Refactored version of GhostScanner by Optera which is a refactored version of Construction Signaler by codekitchen.
Overhauled the code to be better scalable for larger maps. Overall it runs a lot smoother and through settings the impact on performance changes noticeably.

Usage:

• Unlocks with circuit network research.
• Place it in the logistics (orange) area of a roboport so it knows where to look for ghosts.

Features:

• reads entity ghosts
• reads tile ghosts
• reads item requests (modules) from ghosts
• reads item requests (modules) from built entities
• reads items required for upgrades
• reads cliff explosives required (can not account for optimization by construction bot logic)
• reads number of logistics cells (can be turned off in map settings)
• optimized performance as much as possible (having to use find_entities will always be a major drain)
• holding a scanner shows logistic network coverage
• Ghost scanners can be turned on and off individually
• Turned off scanners have almost no performance impact (still need to check if it's on or off)
• automatic migration from previous GhostScanner mod

Runtime Settings:

• Scanned sections per tick
  number of logistic network sub-areas that are scanned per tick, reducing number greatly reduces performance impact
• Update frequency
  minimum time between scanner updates. increasing time will reduce load slightly
• Scan Result limit
  counters performance drops during large build projects by limiting how many ghosts are found
  The same mechanism is used in base game for the notification icon.
  Set to 0 to disable.
• Invert output
  saves an inverting combinator when used for LTN requests
• Round to stacks
  Rounds item counts up (down with Invert output) to next full item stack.