What is meant by sensitivity?
Let's start by defining terms using the mk. 1 eyeball as our sensor.
The object to be sensed is defined as a 100 dt sphere starship with Jump 1 1g and thruster plates and antigravity and G-comp installed.
So we have a 13.9 approx. diameter black ball.
We need to have Sensitivity + signature - range >0 to have any chance to see it and a 2.5 to automatically see it.
visible signature assumes it is being illuminated by the local star.
so range 1 is 1 meter, range 2 is 10 meters, range 3 is 100 meters and so on.
We can determine that the ship is automatically spotted to range 3 range 4 is easy range 5 is hard and you are not going to spot it at range 6 (100km), so that puts the sensitivity of the mk. 1 eyeball at 6.0 or less.
That was in full daylight, let's put the thing in shadow, it's now night and the moon's not up, can we see it 1 meter away? well it occludes stars across 60 degrees of our vision so yes we can see it by what it obscures. 10 meters away, still yes, 50 meters? and we have a chance of not seeing it.
so signature -2.5 - range 2.5 = -5 + sensitivity 6 means a standard task of difficult.
What about fog? if we have a modifier to vision of -1 due to haze/light mist then 1km in daylight becomes our limit.
So there is the example of seeing something. Signature may be modified by not being illuminated, or there may be other items obscuring the signal (clouds, dust, planetary atmosphere), the signal may also be blended in with the background. (truck with a bank of lights mounted on it and shining becomes invisible when it is in the line of sight to the sun, by providing light that would have been blocked by the truck)
The FF&S design sequences show PEMS starting at 12.5 sensitivity, but what does that mean?
How far away can I detect the standard ship mentioned above? and Tgt lock?
Sensitivity range
1 1m
2 10m
3 100m
4 1km
5 10km
6 100km
7 1000km
8 10,000km
9 100,000km (3 1/3 hexes)
9.5 500,999km (16.65 hexes) Auto
10 1 million m (33 1/3) easy
11 10 million m (333 hexes) difficult
12 100 million meters (3,333 hexes) Impossible
12.5 500 million m (16665 hexes) No chance
So now instead of being illuminated by the sun it's hiding behind an asteroid and has been powered off for weeks:
(Vis sig -2.5) (IR sig -2) (Active sig no change)
Our auto points are in the same hex at 7.5 for visible, and 8 for IR, so our no chance point moves to 165 hexes and the impossible level task is at 33 hexes.
Let's start by defining terms using the mk. 1 eyeball as our sensor.
The object to be sensed is defined as a 100 dt sphere starship with Jump 1 1g and thruster plates and antigravity and G-comp installed.
So we have a 13.9 approx. diameter black ball.
We need to have Sensitivity + signature - range >0 to have any chance to see it and a 2.5 to automatically see it.
visible signature assumes it is being illuminated by the local star.
so range 1 is 1 meter, range 2 is 10 meters, range 3 is 100 meters and so on.
We can determine that the ship is automatically spotted to range 3 range 4 is easy range 5 is hard and you are not going to spot it at range 6 (100km), so that puts the sensitivity of the mk. 1 eyeball at 6.0 or less.
That was in full daylight, let's put the thing in shadow, it's now night and the moon's not up, can we see it 1 meter away? well it occludes stars across 60 degrees of our vision so yes we can see it by what it obscures. 10 meters away, still yes, 50 meters? and we have a chance of not seeing it.
so signature -2.5 - range 2.5 = -5 + sensitivity 6 means a standard task of difficult.
What about fog? if we have a modifier to vision of -1 due to haze/light mist then 1km in daylight becomes our limit.
So there is the example of seeing something. Signature may be modified by not being illuminated, or there may be other items obscuring the signal (clouds, dust, planetary atmosphere), the signal may also be blended in with the background. (truck with a bank of lights mounted on it and shining becomes invisible when it is in the line of sight to the sun, by providing light that would have been blocked by the truck)
The FF&S design sequences show PEMS starting at 12.5 sensitivity, but what does that mean?
How far away can I detect the standard ship mentioned above? and Tgt lock?
Sensitivity range
1 1m
2 10m
3 100m
4 1km
5 10km
6 100km
7 1000km
8 10,000km
9 100,000km (3 1/3 hexes)
9.5 500,999km (16.65 hexes) Auto
10 1 million m (33 1/3) easy
11 10 million m (333 hexes) difficult
12 100 million meters (3,333 hexes) Impossible
12.5 500 million m (16665 hexes) No chance
So now instead of being illuminated by the sun it's hiding behind an asteroid and has been powered off for weeks:
(Vis sig -2.5) (IR sig -2) (Active sig no change)
Our auto points are in the same hex at 7.5 for visible, and 8 for IR, so our no chance point moves to 165 hexes and the impossible level task is at 33 hexes.