Detection systems

[Lagrange]

Reading through the advanced sensor rules it seems that:
(a) only military large craft can detect emergence waves.
(b) only large craft can detect drive plumes.
which are the longest range and second longest range detection modalities. 

This leads to the rather counter-intuitive conclusion that the best way to detect intruders coming in-system is with small 200 ton military dropships rather than satellites.  I looked through errata to see if there are any updates but didn't see anything.  Am I missing something?

[Daryk]

I suppose it depends on what you mean by "best".  A 2,000 ton Space Station is a Large Craft, and at least doesn't have the outrageous multiplier DropShips do...

[Lagrange]

I suppose it depends on what you mean by "best".  A 2,000 ton Space Station is a Large Craft, and at least doesn't have the outrageous multiplier DropShips do...

Thanks---the price is lower. 

There's a complexification here around automation.  The space station has a much larger crew (46) than the dropship (5).  Ideally, all monitoring systems are either fully automated or optionally manned given the nature of the mission, and that becomes much more important if you have a crew of 46.  Once you install as SRCS it looks the space station ends up half the price of the 200 ton dropship.   Still a win, but not by as much as you may hope.

I'm still rather surprised that satellites are virtually useless for detection and monitoring within a stellar system. 

[Daryk]

I'm sure we could work up some fan rules for very large baseline systems involving a network of satellites, but that's not for this sub-forum.

[Maingunnery]

I'm still rather surprised that satellites are virtually useless for detection and monitoring within a stellar system.

I can kind of see it, most IRL observation satellites only have a single telescope with a terrible narrow field-of-view.


edit: spelling

[AlphaMirage]

It says 'Any' not 'Only.'

In the beginning of the chapter it talks about detection rolls being control checks based on how much comm gear is in a vessel. Satellites and Small Craft equipped with Active Probes and extra comm gear can make a detection check. They just need to mount the right equipment but are not automatically presumed to possess it.

[Daryk]

That's a good point...  Beyond Active Probes (or gear that can simulate them, like EW Equipment), the rules are pretty vague.  I think making the necessary assumptions will get us into fan rules, though.

[Lagrange]

It says 'Any' not 'Only.'

In the beginning of the chapter it talks about detection rolls being control checks based on how much comm gear is in a vessel. Satellites and Small Craft equipped with Active Probes and extra comm gear can make a detection check. They just need to right equipment and are not automatically presumed to possess it.

I'd love this to be true, but if you read the rules this way there's nothing stopping a mech with a beagle probe from functioning as a deep space sensor.   

I believe you need to read the rules as default-no for any action with specific allowed exceptions creating a yes or it becomes quite confusing.  Thus, nothing can do an EM Wave check except a military large craft according to the rules as written (would love to hear a convincing argument otherwise).  For this particular argument, the preface to the section discusses equipment which modifies checks but modifying checks is not generally the same thing as having the appropriate core equipment, just as a targeting computer doesn't cause laser damage.

[Daryk]

The way probes interact with Large Craft ECM supports his case, but you have a point.  Like I said, I think this discussion really belongs in fan rules.

[AlphaMirage]

Thanks---the price is lower. 

There's a complexification here around automation.  The space station has a much larger crew (46) than the dropship (5).  Ideally, all monitoring systems are either fully automated or optionally manned given the nature of the mission, and that becomes much more important if you have a crew of 46.  Once you install as SRCS it looks the space station ends up half the price of the 200 ton dropship.   Still a win, but not by as much as you may hope.

I'm still rather surprised that satellites are virtually useless for detection and monitoring within a stellar system.

Technically the term 'Large Craft' refers to anything Aerospace over 200 tons (according to Total Warfare) so you could have a superheavy system security satellite (like the Caisson) that can be automated and equipped with satellite imagers (if you don't have an NCSS handy). Otherwise I think satellites count as 'small craft' and thus can do the other things that small craft can explicitly do (RADAR/OPTICAL/THERMAL scans or if you'd lucky pick up an IR jump signature).

[Daryk]

Satellite imagers have 30 hex space map range... have to be careful using them...

[Lagrange]

Technically the term 'Large Craft' refers to anything Aerospace over 200 tons (according to Total Warfare) so you could have a superheavy system security satellite (like the Caisson) that can be automated and equipped with satellite imagers (if you don't have an NCSS handy). Otherwise I think satellites count as 'small craft' and thus can do the other things that small craft can explicitly do (RADAR/OPTICAL/THERMAL scans or if you'd lucky pick up an IR jump signature).

Hmm, satellites only go up to 200 tons with the Cassion hitting that.  But apparently airships can be large craft.   Can an airship be a military large craft?

