Sensors

[Shadowdancer]

Maybe I'm just dense, but could someone explain to me how starship sensors work in T-20? I'm confused by the book.

Under the skill T/sensors description on pp. 97-98, and the chart on p. 98, it seems to give one set of ranges for each sensor model number.

Then, on pp. 144-146, and the chart on p. 147, it seems to give another set of ranges for each sensor model number.

For example, for a model 5 sensor, the chart on p. 98 says it can detect another ship at X4, or extreme range 4. The chart on p. 147 says Extreme Range 4 is beyond 9,600,000km.

But the chart on p. 147 also says a model 5 sensor can detect a ship at up to 240,000km. That's a big difference.

Also, the p. 147 chart has one column for detection, and another column for encounter distance. Which do you use? In the encounter distance description on p. 144, it says the encounter distance is when the vessels make T/Sensor checks to see if they are aware of each other. Yet the T/Sensor skill description makes it sound like you can do a sensor check at a much greater distance.

And Model 7, 8 and 9 sensor all have detection ranges in excess of 4,000,000km, yet all have an encounter distance listed of 300,000km.

I'm just confused as to when one ship can detect another, and when is an encounter between two ships supposed to begin? When one detects the other? When they reach the encounter distance? When they both detect each other (this would eliminate surprise)? It seems a ship's sensors can detect another ship long before an encounter takes place.

 

[Shadowdancer]

So I'm assuming no one knows how the sensors work?

 

[themink]

Quick reply -

If an expert sits on the bridge in the sensor seat and looks arround with a detailed scan - they use the table in the skills.

If ship is diddly bopping allong and another ship wanders towards it, the encounter range will be based on the table on p147.

If the ship is military and has four crew members on sensor suty (ie two shifts doing watch about) and at reasonably high alert levels then they will be doing regular scans - so the encounter range will end up being based on p98.

I'm not sure I understand what the clash is. The table on p98 is the equivalent on "maximum visual range" and the one on p147 is "likely encounter range".

Since a full sensor scan takes significant time, makes the ship much easier to identify and takes significant power. I imagine civy ships would only do them when emerging from jump space (if then)

I can see a far trader with extra crew doing continual scans - and the pirates getting allert because of all the "spray".

 

[Smiling DM]

I too am having difficulties with the Sensors rules. In the description of the T/Sensors skill, it says a skill check for detecting a ship is DC 10. However in the Combat rules, it says that the skill check to detect a ship starts at DC20. Which is right?

My inclination is to go with the combat rules, as it makes more sense given the size of the range bands (if I interperet the disperate sensor range tables and guess what the range band should be) and assume that the ranges given for various tasks is indeed the true upper limit (which is only 3-4 range bands).

Any clarification would be helpful - it was rather embaressing in front of my players last night when they upgraded to a Model 4 sensor and I couldn't tell them clearly what they had gained in terms of capability.

 

[djpapasmurf]

I think you are getting confused because of the "basic range" categories on page 147.

Ship Detection / Sensor Model 5

Page 98 : Range for detection is X4.

Page 154 : Range of X4 is up to 480,000km.
(each range level beyond X4 is -2 penalty)

Page 147 : Sensor Model/5 has "Detection" up to 240,000km. Also has "Basic" range up to VL, which on page 154 is 240,000km (matching the detection range).

Page 97 : "The sensor operation can attempt to detect any ships or other objects within the range of her sensor systems"

Thus, I would read it as MAX RANGE is X4 or 480,000. Basic range is VL per Page 147 and thus 240,000. So I would say that you can detect up to 240,000 without penalty for range and anywhere between 240,000 and 480,000 would incur the -2 penalties per chart on page 154.

Hope that helps, not sure if I am on the right track either and the differences between the charts is indeed confusing.

SuperStar DJ Papa Smurf

 

[Smiling DM]

Originally posted by djpapasmurf:
I think you are getting confused because of the "basic range" categories on page 147.

Ship Detection / Sensor Model 5

Page 98 : Range for detection is X4.

