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Old September 2nd, 2015, 10:51 PM
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Question Ship Sensor Range???

In Traveller (any version), how far can ship sensors detect (consider the target to be a asteroid or a ship that is running silent)?

I am thinking that Commercial Grade Sensors operate up to 2 light-seconds passively and 3 light-seconds actively, while Military Grade Sensors operate up 3 light-seconds passively and 5 light-seconds actively.

Are there official ranges specified? Are my numbers reasonable? Do you use some other range in your campaign?

I am not looking for any great detail, just a simple rule of thumb. TIA!
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Old September 3rd, 2015, 12:30 AM
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Take a look at the Sensor Rules in my Sig. They're for CT, but I took every piece of info I could find in CT to create the rules.
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Old September 3rd, 2015, 01:01 AM
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In GURPS Traveller.

A Beowulf with a skilled operator, detecting a silent running Beowulf, will do so as follows.

Passive Sensors (with 50/50 chance of detection): 3.5 LS
Passive Sensors (with 100% chance of detection): 0.4 LS

Active Sensors (with 50/50 chance of detection): 35 LS
Active Sensors (with 100% chance of detection): 3.5 LS
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Old September 3rd, 2015, 04:14 AM
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LBB2 (2nd edition, 1981) page 32:
Quote:
DETECTION

Ordinary or commercial starships can detect other ships out to a range of about one-half light-second; about 1,500 millimeters. Military and scout starships have detection ranges out to two light-seconds; 6,000 mm or 6 meters.

Ships which are maintaining complete silence cannot be detected at distances greater than half detection range; ships in orbit around a world and also maintaining complete silence cannot be detected at distances greater than one-eighth detection range. Planetary masses and stars will completely conceal a ship from detection.

Tracking: Once a vessel has been detected, it can be tracked by anyone up to three light-seconds (about 9,000 mm, or 9 meters).
Note that the "millimeters" is for movement charting on a table, with the following scale being used (as noted on page 26):
1:100,000,000
1 millimeter equals 100 kilometers actual distance,
three meters (3,000 mm) equals one light-second
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Old September 3rd, 2015, 10:49 AM
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This is exactly the information I was hoping for.

Thanks to all that replied.
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Old September 3rd, 2015, 11:11 AM
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T5: sensors of any quality can tell you there's "something" out there, more or less regardless of distance.

Full data, including a firing solution, however, is typically only attainable at attack ranges, or (for better sensors) several combat rounds beyond that.
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Old September 3rd, 2015, 01:12 PM
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(based on ct) I just say that 1) computers are part of the bridge, and that ct computers are now the sensor suite, 2) that any sensor can tell if anything is in-system, though perhaps not necessarily what, and 3) ID and targeting range is 1ls per sensor factor, i.e. maximum targeting range is 9ls, modified by gunnery and navigation skills.
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Old September 3rd, 2015, 03:04 PM
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For Mongoose they have a table that shows the ranges and what level of detail each type of sensor (Visual, Thermal, EM, Active Radar/Lidar, Passive Radar/Lidar, NAS, Densitometer) provides at that range. The range bands are
  • Adjacent: <1km
  • Close: 1-10km
  • Short: 10 - 1250km
  • Medium: 1250 - 10,000km
  • Long: 10,000 - 25,000km
  • Very Long: 25,000 - 50,000km
  • Distant: 50,000km +

And whether the sensors can provide Full, Limited, or Minimal data at that each range along with a description of the typical things each type of sensor would show for each level of detail.
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Old September 5th, 2015, 06:02 AM
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I stick with the CT definitions for ranges for now, I have an IMTU matrice of passive vs. active vs. stealth (involves entirely powered down) emissions vs. detection for skill rolls.

So stealthed ships might pass each other at 25,000 km entirely unnoticed, stealth might pick up active better then active picks up stealth, but active picks up stealth better then passive, etc.

In a fleet situation beyond say 5 ships, the assumption is there are so many eyes and skills being applied that beyond very special circumstances detection is largely automatic. Once detected, the 3 LS rule applies.

Then to get more info like type, weapons/engineering status, etc. you scan, to achieve target state to allow unmodified fire you lock on, same roll matrice but with countermeasures applying (the sandcaster options in my Fleet article plus deflectors).

Thus a ship may readily be detected, but not locked onto (but firing weapons or engaging M-drive is an active emission so it's a very limiting strategy to employ).
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