Megatrav sensor question

[Carlobrand]

MegaTraveller's a bit difficult to interpret sometimes. Apologies in advance for my ignorance.

For small craft (<100 dTons) with small power plants (<1000 Mw) and EM Masking, the guidelines (P89, Ref's Manual) state, "means no emissions". Assuming they don't decide to start blasting in radio or radar, does that mean they can't be detected by passive energy sensors?

Also, when discussing Powering Down as a combat maneuver, the rules (P95, Ref's Manual) direct you to the chapter on Travelling. What chapter on Travelling??

 

[McPerth]

MegaTraveller's a bit difficult to interpret sometimes. Apologies in advance for my ignorance.

For small craft (<100 dTons) with small power plants (<1000 Mw) and EM Masking, the guidelines (P89, Ref's Manual) state, "means no emissions". Assuming they don't decide to start blasting in radio or radar, does that mean they can't be detected by passive energy sensors?

Also, when discussing Powering Down as a combat maneuver, the rules (P95, Ref's Manual) direct you to the chapter on Travelling. What chapter on Travelling??

As I apply them, a ship with so low enegy emission could not be detected by neutrino sensors. If it was on deep space, it could by other pasive sensors (mostly IR). If in orbit of a planet, probably not even so, or at least not so easily.

 

[aramis]

You can detect such "no emissions" targets by reflection, so yes, you can detect them with passives illuminated by the local star.

 

[Carlobrand]

You can detect such "no emissions" targets by reflection, so yes, you can detect them with passives illuminated by the local star.

"(P)assives illuminated by the local star"???

"An EMS Passive Sensor Array combines laser sensor, radar direction finder, radio direction finder, radiation sensor, Passive IR. light amplification, and image enhancement into one integrated and optimized sensor array"

How would that work within the existing rules? There's nothing in the rules about how far out from the local star I am when combat starts, or how much light a given star type's putting out and its relation to sensor function, or my ship's albedo or any of that. Surely I'd expect a difference between, say, my profile from the third planet of a magnitude-A and my profile while approaching a distant gas giant circling a small M-type star. That sounds like we're crafting new rules.

The rules say I drop down an emission class, but then there's no actual description of an emission class less than "under 1000MW", just the statement that there are no emissions. I guess I could invent one, if that's what you're suggesting, just extend it down. However, the logic escapes me: the enemy can't detect the residual heat of my EM Masked 900MW fusion reactor - which, masked, still puts out as much heat as a good-size car engine if I have it figured right - but they can detect the thermal reflection from the magnitude-M star 10 or 20 AU distant?

I'm silent, but I'm not invisible. At high tech, a silent ship is still going to show up on densitometers - they don't have quite the range of the high tech passive EMS array, but they still have excellent range. I'm a headache for the low-tech opponents, but I expect the low tech folk to be using active scanners on expendable scouts and fighters in the first place, because that's the only way the low-techs ever manage a pinpoint roll against even ordinary targets.

 

[aramis]

Carlo, You're ignoring the LI and image enhancement - both rely upon natural light from the local star. We detect asteroids at 2+ AU routinely based upon reflected light alone.

You don't need to invent a new range - the extant "no signature" range already includes stellar effects (as a simplification, it doesn't increase detectability for aspect, position in system, and a dozen other factors that do matter in real life).

No EM sensor works without a source of EMR. Ever. A laser detector only works when a laser hits it. A Radio DF won't work if there's no signal at or above its squelch threshold. Light Amplification still requires light be bounced off the target; it is just that an LI system doesn't include that light, relying on environmental sources.

If you really want to make it matter, Give a +1 signature level for a target in an orbit less than half the hab zone; give a -1 for more than double... But don't stress over it. The sensor rules are convoluted enough as is.

 

[Carlobrand]

I'm not precisely ignoring LI/image-enhancement. Asteroids reflect some light. A civilian ship has no reason to hide and every reason to be seen - it will reflect light. A warship does not want to be seen - to be seen is to be targeted for weapon-fire. A matte-black ship is going to reflect essentially nothing - at least, not in its original wavelength. I don't think it can avoid absorbing that radiation and then re-radiating it as heat. Thus, such a craft is likely to be more visible in infrared than in the visible light spectrum, which is why I focus on thermal reflection - well, re-radiation - rather than light.

That is where I face the paradox in the proposition: the craft's own output of heat, even masked, is higher than anything it could absorb and re-radiate from a distant sun. The idea that the game could describe a masked craft as "emissionless" under such circumstances, but that the craft could be spotted by reflection or re-radiation of stellar emissions, seems to be contradictory.

