Stealth with decoys

[Rich.h (OP)]

I had an unpleasant encounter in my current game recently where my nice stealthy recon ship got a little too close and was escorted out of an NPR home system. The event turned out quite well as the NPR in question were not hostile and are now good trading partners. But it did highlight the total vulnerability of my stealth designs, since my doctrine for such ships always leans towards the idea of see without being seen and make a get away rather than fight. I find this method means I don't waste space on things such as big pew pew things that in turn mean needing bigger engines which in turn destroy my TH signature.

So trying to think outside of the box my ship engineers came to me with a possibly radical idea, the use of decoys. The way a decoy is meant to work is that we have very high powered sensor probes that will give out a large EM signature and thus hopefully be of more interest than the recon ships own TH signature. Once a decoy is dropped the recon ship can reduce engine power to a point where it can make a very quiet yet slow maneuver away from the decoy position, with luck if an enemy focuses on the decoy EM output then by the time they arrive in scanning range the recon ship is already well out of range for it's now much reduced TH signature. The possible side advantage of this being the decoys can also be used as standard sensors in space to cover places with an active scanner to save on the cost of a ship being there.

MIL 403 Hermes MK2 class Recon Frigate    20 000 tons     459 Crew     7172.1 BP      TCS 40  TH 211.2  EM 1560
4400 km/s    JR 3-50     Armour 5-65     Shields 52-300     Sensors 360/360/0/0     Damage Control Rating 31     PPV 36.18
Maint Life 0.12 Years     MSP 2224    AFR 3200%    IFR 44.4%    1YR 18463    5YR 276945    Max Repair 1250 MSP
Intended Deployment Time: 18 months    Spare Berths 0   
Troop Capacity: 1 Company    Magazine 463   

Powedll Class 3 Hyperdrive     Max Ship Size 20000 tons    Distance 50k km     Squadron Size 3
Powedll Class 4 Fusion Drive (2)    Power 880    Fuel Use 22.4%    Signature 105.6    Exp 10%
Fuel Capacity 1 300 000 Litres    Range 52.2 billion km   (137 days at full power)
Alterman Theta Shields (13)   Total Fuel Cost  260 Litres per hour  (6 240 per day)

Chambers-Foster Gauss Turret (2x4)    Range 40 000km     TS: 40000 km/s     Power 0-0     RM 4    ROF 5        1 1 1 1 0 0 0 0 0 0
Chambers-Foster Phalanx (1x8)    Range 1000 km     TS: 25000 km/s     ROF 5       Base 50% To Hit
Muravyov Fire Con MR-48 TS-25k (1)    Max Range: 48 000 km   TS: 25000 km/s     79 58 38 17 0 0 0 0 0 0

Chambers-Foster Size 50 Buoy Launcher (1)    Missile Size 50    Rate of Fire 5000
Muravyov Probe Targeting (1)     Range 19.4m km    Resolution 100

Muravyov Search Sensor MR-102m R-10 (1)     GPS 1800     Range 102.5m km    Resolution 10
Muravyov TH Sensor 360 (1)     Sensitivity 360     Detect Sig Strength 1000:  360m km
Muravyov EM Sensor 360 (1)     Sensitivity 360     Detect Sig Strength 1000:  360m km
Cloaking Device: Class cross-section reduced to 10% of normal

ECM 30

This design is classed as a Military Vessel for maintenance purposes

Missile Size: 49.97 MSP  (2.4985 HS)     Warhead: 0    Armour: 0     Manoeuvre Rating: 10
Speed: 0 km/s    Engine Endurance: 0 minutes   Range: 0.0m km
Active Sensor Strength: 47.34   Sensitivity Modifier: 180%
Resolution: 1    Maximum Range vs 50 ton object (or larger): 8 520 000 km

If I am understanding EM sensors correctly then a sensor buoy like this should be spotted by the recon ship at a range of around 17m km or is that wrong? Also note that I am currently playing on a game without overhauls, in addition it is mandatory that all naval vessels are capable of repairing at least twice over the most complex component and are required to carry security personal at all times. This is why the ship has such a large amount of MSP and troop capacity. So has anyone ever tried anything like this before and if so how did it work out?

[Havan_IronOak]

I'm a newbie but I like the idea.

How do you deploy it? Since its a missile with no engine do you just target their home world and fire?

[83athom]

Several ways. 1; Set a waypoint, fire, then delete way point (all in the same increment). 2; Order to "fire missile at" a target.

[Iranon]

EM signature of a sensor scales linearly with resolution, if you mostly want a decoy you can have the same effect with a size-1 buoy.

[Rich.h (OP)]

EM signature of a sensor scales linearly with resolution, if you mostly want a decoy you can have the same effect with a size-1 buoy.

Ok I am a little confused by this, I was under the impression that an EM sensor picks up EM from colonies, shields, and active sensors. This being the case then is it not the actual active sensor strength that generates the EM rather than simply the resolution?

[83athom]

He is saying you can get the same affect with a smaller sensor with a larger resolution. GPS = Size (in hs)* tech lv * resolution. Passive em sensors will detect a higher gps at a longer range.

[bean]

Ok I am a little confused by this, I was under the impression that an EM sensor picks up EM from colonies, shields, and active sensors. This being the case then is it not the actual active sensor strength that generates the EM rather than simply the resolution?

Pretty much.  For reasons that I don't understand, low-res sensors are detectable much further away than equivalent-size high-res ones.  So the best decoy is a Size 1 missile with the lowest resolution (highest detection size). 
Another way to implement this would be to mount the decoy as the second stage of a missile, which is then fired at a waypoint.  That way, the decoy doesn't start broadcasting right on top of you, and you can position it to better distract the bad guys.  (Obviously, this probably won't work with the massive decoy you have here.)
If you want to be really clever, then build a missile that has ship-level speed and decent endurance, with an appropriate sensor.  This can either be fired directly, or used as a second stage, with appropriate settings during building.  (This will be tricky to set up, as you have to measure range to the target waypoint rather precisely to get it to come on when it's supposed to.)

