We told them when to send a return signal to us, but no counter-message came in.

I rather expected a "Not Present" return signal, together with a message that he was out at the focus.

The return signal of the tag may still cause interference for other radio users.

She settled back to wait for the return signal.

It means that the source of the return signal is moving.

A moment later a return signal was given, and by the time he reached the side door, the dead bolt had been thrown open.

Evidently someone had thought quickly enough to set off their own return signal.

The team said they were "still hopeful" of finding a successful return signal.

The return signal continued to grow for about ten minutes.

And what if you don't ever receive this return signal?