I don't want to "make it matter." I want to know what the game rules themselves say about this situation. If compelled to "make it matter," I'd extend the existing table down a level and treat it as a -2 DM rather than declaring it "invisible", on the argument that the tables show that masking is not absolute.

 

[aramis]

You can't have a true "Zero reflection" nor a true "zero emission" object with a temperature aboard above 0 Kelvin (-273.3° C).

You're reading way too much into "No Emissions" ... just call it "very low" instead, and ignore it. It's better for gaming, it's better for sanity.

 

[Carlobrand]

"Very low" works for me. Who proof-read these rules, anyway??

 

[aramis]

"Very low" works for me. Who proof-read these rules, anyway??

Don't know, but it sure is an issue. Love the game, hate the editing.

 

[McPerth]

How will you handle a solar powered defense satellite drone, with no neutrino emisions (as it has no fusion plant), deployed in relatively close orbit to a planet (so its IR emisions masked against the planet's own)?

IMHO it should be quite difficult to detect without resorting to active sensor measures (and so being sure you are detected).

 

[BlackBat242]

Also, when discussing Powering Down as a combat maneuver, the rules (P95, Ref's Manual) direct you to the chapter on Travelling. What chapter on Travelling??

Anybody have an answer for this... or is it more poor editing?

 

[BytePro]

How will you handle a solar powered defense satellite drone, with no neutrino emisions (as it has no fusion plant), deployed in relatively close orbit to a planet (so its IR emisions masked against the planet's own)?

IMHO it should be quite difficult to detect without resorting to active sensor measures (and so being sure you are detected).

You didn't define a distance - anything can be hard to detect if far enough away, of course.

In relation to the satellite being of any use - i.e. detecting the intruder - generally it will be readily detectable passively, assuming one is in space past the orbit and with a FOV encompassing the planet. The drone will be moving relative to the surface or will be in geosync (outside atmo or without an atmo to conceal it better) and easily detectable visibly. During part of its orbit it would be concealed, in which case it would only be useful if it had neutrino sensors that could see through the planet (in which case so could the ship).

Being detectable, however, is not the same as to be identified as to purpose. The satellite may be made to appear natural - i.e. a moonlet drawing solar power via disbursed fiber optics - or is 'concealed' to look and act like other satellites whose nature is obvious.

 

[Carlobrand]

By an interesting coincidence, I've been playing a bit with the idea of small sensor-equipped satellites. More on that elsewhere after I've finished. With respect to this, I might point out that the densitometer tends to defeat most camouflage efforts. When you start seeing machinery underneath the asteroid surface, you can probably conclude it's not a normal asteroid.

My own designs so far, drawing on MegaTrav rules, rely exclusively on passive sensing and feed signal via maser link to a rear processing center - a ground base (which is why the maser) or SDB with Model-9 computers (also the reason for the maser: maintains link even when the SDB's hiding in a gas giant's atmosphere). Unmanned and with the computer processing occurring elsewhere, they are exceedingly small - around a half dTon. They operate off small fusion plants generating about a megawatt, they're EM-masked, and they have grav generators and Model-0 computers so they can be piloted remotely within a gravity well: in the event of concerted attack, they can be withdrawn to the planet's surface and landed (or flown into concealment in the gas giant's atmosphere, a piloting skill roll in either case) until the threat is abated. At TL14 to 15, they have a chance (roll of 12 on 2d6) at spotting a dreadnought at 575 thousand kilometers and a fighter or small craft at 475 thousand kilometers. They only cost around MCr1.6 each, so deploying enough to gain multiple chances is not terribly expensive. I figure about 10 in orbit ought to give better than a 5 in 6 chance of spotting a dreadnought at 525 thousand kilometers and a boat at 425.

(I'm debating a more expensive 6g variant that can orbit at 150 thousand kilometers to give better advanced warning while improving defensive agility and preserving the ability to dash for the safety of the planet if attacked.)

On the reverse, it depends on a ruling: craft of under 1000 MW already occupy the lowest detection band for passive energy sensing, but masking is supposed to give them an additional -1 band, and I'd argue that a craft generating 1/1000 of that deserves additional consideration, but it isn't exactly in the rules. Figure them being detected at a maximum range of anything from 475 thousand kilometers to 375 thousand kilometers on passive energy sensors, depending on the ruling.

