Ring's sentience and Ring detection

[Gordis]

We know that evil creatures (orcs to some extent, but mostly Nazgul) were drawn to the ring. It stands to reason to suppose that the Ring, even when NOT worn, emitted some sort of “homing” signal, drawing the nazgul to it. The question is whether the Ring emitted its signal all the time, or only when it "knew" that the target (a nazgul) was nearby? And if the latter is true, then how could the Ring "know" it?

I don't think the Ring had any usual senses: sight, hearing, smell etc. More likely, it could only process the feelings of its holder – Isildur, Gollum, Bilbo, Frodo.

When Frodo saw the nazgul or knew the nazgul are (or might be) nearby, he got frightened and the Ring sensed it and started to emit its signal. When Frodo was completely unaware of the danger, even when a nazgul was really quite near, then the Ring couldn't sense the nazgul either and didn't emit its signal.

That might explain the incidents with the Gaffer (Frodo was not yet frightened at all, he even considered revealing himself to the stranger) and on the road in the Shire (there Frodo was only slightly frightened and not yet quite sure of what, and the nazgul stopped, also feeling something - but not yet sure what exactly, maybe he only smelled some hobbit flesh nearby).

The following night, Frodo was already quite frightened when he saw the nazgul, so the Ring's signal was stronger and the nazgul was much more "tuned" to the signal - he dismounted and went in the right direction. Also it has happened at night, when nazgul were more powerful. But for the Elves, Khamul would have found the Ring.

After that, the Ring, feeling Frodo's fear, must have been emitting its signal almost constantly, and indeed as we can see in the "Hunt for the Ring", published in the Reader's companion: "But [the Witch-king and Khamûl] remain watching Weathertop. Thus they become aware of the approach of Frodo on Oct. 5." And that is one day before Frodo actually reached Weathertop! Not bad...

Unfortunately the incidents that happened later (Emyn Muil, Dead Marches), are more difficult to explain. Well, perhaps there were lesser nazgul involved, whose ability to sense the Ring was no match for the WK's and Khamul's.

As for the incident in the Morgul Vale, I think it proves my theory.

First Frodo sees the WK and gets frigtened. (Here the Ring likely goes off "like a fire alarm". Then and only then the WK senses the signal and stops. (Note that the WK had time to ride from the Gates down to the Bridge before he felt anything - because Frodo was unaware of him and the Ring was not emitting).

'Even as these thoughts pierced [Frodo] with dread and held him bound as with a spell, the Rider halted suddenly, right before the entrance of the bridge, and behind him all the host stood still"

The Wk stops and tries to locate the source of the signal. Then the Ring "asks" to be put on. Frodo almost complies. But then Frodo finds Galadriel's Phial and gets shielded: As he touched it, for a while all thought of the Ring was banished from his mind. He sighed and bent his head.
Likely, as Frodo's mind becomes blank, the Ring's signal stops and the WK looses it. The Morgul Lord is in a hurry and has no time to investigate the matter - but for the war, the WK wouldn't have been deterred so easily. He had sensed the Ring all right.

Does it fit?