Page 154 : Range of X4 is up to 480,000km.
(each range level beyond X4 is -2 penalty)

Page 147 : Sensor Model/5 has "Detection" up to 240,000km. Also has "Basic" range up to VL, which on page 154 is 240,000km (matching the detection range).

Page 97 : "The sensor operation can attempt to detect any ships or other objects within the range of her sensor systems"

Thus, I would read it as MAX RANGE is X4 or 480,000. Basic range is VL per Page 147 and thus 240,000. So I would say that you can detect up to 240,000 without penalty for range and anywhere between 240,000 and 480,000 would incur the -2 penalties per chart on page 154.

Hope that helps, not sure if I am on the right track either and the differences between the charts is indeed confusing.

SuperStar DJ Papa Smurf

I follow your example - pretty much got the same results myself in terms of maximum sensor range and basic range band size. I don't like that there is only two range bands possible with the sensors - just doesn't make sense, especially as compared to RL (I work with Navy active SONAR, and I guarantee you that there are more than just two 'range bands' associated with detection probability).

If the range band size is indeed accurate that there are only two bands, then the worst T/Sensor test is only -2 when trying to detect something at the most extreem range capable of a Sensor package - again just doesn't seem right.

Let's say it is - then I am definitely using the DC 20 for basic tests - otherwise there is no need for extensive T/Sensor skill ranks. I mean, if the base DC is 10, then it is only DC 12 to see something just within absolute Sensor range - hell, take your time (and 'Take 10'), and all you need is 1 rank and you can see someone out there (because you will have to be using at least a Model 1 Sensor suite which adds another +1 to your check.

An example from one of the gear-head starship designers would be helpful.

 

[Smiling DM]

Originally posted by Smiling DM:
An example from one of the gear-head starship designers would be helpful.[/QB]

Well, no one seems to have a clear answer. So here is what I plan to use as revised rules. Please poke holes in it, if you find any.

I intend to use the base DC of 10 for T/Sensor detection task, per the description of the skill.

Change #1
Cut the range band of the individual sensor systems by a factor of 5. Thus, to operate at 5 range bands (which would be equivalent to the original base range of a system), the DC would be 18 (fairly close to the combat example). Anything beyond that, gets progressively harder - something out at 10 range bands (the extreme range of the system typically) has a DC of 28, which seems 'right' in terms of real life.

Also, as the ranges between two vessels close (which could take hours or even days depending on range, position, and orignal vestors), this provides a more gradual 'unveiling' of the target.

Change #2
Change the base DC's for the other sensor tasks by a cumulative +2 as you go down the list (I'm at work, don't have my book - intent is the first task below detection is at DC12, the next 14, etc.)

Each of these tests represents a greater level of detail from the target, possibly requiring the use of different filters and processing algorythims to understand the returns, thus each is more technically challenging to the operator.

Change #3
Eliminate the range limitations for T/Sensors tasks.

SO why these changes? From RL experience, I think a Sensors check should only be limited by the equipment and skill of the operator. The range of the target should make the test more difficult, but should not set fundamental limitations as to what can be achieved.

The current method 'double-dips' on the equipment side by allowing higher Model sesnors to work at farther ranges (which eliminates range penalties of -2's) AND adds directly to the test result (each increment adding +1 to the test). This makes the technology a much larger factor in resolving the task - ala 'Star Trek' ("Computer, please analyze the available data and tell me what the solution is so I don't have to think for myself.")

If that's the style of game you want to play, then stick with the original rules.

Personally, IMTU, I prefer the characters to have more of an impact on the potential success of an action - I think my changes fit that approach.

Comments???

 

[Mythmere]

I'd like to bump this thread, because I just ran into the issue myself, and it still confuses me. I take it that at Mod9, any sensor roll in a system beyond 9,600,000 km will be at -2? Because a system with 9 orbits (that is, not a huge one) will have a radius of 5800 million km. Which means that starships are basically completely invisible at any reasonable distance from the mainworld except to a Mod9 sensor.

I don't recall it worked like that in CT, though I could be wrong.