[Daryk]

Maybe, but as I recall, atmosphere hexes count extra for range determination.

[Lagrange]

Maybe, but as I recall, atmosphere hexes count extra for range determination.

When the unit of measurement is AUs, conceding a few hundred kilometers seems entirely reasonable.

[Liam's Ghost]

Hmm, satellites only go up to 200 tons with the Cassion hitting that.  But apparently airships can be large craft.   Can an airship be a military large craft?

There was an errata at some point which raised the maximum mass of satellite support vehicles to 300 tons.

[Lagrange]

There was an errata at some point which raised the maximum mass of satellite support vehicles to 300 tons.

Found it.  And now, satellites can be Large Craft as well.

Is there any clear evidence about whether or not they can be "military"?  It's a design option for dropships, but is there a general definition that forbids or allows it for a satellite?

[Liam's Ghost]

Found it.  And now, satellites can be Large Craft as well.

Is there any clear evidence about whether or not they can be "military"?  It's a design option for dropships, but is there a general definition that forbids or allows it for a satellite?

As far as I know there is no general definition for most types of spacecraft aside from "specifically designed for a military role". Aside from the design option for dropships, I don't think it's ever been codified beyond that. 

[idea weenie]

There was an errata at some point which raised the maximum mass of satellite support vehicles to 300 tons.

And yet we still can't make anything that goes into space massing 301 tons to 1999 tons that isn't a Dropship or really small Jumpship/Warship.

Wish satellite and space station rules could be modified/merged so there was a continuous mass range from .1 tons to 2.5 MTons.  I have ideas on this, but not here.

[Lagrange]

I made some designs here.  It looks like you can save an order of magnitude over other approaches using this thread.

[theagent]

Reading through the advanced sensor rules it seems that:
(a) only military large craft can detect emergence waves.
(b) only large craft can detect drive plumes.
which are the longest range and second longest range detection modalities. 

This leads to the rather counter-intuitive conclusion that the best way to detect intruders coming in-system is with small 200 ton military dropships rather than satellites.  I looked through errata to see if there are any updates but didn't see anything.  Am I missing something?

Well, it depends on what you're trying to detect.

The emergence wave requires the use of "military Large Craft" -- & the question is what size of Satellites that includes (which, per p. 175 of the original SO, are considered "Large Craft", but a "medium satellite" is anything from 5-100 tons, with "large" satellites going up to 200 tons), but whether a satellite is "military" or "civilian" might be up to a GM.

Now, remember, though, the emergence wave detection range might be measured in AUs, but the time to detect it is still limited by the speed of light (8 minutes per AU).  And detection is based on the Pilot skill of the crew, with a +2 modifier, and additional modifiers based on the distance (+ distance in AUs/2) and the strength of the K-F Drive field (- (KF Drive Integrity + DropShips carried, use 1 if no DropShips carried) / 10), rounding any fractions up.  So even a Green crew (Piloting 5) could detect a McKenna out to 17 AUs with a full DropShip load, it's going to be very difficult (17 AUs / 2 = +8.5 mod; 37 KF Integrity + 6 DS = 43, 43/10 = -4.3 mod; 5 + 2 + 8.5 - 4.3 = 11.2, round up to 12), but even a fully Elite (Piloting 0) crew could only theoretically see it out to 27 AUs.  For best results, you want a 7+ for Detection, which means for a McKenna the Green crew can detect it roughly 50% of the time out to 8 AUs (8 AUs / 2 = +4 mod; -4.3 mod for KF field; 5 + 2 + 4 - 4.3 = 6.7, round up to 7), with the Elite/0 crew able to detect out to 18 AUs.  A Fredasa Corvette, however, is going to be much harder to detect, with the KF drive modifier being only -0.6 (KF Drive Integrity 5, 1 DS max), limiting those earlier detection ranges for the Green/5 crew to 11 AUs max, 2 AUs for 50% detection, & the Elite/0 crew only extending those to 21 & 12 AUs.  And those pesky Bug-Eye spy ships shave an AU off those ranges.  In fact, with the smaller ships, there's a chance you may not even detect the emergence wave; a Bug-Eye could literally be 200,000km away from a Green/5 crew, & on a 6 or less they miss the emergence wave; an Elite/0 crew could be 1 AU away & theoretically miss it if they roll a 2.  Note that at some of those ranges, it could take 2 or even 3 hours to even detect the jump.

Which is why, if you're bringing major troop carriers in, you want to jump as far out as possible.  Potemkins have a KF field modifier of -5.4, Leviathan IIIs a mod of -6.6.

