Sensor Systems

Active Sensors:

Active sensors are those detection and ranging systems that operate by illuminating an object, typically with low doses of radiation, and analyzing the energy reflected back to it by those objects.  This provides for the accurate relay of information about the target, but the active signal can be readily detected by any other craft with the requisite passive detectors.

EMAS/LIAS:

The earliest EMAS (Electro-Magnetic Active Sensor) systems were developed and used by the majority of races since before the discovery of space travel, and advanced forms of EMAS are still in use in the modern era.  EMAS works by emitting EM Radiation (radio waves most early versions) out of its main antenna, when this EM radiation comes in contact with an object, particularly ferrous objects; it reflects back to the EMAS.  The returning radiation is then analyzed to determine information about the target, range, speed, size, etc...  Conventional EMAS’ use fixed phased array systems, operate on multiple frequencies and have incredible tracking capabilities. 

An extension of EMAS, LIAS (Laser Illumination Active Sensor) operates in the same way as EMAS but uses lasers instead of EM radiation waves.  High end EMAS/LIAS are also able to take detailed scans of objects that can determine great detail about it so are ideal for short range identification and scanning of the exterior of an object.

EMAS/LIAS have serious limitations however since they are EM radiation based sensors they are limited by the speed of light: 283,268.47 KiloMetra/CentiPulse (KMe/cP) (186,282.4 Mile Per Second (MPS), 299,729.458 Kilometers Per Sec (KPS)) in vacuum.  The practical application of this means, that it takes 161 seconds for a signal pulse to return from a target that is only 15 million miles away.   While this means that an EMAS might have an effective detection range of 15 million miles, the information it receives will be a minute out of date by the time the return is detected.  This limitation makes EMAS ineffective for targeting any craft more then 1 Light Pulse (1 LP = 28.3 GigaMetra (GMe)) from the sending craft (Confed), or 1 Light Minute (11,176,944 Miles/17,983,767 Km)(GF).  For targeting purposes it is even more limited, resulting in an effective targeting range of 1 Light Centipulse (Confed), or 1 Light Second (GF).

EMAS/LIAS is also highly susceptible to jamming and the use of stealth systems.  The interstellar medium is alive with EM radiation, this radiation can diffuse EMAS waves, scattering and sometimes cancelling them out.  Even a low powered jammer can be enough to hide a ship from EMAS if it is in or near a volume of space where there is above background level EM radiation.  As such, EMAS jammers are a common feature on most warships.  The composition of standard hull armor, in particular the nano-sheet outer layers, also makes detecting a ship with EMAS more difficult.  The nano-sheet can absorb the EM radiation that impinges upon it, giving minimal return.  LIAS can be similarly jammed by dazzling the laser sensor either by hiding in front of or near a bright object (star, planet, etc…).  The table (Table 1) below illustrates the ideal ranges for EMAS/LIAS assuming no jamming or outside interference.

Table 1 EMAS Detection Ranges

(These ranges represent an ideal vacuum; atmospheric ranges  decrease by a factor of 1000.)

EMAS Detection Ranges	Small (KMe/LCP)	Medium (KMe/LCP)	Large (KMe/LCP)
Light Strike Craft / Shuttles	500,000 / 1.76	1 million / 3.53	1.5 million / 5.3
Heavy Strike Craft / Bomber	2.5 million / 8.83	5 million / 17.65	7.5 million / 26.48
Civilian Transport	3.75 million / 13.24	7.5 million / 26.48	12.5 million / 44.13
Corvette	7.5 million / 26.48	15 million / 52.95	22.5 million / 79.43
Cruiser	10 million / 35.3	20 million / 70.6	30 million / 105.9
Destroyer	12.5 million / 44.13	25 million / 88.25	37.5 million / 132.38
Battleship / Heavy Carrier	15 million / 52.95	30 million / 105.9	45 million / 158.86
Orbital Installations	25 million / 88.25	50 million / 176.511	75 million / 264.77

TAS:

