Thermostat question

[DrFoxtrot]

I have a Siemens RDJ10RF portable thermostat that I can carry round my house to control the heating.

My question is does the little portable unit actually measure the temperature in the room it’s currently in? I was under the impression that there was a fixed temperature sensor somewhere in the house not sure where though.

I can’t find an answer on google. Someone please take pity on me and answer my embarrassingly simple question.

Mine measures the room its in

The portable thermostat will be measuring the temp in it's current location

Otherwise why would it be portable?

Thank you I thought it might be portable for the convenience of not having to get up to put the heating on.