Of course, the heat signature from a jump is much easier to spot...provided you're within 50,000km (although technically since the penalty is only +1 per 10,000km of distance I suppose it's possible to catch it from farther out...but even an Elite/0 team is going to be limited to maybe 120,000km max).  The only good news is that, instead of the instantaneous pulse, the heat signature could last for a very long time (jump in LY/2 x # of DS, use 1 if none carried, measured in seconds, then x3).  That McKenna would be visible for up to 270 seconds (depending on the length of jump), but a Bug-Eye would be limited to maybe 45 seconds.

[Lagrange]

Well, it depends on what you're trying to detect.

a) There's a hard limit at 15AU.
b) Large Craft are Aerospace units >200 tons
c) Satellites are errataed to go up to 300 tons.
d) Detection checks for unmanned craft are 7 - Communications equipment /2 so you can hit base 0, surprisingly.
e) I summarized the above in designs here.

[glitterboy2098]

Iirc we know that ground stations for detecting incoming ships exists, because it was a plot point in Test of Vengeance that someone had sabotaged the sensor stations in the planet's detection array, letting an invasion force get in close without detection.

[theagent]

a) There's a hard limit at 15AU.
b) Large Craft are Aerospace units >200 tons
c) Satellites are errataed to go up to 300 tons.
d) Detection checks for unmanned craft are 7 - Communications equipment /2 so you can hit base 0, surprisingly.
e) I summarized the above in designs here.

Did I miss the hard limit for the emergence wave?  If so, that's why you want a good crew manning the mobile platform.

Large might be greater than 200 tons, but there are also civilian craft that are above that size.  Unless the errata changed that, I don't think civilian craft get the systems to detect an emergence wave, even if they happen to be 2 million tons in size.

By chance, do you have the reference about unmanned craft using comm equipment?  I swear I'd read that somewhere, but I've not been able to track it down, so I've hesitated to rely on it too much.

And I love those designs of yours -- you were thinking along the same lines I was.  And let's be honest:  at those prices, you're talking about the cost of a light BattleMech per satellite, so I'd be putting an entire constellation of them up (maybe another 6 or so in a globe based on the zenith & nadir points) just to expand the detection range.

[Lagrange]

Did I miss the hard limit for the emergence wave?

SO page 118 is where I see it.

Large might be greater than 200 tons, but there are also civilian craft that are above that size.  Unless the errata changed that, I don't think civilian craft get the systems to detect an emergence wave, even if they happen to be 2 million tons in size.

Agreed.  I think it's just a question of whether the designer has access to military tech or not.

By chance, do you have the reference about unmanned craft using comm equipment? 

Here between page 10 and 11.

And I love those designs of yours -- you were thinking along the same lines I was.  And let's be honest:  at those prices, you're talking about the cost of a light BattleMech per satellite, so I'd be putting an entire constellation of them up (maybe another 6 or so in a globe based on the zenith & nadir points) just to expand the detection range.

Thanks!  It was much cheaper than I realized when I started this thread.

[theagent]

SO page 118 is where I see it.Agreed.  I think it's just a question of whether the designer has access to military tech or not.Here between page 10 and 11.Thanks!  It was much cheaper than I realized when I started this thread.

Thanks, I did miss that hard max on emergence wave detection range.

I'll have to check, but you included the free ton of comm equipment that satellites are assumed to have in your designs, right?

Also, I wonder...if it would be possible to put more comm equipment into a satellite, I wonder if it might be better to put the satellites past the zenith & nadir points...say, maybe 6 AU past it?  That only adds a +5 penalty to the Detection Check (+2 base, 6 AU / 2 = another +3 penalty)...but then your detection bubble would extend out to effectively 20 AU beyond the nadir/zenith...& you could space out the satellites so that they're all within either 4 AUs or 6 AUs of each other, so that they would be overlapping in their coverage? 

[Lagrange]

Incidentally TO refers to a "military satellite" on page 195, confirming that military satellites are a thing.

I'll have to check, but you included the free ton of comm equipment that satellites are assumed to have in your designs, right?

No.  Where is that stated?

Also, I wonder...if it would be possible to put more comm equipment into a satellite, I wonder if it might be better to put the satellites past the zenith & nadir points...say, maybe 6 AU past it?  That only adds a +5 penalty to the Detection Check (+2 base, 6 AU / 2 = another +3 penalty)...but then your detection bubble would extend out to effectively 20 AU beyond the nadir/zenith...& you could space out the satellites so that they're all within either 4 AUs or 6 AUs of each other, so that they would be overlapping in their coverage?

