Ramsey, Hahn echo sequence

Dear community,

I am trying to generate a Ramsey and a Hahn echo pulse as analytic function in COMSOL. Can anyone help me how to input it as an analytic function. What is the right syntax for the expression tab and the arguments? Ramsey: pi/2 and then another pi/2 pulse Hahn-echo: pi/2, then pi, then another pi/2 pulse

Thanks, BR, Astrid