Sampling square wave to workspace with an uncertain time shift (Simulink)

Hi,

I would like to sample a square wave with an uncertain time shift. The signal went through a RF system with some filters got a time offset. At the end, I'd like to sample it into a bitstream starting with the first rising edge. In Addition I would like to calculate the time offset between this edge and the start of the simulation.

Could you help me or tell me how I could get a triggered "To workspace" block?