I believe 15 tons is the maximum communications equipment for any unit?  So 14 is the maximum useful tonnage on a satellite.

Extending detection ranges seems reasonable to me.  Since KF drives have some integrity, you'll typically have a bonus to detection checks as well.  Sphere packing suggests something like 1 satellite at 1 AU holding station out of the ecliptic, 6 orbiting in the ecliptic beyond the jump limit, and 3 more near expending fuel to stay on station around each pole for a total of 13 satellites.  Or if you want a fuel-free solution, you would use 2 near the star and 3 orbits with 6 satellites each far from the star for a total of 20 satellites.  You might also add a few of the airship designs since they are cheap and more difficult to accomplish a drive-by shooting on.

[theagent]

Incidentally TO refers to a "military satellite" on page 195, confirming that military satellites are a thing.
No.  Where is that stated?

Total Warfare (4th Edition, at least that's the PDF I have), p. 212.  Has a list of which vehicle types have "free" equivalents to Comm Equipment:

• BattleMechs, ProtoMechs, CF, ASF, & Combat Vehicles:  1 ton (considered part of the Cockpit/Controls)
• Small Craft & DropShips:  3 tons
• Satellites:  1 ton
• JumpShips:  4 tons
• WarShips & Space Stations:  5 tons
• IndustrialMechs and all other Support Vehicles:  0 tons

The "free" equivalent equipment takes up no extra slots & is counted towards the total of Comm Equipment.  The example on p. 10 of the errata has an example of that:

• Unmanned DropShip has 3 free tons equivalent of Comm Equipment, so its base Detection Check gets an adjustment of -1 (3 / 2 = 1.5, rounded down to 1), for a base of 6.
• Had the DropShip added 3 tons of Comm Equipment on its Record Sheet, the adjustment would increase to -3 (6 / 2 = 3), for a base of 4.

I believe 15 tons is the maximum communications equipment for any unit?  So 14 is the maximum useful tonnage on a satellite.

Extending detection ranges seems reasonable to me.  Since KF drives have some integrity, you'll typically have a bonus to detection checks as well.  Sphere packing suggests something like 1 satellite at 1 AU holding station out of the ecliptic, 6 orbiting in the ecliptic beyond the jump limit, and 3 more near expending fuel to stay on station around each pole for a total of 13 satellites.  Or if you want a fuel-free solution, you would use 2 near the star and 3 orbits with 6 satellites each far from the star for a total of 20 satellites.  You might also add a few of the airship designs since they are cheap and more difficult to accomplish a drive-by shooting on.

I like that.  Probably would be tweaked slightly depending on the star system, of course, but definitely provides some good coverage.  Sol System, for example, based on the charts in SO on p. 86, show the "Proximity Point" shell is 1.52 billion KM out, which is slightly more than 10 AUs (10.133333, to be more precise); the Zenith/Nadir jump points are given as "days of travel", assuming 1G acceleration & turnover at mid-point, although my calculations (x = (at²/2) are coming up with those points being at 10.148 AUs.  Still, if Sol System is essentially looking at a "only Pirate Points can be used within 10 AUs of the Sun" situation, then you could have the outer shell out at, say, 14 AUs (only a +2 mod to pick up anyone Jumping to the Zenith or Nadir points), with most of the outer shell still able to pick up anyone jumping within 1 AU of the Sun (i.e. Earth orbit) with a +7 mod...& then like you said, park a couple near the Sun & you can cover even any pirate points within 2 AUs of the Sun with maybe a +1 or +2 mod at max.

[Lagrange]

Total Warfare

TechManual, I expect---found it in the errata here on page 17.

I updated the satellite design--this shaves a bit off the price.  Thanks :-)

...

If latency is a concern (i.e. in an invasion scenarios), then it may be valuable to park a satellite in an orbit perpendicular to the sun-object axis around objects generating L1 jump points.   Then, detection is effectively instantaneous and absolutely sure.   Otherwise, you pay 8.3 minutes/AU to detect and then if the satellite detecting is far from the place where any response can be generated, another 8.3 minutes/AU to signal the detection.

[ANS Kamas P81]

An orbit is circular around the star, anything placed at the zenith or nadir points without being in an orbit is going to fall due to the star's gravity.  It doesn't just hang there like a lamp.

[Lagrange]

An orbit is circular around the star, anything placed at the zenith or nadir points without being in an orbit is going to fall due to the star's gravity.  It doesn't just hang there like a lamp.

That's why it has 70 years worth of fuel.  Gas it up, and then your grandkid can refill it.