I have a problem where let's say I use ten thermocouples to measure the same air temperature. Each one gives 30 readings. What is the sample standard deviation?

Initially I would think to take all 300 data points and calculate the sample standard deviation from that, but that discounts systematic error. Unfortunately, using a spatial standard deviation discount the random error. What is the right thing to do? I know ultimately in the uncertainty I will take into account all the error sources, but I'm hung up on what the sample standard deviation should be.

Thanks.