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I'd like to pull sensors out of the combat paradigm thread and deal with them independently so as not to muddy the waters too badly.

Sigg's original sensors are here and Robject's summary version is here.
This is my two bits.
These sensor rules were a set I designed some time ago and have yet to be extensively tested. They were designed for Book 2/Mayday and draw heavily from Star Cruiser and Brilliant Lances for inspiration and mechanics. They need work, so any suggestions would be appreciated.

Sensors come in two types; active and passive, and two classes; civilian and military. Civilian sensors are standard with the purchase of a bridge. Military sensors double the price of a bridge. They require no additional hull volume. Separate rules cover missile sensors and sensor drones.

Sensor Types
Each type of sensor has an auto-spot rating. This is the range at which a given target will be automatically detected.
For active military sensors, the auto-spot range is equal to the tech level in hexes.
For Active civilian sensors, the auto-spot range is equal to tech level-3 hexes.
Homing missiles have a range of tech level-4 hexes.
Sensor drones have the same range as civilian sensors.
Passive sensors of all types have one-half the range of actives, rounded up.

Active sensor Mods (cumulative)
The following modifiers are applied to the auto-spot range for active sensors:
Hull size: 5000,+3; 4000,+2; 3000,+1; 2000,0; 1000,-1
Ships less than 1000, -2
Small craft, -3
Missiles/Drones, -4
Computer Rating, +/- difference between seeker and target
Target shielded by planet or in orbit, -4
Jamming, See Jammer rules below

Passive Sensor Mods (cumulative)
Power Plant letter code: A-F,0; G-M,+1; N-T,+2; U-Z,+3
Small craft -1
Drones/missiles -2
Per G burn of target, +1
Target shielded by planet or in orbit, -4
Computer Rating, +/- difference between seeker and target
Jamming, See Jammer rules below
Targets using active sensors are automatically spotted at any range.

Drones and Missiles
Drones are constructed using the missile design rules from Mayday. They may have one sensor system installed in lieu of a warhead. Drones may also carry jammers which use the jamming rules below. Any drone system costs 5000Cr.Drones have a limited life. Sensor drones function for 4 turns and jammer drones function for 2 turns.
Homing missiles may use either active or passive sensors. There is no additional charge as the sensor cost is included in the guidance system

All ships mounting military sensors and some drones may jam enemy sensors. A jammer is automatically spotted at any range. Sensors attempting to spot through jamming are reduced as follows: if the direct line of sight passes through the jamming hex, -6. If through an adjacent hex, -4. If through a hex 2 hexes away, -2. These are not cumulative with each other, only the highest deduction can be used.

Any target that is within the modified auto-spot range can be engaged. There is no lock-on procedure. Military ships can share spotting, civilian ships cannot. There is no procedure to maintain lock. Each target is checked each turn. There is no limit to the number of acquisitions each ship can make. Any and all targets within auto-spot range can be identified. The auto-spot range is calculated for each target individually.

<whew> ;)

edit: afterthoughts and clarifications.
Here is the version I've used for CT in the past.

Assume military sensors are TL15, model 9, while civilian sensors are TL8, model 1. Add the two numbers together.
8+1=9 which = range of 0.5 light seconds
15+9=24 which = range of 2.0 light seconds

Therefore add 0.1 light seconds range per TL above 8 or per model above 1.

Sensor model is equal to computer model.

The ranges above are for active scans. Passive scans have a quarter of the above range.

Ships have a passive (radiated) signature equal to half of the power plant number (round down) or the maneuver rating used during that turn. Planetoid hulls reduce the radiated signature due to the power plant by 1; buffered planetoids reduce it by 2. This reduction is not applied to the signature due to maneuvering.

The ship's passive signature is multiplied by 0.25 light seconds and subtracted from its range to decide if it is within the sensor range of a scanning vessel.
e.g. a ship with a passive signature of +3 is detected if it moves to within 1.25 light seconds of a ship with military sensors (TL15, model 9).

Ships have a reflected signature based on hull size and configuration USP:
less than 100t, -1
100t-999t, +0
1000t+, +1
5000t+, +2
1-3, +0
4-6, +1
7-9, +2
The ship's reflected signature is multiplied by 0.25 light seconds and subtracted from its range to decide if it is within the active sensor range of a scanning vessel.
E.g. a ship with a reflected signature of +1 is detected if it moves to within 2.25 light seconds of a ship with military sensors (TL15, model 9).

Once a ship has been detected it can be tracked out to 3 light seconds, but once it moves beyond the sensor's auto spot range (modified by target signature) then a roll of 8 or more on 2d is required to maintain the target lock.
+ signature for the sensor type
+ gunnery skill (or navigation -1)
- 1 per 0.25 light seconds outside auto spot range.

these rules are based on the Traveller 2300 game Star Cruiser.
If you want to play cat and mouse then I would recommend changing the scale of LBB2 combat to 30cm = 1 light second, it fits better on a table top
1 G maneuver changes vector by 1cm.
laser to hit range modifiers become:
25cm+, -2
50cm+, -5
75cm+, -8
Active sensor jamming
A ship inside the active sensor range of an opponent may try to fool his active scans by running the ECM program. This actually consists of broadcasting false returns etc. using their own active sensor.

The attacking ship has to roll 12+ to obtain a sensor lock.
+ 1 per level of gunnery skill (or navigation -1)
+ targets reflected signature
+/- 1 per relative TL
+/- 1 per relative computer model

If the attacking ship runs its own ECM program in ECCM mode then it gains a bonus of +4 to the roll to obtain a sensor lock.

