Make start and stop buttons mutually exclusive. When measurement is not running, start should be enabled and stop is disabled, and vice versa.

When measurement is running, set status text to "running" or something like this.

Investigate why status text is "Process crashed" after stop. Is the process really crashed and why? How can we fix it?

In CLI, add a way to run measurement indefinitely. For example, by specifying "--duration=inf". Use it by default in GUI.