Satellite Signal Strength Graph

 

Does anyone know what the graph colors on the satellite screen represent? The satellite signal meters can be either solid blue or transparent.

It appears that solid blue is required for navigation, but what does a transparent bar with a high signal strength represent?

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It means it hasn't locked, and/ or downloaded the latest tables.

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nüvi 3790T | nüvi 775T | Those who make peaceful revolution impossible, will make violent revolution inevitable ~ JFK