Hi,
The Active Robots blurb could easily be a typo.
I doubt it. This is repeated for each of the range sensors, eg. the GP2D12
Infrared distance measuring sensor accurately determines range to target between 10cm and 80cm.
[...]
Can be used as a proximity detector to detect objects between 0cm and 130cm.
The GP2D120
Accurately determines range to target between 4cm and 30cm.
[...]
Can be used as a proximity detector to detect objects between 0cm and 50cm.
The GP2Y0A21YK
Infrared distance measuring sensor accurately determines range to target between 10cm and 80cm.
[...]
Can be used as a proximity detector to detect objects between 0cm and 130cm.
All sixty-some% longer range that should show something above noise
They can all detect down to 0cm (just not give the correct distance), but I doubt that there will be
useful proximity data at 250cm, as the beam will have spread so much that random ground reflections will come into play and would probably mean a varying signal even without an obstacle - for a small slow-ish 'bot, 2.5m is not what I'd call proximity anyway.