Sensor Drones
A sensor drone is a specially modified missile with its warhead removed (or downgraded) and an active/passive sensor system installed. It maneuvers the same as a normal missile.
The drone’s sensors have half the range of the equivalent ship mounted sensors, and the drone can only go active a limited number of times depending on TL. The TL also determines the maximum model of sensor that can be installed. If the drone does not use its maneuver drive it may deploy a folding array to increase its sensor range to the same as that of an equivalent ship mounted system.
Number of active scans equals TL/3 round down.
Maximum sensor model equals TL/5 round down.

Sensor Decoy Drones
These are missiles that are modified to exactly mimic the passive and reflective signatures of the launching ship.
Their warhead is removed and replaced with extendable radiator panels and vanes that are designed to radiate the same heat signature and provide the same target profile as the reflected signature of the launching ship.

Once launched the drone(s) and the ship should be replaced with identical counters. Each then maneuvers separately and provides a problem for the attacking ship.
To identify a bogey as a drone or the ship roll 10+ on 2d.
+/- 1 per relative TL
+ 1 per level of gunnery skill (or navigation -1)

Alternatively, just shoot them all ; the decoy can only take one hit.

Area Jammer Drone
this is a missile modified to transmit as much white noise as possible to confuse active sensors. If the line of sight to a target passes within 0.1 light seconds of the drone then the active ship must roll to penetrate ECM as for active jamming, above.
If the target ship is also using ECM jamming then the active ship must make two roles to obtain a target lock.
Hmm, I think your idea for using the power plant letter rather than number is a better way to do it.

For role playing purposes skill rolls need to be included somehow...
Originally posted by Sigg Oddra:
For role playing purposes skill rolls need to be included somehow...
Yes, that would certainly be the case and that, coupled with the simplistic lock-on rules are two of the most glaring weaknesses in my set.
These were intended for small ship, small squadron wargaming rather than role-playing so I didn't give any thought to skills. Possibly using the difference in operator skill level as a modifier?
Your system seems much more mature, I'll certainly be stealing parts of it. :D

edit: One idea that I've been toying with is increasing sensor capability for larger vessels within a given tech level; a battleship would mount a more extensive sensor array than a destroyer, for example. Perhaps tying it to the bridge size? You would be able to upgrade a ship by increasing the bridge size so as to produce specialized EW vessels.
Piper, tying sensors to bridge size might be a very good way to rate sensor ability. I never thought of that... my solution was to use TL and size code as modifiers.

Tied to bridge size. Very clever...
How about this: 5 tons of a standard bridge is sensors. For each full 10 tons added to bridge size, 5 tons are additional sensors. Ships may voluntarily add additional sensors at a cost of 5 tons/.1MCr per ton. For each additional 5 tons the auto-spot range is increased by 1 hex or 0.25LS (depending on which system you're using).
Ships of 1000 tons require 2 sensor crew. Larger ships, and ships mounting additional sensors require 2 additional crew for each 5 tons of sensors.

Auto-spot range is increased by 1 hex for each 2 levels of sensor ops/navigation skill of the chief sensor operator/navigator (rounded down). For active sensors, a target vessel can decrease its own auto-spot signature in the same way.
For passive signatures, range decrease is based on the skill level of the chief engineer.

I like the CIC idea. Combining the sensor Ops area with fire control would be a good fit.
Your drone missile could only take one hit, but it would be terribly hard to hit. The enemy would think it would be easy, but they would be seeing a bigger target than is really there.
Hmm, interesting divergence. So naturally you see that if you can have better (bigger) bridges for tactical or whatever (snooping etc.) reasons then you should be able to apply it the other way. That is a minimal bridge on even a huge ship that is just about going here to there, like the Nostromo for example.

So how about you simply lump the computer and bridge into one design unit:

  • A factor 1 Bridge costs MCr0.5 and is 20tons. It contains a model/1 electronics suite (1ton), 5 control stations (5tons), 1 ship's locker (1ton), 1 personnel airlock (3tons), and 10tons of slop to use for corridors and common space.</font>
  • A factor 2 Bridge costs MCr1.0 and is 40tons. It contains a model/2 (2tons) electronics suite, 10 control stations (10tons), 2 ship's lockers (2tons), 2 personnel airlocks (6tons), and 20tons of slop to use for corridors and common space.</font>
  • etc.</font>
...or some such.

A hardened bridge rating would replace the old Fib designation and not only provide protection for the electronics but also the crew on the bridge. Not sure what to do about power requirements but for simplicity I'm tempted to just say there are none.

Bridge and computer hits in the old damage system would be the same hit in this (or computer could be external and bridge internal). A hit would reduce the effectiveness of the Bridge model. A hardened bridge would make each hit a half step in reduction.

The whole bridge (electronics, control stations, ship's locker(s), airlock(s) and slop space) is what allows tools, parts, and quick access to identify damage and make emergency repairs. So as the "bridge" is damaged so is your ability to make repairs.

So a 10Kton Ore Processor that is only making a safe run only needs a factor 1 Bridge while a 10Kton Destroyer (which could operate with a factor 1 Bridge) is probably going to have a factor 9 Bridge. And of course in this system there's no reason to limit the Bridge factor to 9 either. And it takes care of your command crewing step in one easy choice if you make the Bridge crew (number of control stations) the only consideration for it.

That's a couple of my thoughts on the related topics.
I like that idea a lot. Suitably scaled, of course. IMTU, 10kt is something you land on rather than fly around in. :D