The expected or assumed signal can differ radically from the perceived signal, often in surprising ways.
People spend so much energy doing things based on untrue assumptions about what others are thinking.
And this is before we even get into how much one should adjust their behavior based on someone else’s perception.
When (1) obtains we can describe this situation as one where sender and received coordinate on a message.
When (2) obtains we can say the sender acted in a way that indicative of some fact or other and the received is recognizes this; (2) can obtain when one obtains as a separate signal or when the sender hasn't intended to send a signal.
(3) obtains when the receiver attributes to the sender some expressive behavior or information that is inaccurate, say, because an interpretive schema has characterized the sender and the coding system incorrectly producing an interpretation that is false.
Else signals and signalling wouldn't be a thing and people wouldn't care for them, their reception would be a random scatter plot.