A "signal" sometimes means.... 1. Wohlstetter's analogy (signals of Pear Harbor attack -- a generalization, the indicators are themselves messages transmitted by signals) 2. Inference drawn from indicators 3. Indicators, or indicators embedded in messages 4. The means of transmission 5. Messages
...and so on. The real issue seems more properly couched as salience. The blur here causes conceptual errors, and I would appreciate enlightenment, by way of an alternative taxonomy and any refs to recent papers measuring the "S/N ratio" within a channel. ~Aimee