TAS (Tachyon Active Sensors) works along similar principles to EMAS.  Instead of emitting EM radiation however, they function by first capturing etheric Tachyons, using a standard Tachyon trap.  These captured Tachyon are then then fired out as low powered beams (Tachyons move faster at lower energy states).  Like EMAS, once these tachyon particles strike an object they are reflected back to the source.  The most basic TAS systems are applied to virtually all starships because they share over half of their components with a ship’s Tachyon Communications systems, including the tachyon trap.  However these are simply detection arrays and any TAS used for targeting is far more expensive, making the use of targeting TAS’ rare outside of major superpowers.  The biggest advantage of the TAS is the fact that detection is virtually instantaneous.  Many joke that they receive the pulse before it is even sent.  A secondary advantage is that TAS is all but unjammable due to the specific tuning of TAS signals making stealth fields and materials useless against them.

TAS has its disadvantages too.  For an FTL sensor it has a short effective range, only a factor of ten increase over more contemporary EMAS systems.  This is despite the fact that Tach Comm units are capable of transmitting and receiving communications at light years equivalent distances.  A fighter that can detect another craft at 4 million miles will have an integrated communications array able to talk to that same craft at up to .4 light years. 

This is due to the power requirements of the TAS and the fact that there is a lower power requirement for the level at which tachyons can be detected and trapped.  In theory, a zero energy tachyon would travel infinity fast, but would be almost impossible to detect or trap. 

The second major disadvantage is the fact that the standard detection TAS cannot give any information on a target other then its position, relative size, and velocity (vector) at the time of signal intercept.  Even targeting TAS are not as accurate at target identification at close range to their EMAS counterparts.  The speed and scatter of the intercepted tachyon returns gives very low detail resolution on anything smaller then capital scale TAS receivers. 

The final disadvantage, the one that is the biggest problem for tacticians, is that the TAS reveals itself to any other craft with a tachyon based system once it detects them.  This of even greater concern due to the fact that the inverse square law is also in effect for tachyon beams.  This means that the ship under scan will be able to detect the scanning ship at nearly twice the range that it can be detected.  It is for this reason that the system is primarily used only in combat to gain an accurate position of an enemy that already know you are out there.

Table 2 TAS Detection Ranges

TAS Detection Ranges	Small (KMe/LP)	Medium (KMe/LP)	Large (KMe/LP)
Light Strike Craft / Shuttles	20 million / 0.7	40 million / 1.4	60 million / 2.1
Heavy Strike Craft / Bomber	100 million / 3.5	200 million / 7.1	400 million / 14.1
Civilian Transport	150 million / 5.3	300 million / 10.6	500 million / 17.6
Corvette	300 million / 10.6	600 million / 21.2	900 million / 31.8
Cruiser	400 million / 14.1	800 million / 28.2	1.2 billion / 42.4
Destroyer	500 million / 17.6	1 billion / 35.3	1.5 billion / 52.9
Battleship / Heavy Carrier	600 million / 21.2	1.2 billion / 42.4	1.8 billion / 63.5
Orbital Installations	1 billion / 35.3	2 billion / 70.6	3 billion / 105.9

Active system Disadvantages:

All active scanning systems have one inherent disadvantage, the inverse square law.  Simply stated, the radiation emitted by these sensors can be detected at twice the distance it is sent from.  This weakness allows for an enemy with a passive detector to notice the scanning hostile long before it sees them.  Beyond extreme detection ranges, the craft under scan can see EMAS/LIAS/TAS particles sent out long before it is seen by them.  The common solution to this is to “ping” the sensors, sending out only short, but highly intense, radiation pulses instead of continuous illumination.  Clever crews will only ping once or twice at specific wavelengths and frequencies before moving to a new position and sending out another set of pings, this makes determining a ship’s exact location much more difficult.

Passive Detectors:

Every ship, be it online or shut down, emanates radiation.  This can be minimal or massive amounts that fill the EM spectrum.  Even so called black ships, that no EM radiation when coasting, will produce radiation all along the EM spectrum as soon as they power up or activate their drive systems.  To this end all one need to do to detect any incoming ship is possess passive detectors that will detect these emanations.  Not all the radiation an active ship generates is in the electromagnetic spectrum, but also beyond it to subatomic particles that cannot be stopped by any physical matter and Faster Then Light Graviton waves.  Passive sensors generally operate in two modes:  scanning, by which the passive array looks at specific parts of the sky to detect craft at long range, and true passive, when it simply intercepts and interprets any radiation bathing it.

