you in advance for your help,

Have a good day

Joel