However, they can not escape the densitometer. If you use the lowest detection band (for craft under 100 tons), then a TL15 warship with equivalent equipment has a chance to spot them (roll of 12 on 2d6) at 375 thousand kilometers just by using the densitometer - a squadron of fighters (or any other warcraft) should have no trouble detecting them at 325 thousand kilometers, and there's really nothing stopping a single missile from scrapping these things at that range.

So, finding an alternative to the fusion plant MIGHT buy you a bit of space, but only a narrow bit.

Bottom line is, they should spot you before you spot them, and if they're in low orbit, they ought to be able to withdraw and land (or hide in a gas giant) before you threaten them. If you leave them up, they die pretty quick.

 

[E.D.Quibell]

Any use?

Cornwell Class Covert Sensor Platform
Ewan Quibell 2009-10-30
Updated 2009-12-20

CraftID: Cornwell Class Covert Sensor Platform, TL9, Cr650,345
Hull: 2/5, Disp=2, Config=9USL, Armour=50,
Unloaded=29.47 tons, Loaded=29.47 tons
Power: 1/2, Batteries=0.96 Mwh, Solar=0.06235 Mw,
Duration=7.6 hours/unlimited
Loco: -
Comm: Radio=System, Laser=System
Sensors: EM Mask, Radar Direction Finder, Radio Direction Finder, Adv Image Enh, Laser Sensor 2nd Gen, Passive IR, Light Amplification,
Off: Hardpoints=1
Def: DefDM=+2
Control: Computer=0/bis, Panel=Computer linked x7
Accom: -
Other: 5 klitres of planetoid tunnelled, Cargo=0.21 klitres, ObjSize=Small,
EmLevel=Faint (None)
Comment: Construction Time=8 weeks single, 6 weeks multiple

The Cornwell Class is an older model covert sensor platform of the old Empire’s design. Cornwells are passive devices deployed in stable orbits to form a network of sensor platforms designed to gather intelligence for the old Imperial Navy. A minimum of 4 Cornwells were deployed in any system in order to triangulate data from their sensors, and the platforms are programmed to coordinate the network between themselves to provide accurate data.
The need for the network is twofold, firstly each platform being static can only provide one heading for radar and radio direction, and secondly because it is not possible to run both the radio (to receive) and the radar direction finder continuously at the same time using just the power form the solar cells. The platform is programmed to run from the solar cells indefinably. The laser communicator is only used for communications between the other members of the network and then only infrequently and draws the power to do this from the batteries, otherwise it is kept powered down. With all the sensors active the total power draw is slightly higher than that provided from the Solar cells, so for around 65% of the time both the radio and the radar direction finder are in use. The resulting 35% of the time is used to recharge the batteries to the 60% charge level. The batteries are charged to 60% capacity and only ever drawn down to 30% capacity in order to extend their useable life indefinitely. This available capacity gives the Laser communicator a 12 hour continuous operational window before the platform has to recharge the batteries. With either the radio or the radar direction finder powered down it takes a little over 24 hours for the solar cells to recharge the batteries from 30% to 60% level.
The sensor network provides it’s intelligence by firstly deciding which nodes will run the radio predominantly and which will run with the radar detection finder predominantly and then performing a sensor baseline of the system. While in baseline mode the network simply receives data and analysis it in order to identify the “normal” objects in system. Once the network has established what it believes to be the baseline of the system it continues to use the data to reaffirm its current baseline image and also uses it to identify abnormalities, or changes to the baseline. It then flags these changes for analysis by the network operator. It can take a significant time to establish an accurate baseline of any system; however it is known that Cornwell sensor networks have worked in systems for decades without the need for any maintenance.

 

[Hyphen]

Anybody have an answer for this... or is it more poor editing?

Poor in that it should have directed you to Travelling in the Player's Manual and these rules:

Step 2 - Power Up

If the ship has been parked for less than 8 days, the power plant may be warm started; otherwise, it must be cold started.

To warm start a starship:
Routine*, Engineering, Edu, 30 sec.

To cold start a starship:
Routine*, Engineering, Edu, 5 min.

 

[Carlobrand]

I found no such entry in the Player's Handbook. I did find it in my Imperial Encyclopedia, oddly enough. Of course, neither 30 seconds nor 5 minutes have much meaning in relation to a 20 minute combat turn, so that leaves certain questions unanswered with respect to space combat.

As to the Cornwell:
A 20-dTon rock is not going to provide any concealment against TL13 or better densitometers - they'll show everything down to the deck-by-deck floor plan. Also, unless it's feeding data to a more effective computer elsewhere, its effective sensor range is too low - a Zhodani destroyer could detect it and destroy it with missile fire from outside the Cornwell's effective sensing range. A TL12 Hi-P densitometer would be able to look inside as well. Might be useful below TL12, though - or perhaps in the anti-piracy roll, given that pirates don't tend to have the best equipment.