[Rich.h (OP)]

Ok it seems then I have totally misunderstood how EM works to start with, so going back to the board on this one slightly with some basics the wiki states that.

GPS is range * resolution, and after some checking I also found that GPS is what is classed as the signature strength (EM) in the detection formula. So if that is correct then am I right with this example below.

A resolution 10 sensor that has a detection range of lets say 5000km will produce a GPS(EM) of 50,000. If you have an EM detection strength of 10 then this sensor would be detected at 500m km (10*50,000*1000)

If that is correct then taking it a step further with the idea above about having it as a running decoy I came up with this.

Missile Size: 2 MSP  (0.1 HS)     Warhead: 0    Armour: 0     Manoeuvre Rating: 10
Speed: 5000 km/s    Engine Endurance: 72.1 hours   Range: 1 297.0m km
Active Sensor Strength: 1.026   Sensitivity Modifier: 180%
Resolution: 2    Maximum Range vs 100 ton object (or larger): 260 000 km
Cost Per Missile: 1.7666

Am I correct in thinking that with just an EM 11 sensor this missile would appear on scopes from somewhere in the region of 3.9bkm away?

[bean]

No.  A very small size-2 active isn't going to be picked up several AU away by a strength 11 sensor.  I'm not sure exactly how many GPS it will have, but it's going to take a very high resolution to make it detectable at long range.

[83athom]

GPS = Size (in hs)* tech lv * resolution. Passive em sensors will detect a higher gps at a longer range.

[bean]

Exactly.  I worked it out separately, and that's the correct formula. 
So the notional resolution-2 decoy could have a GPS of 2.052, and a detection range (EM 11) of 22,572 km.  Yes, in theory it can detect anything with an EM 11 sensor before it is detected.  This is obviously bad in a decoy.  Now, if we made the sensor resolution 100, it could be picked up by our notional sensor at 1,128,600 km, and would itself have a range of 1,838,477 km.  The detection range is still above the intercept range, but not as much as before.  I can't recall what the resolution cap is.  If it's 500, then you have an EM intercept range of 5,643,000 km and the sensor itself would have a range of 4,110,960 km.  (The intercept range scales linearly with resolution, the active range with the square root of resolution.)
I plan to test decoys in one of my games before too long, to see how the AI behaves around them.

[Rich.h (OP)]

GPS = Size (in hs)* tech lv * resolution. Passive em sensors will detect a higher gps at a longer range.

Can you link to where you found this formula? The wiki glossary states "Gravity Pulse Strength - A measure of the strength of an active sensor. GPS is range * resolution." Unless this is badly written I read that to mean the resolution of the sensor * the range of the sensor? Also what tech level are we talking about, the EM detection tech or active sensor tech? Does that mean a staright 1,2,3,etc for the tech level beyond the TN age, or is that a number as defined by the exact strength given by a tech level for example EM/Active strength 36.

[bean]

Can you link to where you found this formula? The wiki glossary states "Gravity Pulse Strength - A measure of the strength of an active sensor. GPS is range * resolution." Unless this is badly written I read that to mean the resolution of the sensor * the range of the sensor? Also what tech level are we talking about, the EM detection tech or active sensor tech? Does that mean a staright 1,2,3,etc for the tech level beyond the TN age, or is that a number as defined by the exact strength given by a tech level for example EM/Active strength 36.

The wiki is often wrong (or, more accurately, out of date).  Look at a few ships, and you'll see that it's clearly not range*resolution.  I derived the same formula he gave from ships posted on the forum and a bit of math.  (There were pairs of active sensors on some ships where the GPS differed by res1/res2 and the range differed by sqrt(res1)/sqrt(res2).  I assumed similar techs, which meant that the sensors were the same size (and thus the same strength) and the range differences were down entirely to resolution.  Thus, GPS must be proportional to resolution.  There were other cases where two sensors of the same resolution had GPS values which differed as range1/range2, and thus active sensor strength was range1/range2.  Assuming that all sensors involved had similar EM tech, the obvious equation is GPS=sensor strength*resolution.  Yes, I'm an engineer.)
Active sensor tech is the controlling tech here.  EM sensor tech on the part of the person building the sensor just means that he gets more range for a given active sensor strength.  (Actually, this is true even to the point that making a bigger active sensor with low active sensor strength tech provides no benefit in terms of counterdetection probability.)  Active sensor strength is defined as active sensor tech*active sensor size. 

[Rich.h (OP)]

I see so the actual correct formula then is GPS= sensor size (in H.S) * Active sensor tech level * sensor resolution. So my only confusion now is the tech level part, does this refer to a tech "level" as in 1,2,3 etc like ruins provide. Or is it an exact copy of the number given by the Active sensor research project. For example if you have just researched the very first active sensor tech which of the following would give you a correct GPS figure?

1. GPS = size * 10 * resolution
2. GPS = size * 1 * resolution

[bean]

I see so the actual correct formula then is GPS= sensor size (in H.S) * Active sensor tech level * sensor resolution. So my only confusion now is the tech level part, does this refer to a tech "level" as in 1,2,3 etc like ruins provide. Or is it an exact copy of the number given by the Active sensor research project. For example if you have just researched the very first active sensor tech which of the following would give you a correct GPS figure?

1. GPS = size * 10 * resolution
2. GPS = size * 1 * resolution

The exact number given by the research project.  I don't know of any cases where the numerical position of a tech in a tree is used (as opposed to the number on the front of the tech.)