Electromagnetic Detection Equipment:

All starships have built in sensors with the ability to detect the radiation that pours on them at all times in space.  This data is then analyzed to determine whether it is background noise, or active emissions all across the EM Spectrum.  Thanks to the inverse square law this can be done in an ideal vacuum at twice the range of the transmitter’s own detection range.  In order to be detected however, the signal must strike the craft, and more specifically the passive sensor receiver.  The practical effect of this is that even a wide beam EMAS wave cannot be detected unless it is pointing at the passive sensor.  Tight beam signals, like painting lasers can only be detected if the sensor passes in front of the beam’s path.

Neutrino Blue Ray Radiation Detector (NBRRD):

Neutrinos are elementary particles that travel close to the speed of light, lack electric charge and are able to pass through ordinary matter almost undisturbed.  This makes their detection extremely challenging.  Neutrinos were once thought to have no mass, but they are now known to have a minuscule (but non-zero) mass.  Neutrinos are created as a result of certain types of radioactive decay, nuclear reactions (fusion, fission or Anti-matter), or when cosmic rays hit molecules.  The interaction generated by neutrinos via the neutral current however is quite readily detected and so the majority of so called neutrino detectors work on this principle.

In a neutral current interaction, the neutrino leaves the detector after having transferred some of its energy and momentum to a target particle.  If the target particle is charged and sufficiently light (e.g. an electron), it may be accelerated to a relativistic speed and will consequently emit Blue Ray Radiation, which can be observed directly.  All three neutrino flavors can participate regardless of the neutrino energy.

NBRRD based detectors use specialized magnetic fields (neutrino traps) to capture and funnel neutrinos through the neutral current sensors.  Once Blue Ray Radiation is detected the neutrino trap refocuses to pinpoint the emitting ship’s location.  The fact that NBRRD are limited by the speed of the neutrino, below the speed of light, is generally not seen as a serious issue however because NBRRDs are used strictly as short range sensors, making relativistic issues virtually nonexistent.  

NBRRDs are also designed to be able to filter out the background neutrinos generated by a system’s local sun.  However it is a common tactic to use the sun to blind a NBRRD by placing one’s ship between the scanner and the sun, because the sun will overload the sensors ability to detect.  

Advanced NBRRDs utilized on capital scale ships have an additional trap that utilizes the charge current to determine neutrino flavor, these sensors can have up a 75% chance of being able to differentiate the type of reactor in use.  The table (Table 3) below illustrates the ranges for NBRRDs in an ideal vacuum assuming no jamming or outside interference. 

Table 3  NBRRD Detection Ranges

(These ranges represent an ideal vacuum; atmospheric ranges decrease by a factor of 10.)

Neutrino Detection Ranges	Small (KMe)	Medium (KMe)	Large (KMe)
Light Strike Craft / Shuttles	5,000	10,000	15,000
Heavy Strike Craft / Bomber	25,000	50,000	75,000
Civilian Transport	37,500	75,000	125,000
Corvette	75,000	150,000	225,000
Cruiser	100,000	200,000	300,000
Destroyer	125,000	250,000	375,000
Battleship / Heavy Carrier	150,000	300,000	450,000
Orbital Installations	250,000	500,000	750,000

Gravitic Sensors:

Possibly the most advanced and arguably the most important sensor system in use in the modern era the gravitic sensor is a somewhat misunderstood device.  The most common misconception is that the sensor detects the mass of the target.  This is only true in cases where the mass of the object is significant enough to actually generate a measurable gravitational field or at much closer ranges.  What a gravitic sensor does detect is the gravitational distortion generated by a ship’s artificial gravity system, anti-gravity systems, acceleration absorbers, Gravitational Deflector Fields (GDFs), gravitational engines, or slipstream fluctuations.