 

[McPerth]

I found no such entry in the Player's Handbook. I did find it in my Imperial Encyclopedia, oddly enough.

Yes. it's on IE, page 92

Of course, neither 30 seconds nor 5 minutes have much meaning in relation to a 20 minute combat turn, so that leaves certain questions unanswered with respect to space combat.

You must remember those are time increments, not absolute times (the task is not labeled as absolute). So, you must multiply the task by 3d6 (RM, page 13). Duration is explicited as increment time times 3D /after any DMs are applied. I've not been able to find which are those DMs, but I guess those are your DMs when doing the task (in the case of engaging a PP, they would be Eng+edu).

So, for starting a Power Plant, time will average 5 min (if hot) or 50 min (if cold). Although, remember that if you don't do double checks (cautious task, so doubling time), you risk trouble afterwards (IE page 92 too, on the explanation of the asterisk in the tasks).

 

[Carlobrand]

You must remember those are time increments, not absolute times ... So, you must multiply the task by 3d6 (RM, page 13). Duration is explicited as increment time times 3D /after any DMs are applied. ...

So, for starting a Power Plant, time will average 5 min (if hot) or 50 min (if cold). Although, remember that if you don't do double checks (cautious task, so doubling time), you risk trouble afterwards (IE page 92 too, on the explanation of the asterisk in the tasks).

My admittedly limited ardour for this particular rule system is diminishing rapidly. Reminding me more and more of Star Fleet Battles every day: more time spend figuring out the rules than playing the game.

Referee manual, P.12:
"The Universal Task Profile (UTP) provides players and referees with a simple (but still comprehensive) method of codifying tasks. To set up a UTP for a task, simply answer these questions.
OHow hard is the task?
OWhat skills and characteristics are crucial to the success of this task?
OHOW long does this task typically take?
ODoes this task involve any special risks?"

Referee manual, P.13:
"HOW LONG DOES THIS TASK TAKE?
Estimate how long the task typically takes using whatever time increment is most convenient Approximations are fine. Divide the time estimate by 10 for use in the UTP. A roll of 3D (whose average result is 10) is used to determine how many of these time increments the task actually takes. Remember the UTP time increment is always one-tenth of the total
estimated task duration."

I'm reading this as divide the time estimates (30 seconds, 5 minutes) by ten, and THEN roll 3d6 by the result, so that you AVERAGE the estimate but can come out anywhere from 3/10 the time to 1.8 x the time. Thus, 9 to 54 seconds for the warm startup, 1.5 to 9 minutes for cold startup. Plus the cautious thing. What is a "determination roll"? It appears in this instance my control over my character's behavior is less than total.

 

[McPerth]

Referee manual, P.13:
"HOW LONG DOES THIS TASK TAKE?
Estimate how long the task typically takes using whatever time increment is most convenient Approximations are fine. Divide the time estimate by 10 for use in the UTP. A roll of 3D (whose average result is 10) is used to determine how many of these time increments the task actually takes. Remember the UTP time increment is always one-tenth of the total
estimated task duration."

I'm reading this as divide the time estimates (30 seconds, 5 minutes) by ten, and THEN roll 3d6 by the result, so that you AVERAGE the estimate but can come out anywhere from 3/10 the time to 1.8 x the time. Thus, 9 to 54 seconds for the warm startup, 1.5 to 9 minutes for cold startup.

I don't have my boks with me now, so I'll answer you from memory.

The UTP is deffined as: difficulty, skill, stat, time increment, specials

The time shown in the UTP is the time increment (the UTP time increment you quoted above), and so is this time increment that is multiplied by 3 D (minus DMs).

Plus the cautious thing. What is a "determination roll"? It appears in this instance my control over my character's behavior is less than total.

IIRC determination is defined as a derived characteristic equivalent to Int+End. Is used in various tasks to see if your character is determined enough to finish them, to repeat a failed task, etc.

IIRC the task uses to be difficult.

 

[Carlobrand]

Ah, you're right, Pg 11: "The time increment on a task profile is 10 percent of the typical task duration."

What does it say about a roleplaying game that it gives you a rule for finding out how long it takes to "diagnose damage done to an air/raft"? Lord-almighty! 2 and a half hours later: "Yep, here's yer problem. See, right here, this big fist-size hole right in the middle of it." :rofl: