That is BEAMING. I said that a spherical wave front can not be detected.
Read my post again:
"Only an extremely narrow beam could be seen against the noise produced by the central star of the system. Huge antenna gain (narrowness of beam) is required to offset the huge power advantage of the central star relative to the signalling device."
It is EASY to detect a narrowly beamed signal of a few hundred megawats. It WILL indeed outshine the parent star at its target system. It need not be simply turned on and off once in a while. One nanobaud is a reasonable bandwidth with zero loss of information at a thousand light years, providing that the source laser is reasonably powerful and the beam is sufficiently narrow.