The gravitic sensor is considered such a significant sensor for four primary reasons:  First the sensor range is extremely far, outclassing even the TAS by a factor of 10.  Secondly, the detection time is virtually nill, ships with powerful enough gravitic sensors are able to take a sweep of an entire system as soon as they arrive to assess the situation.  Third, the passive nature of the system does not betray one’s location to the enemy allowing light recon craft to zip through a system and take detailed scans with little chance of detection.  Though the inner workings of a gravitic sensor are highly complex and classified the basis of their function is simple, the specialized detectors react to and measure the disturbances created in a star system’s local gravity field generated by the presence of another gravitic field or mass.  Finally, at close ranges (1/10000 maximum range) the sensors can give detailed scans of unshielded targets.

Gravitic sensors can be fooled however.  The extreme range of the gravitic sensor is due to the gravitational fluctuations generated by the systems mentioned above.  When those systems are either not installed, or not in use, the effective range of a gravitic sensor drops up to 99%.  This is still in excess of an EMAS’ range, but less then that of the TAS.  However, it still retains its other capabilities.  Additionally, the presence of an even larger gravity field can hide a ship from gravitic sensors.  Whole capital ships can sometimes hide themselves in the regions around large gas giants.  Recent developments have also revealed stealth craft that can enter and exit slipstream undetected by gravitic sensors.  It is believed that the acceleration and deceleration on the slipstream is much lower then normal, keeping the local dark mater from fluctuating as severely.

Table 4 Gravitic Sensor Detection Ranges

(Ranges in or near a planetary gravity field decrease by a factor of 10,000.)

Sublight Gravity Detection Ranges	Small (KMe/LP)	Medium (KMe/LP)	Large (KMe/LP)
Light Strike Craft / Shuttles	200 million / 7.1	400 million / 14.1	600 million / 21.2
Heavy Strike Craft / Bomber	1 billion / 35.3	2 billion / 70.6	4 billion / 141.2
Civilian Transport	1.5 billion / 52.9	3 billion / 105.9	5 billion / 176.5
Corvette	3 billion / 105.9	6 billion / 211.8	9 billion / 317.7
Cruiser	4 billion / 141.2	8 billion / 282.4	12 billion / 423.6
Destroyer	5 billion / 176.5	10 billion / 353.0	15 billion / 529.5
Battleship / Heavy Carrier	6 billion / 211.8	12 billion / 423.6	18 billion / 635.4
Orbital Installations	10 billion / 353.0	20 billion / 706.0	30 billion / 1059.1

Stealth systems:

In general all combat vessels have some form of signature reduction incorporated into their designs.  As every new sensor has come along designers have tried to find some way to mask their ships from it and in some cases almost magic means of defeating sensors are put to use.

Prior to the development of nano-sheet there were three popular methods by which to hide a ship from detection by EM radiation.  The first was passive; designing the ship in such a way that its shape did not reflect the EM waves back towards the detecting ship.   The second was also passive and required the use of special materials that would absorb the EM radiation, EMRAM (Electro-Magnetic Radiation Absorbing Materials).  Both of these methods proved to compromise the design of the craft limiting its abilities, especially in the case of fighter craft.  The third method was Active Stealth systems which varied in their application.  The most popular AS systems utilized variable frequency EM Wave Transmitters that would send a return pulse to the seeking sensor that was half a wavelength off in order to cancel out most of the return pulse.

In more advanced ships, with nano-sheet armor, the need for stealth against EM scanners has largely been deemed unnecessary.  The proliferation of EMT shields also reduces the effective range of EM based scanners.  The combination of these two technologies can reduce the range at which a craft can be detected by up to 99% depending on scanner efficiency, making EM scanners effective only for short range identification and target mapping.

The proliferation and use of TAS has forced many designers to reconsider the application of older stealth technologies.  While EMT and GDF shields can limit the effective range of scanner system by up to 25% they cannot fully hide a ship from Tachyon based sensors.  Therefore more radical changes have been implemented. 

It is well know that certain shapes will help to hide a ship from TAS scans there has been a trend back towards designing ships with stealthy shapes.  This has proven to be successful and can reduce the effective detection range up by up to 40%.  Other groups have also tried to use a ship’s own tachyon trap to absorb the incoming sensor pulse.  This has the further drawback of additional power consumption increasing the chances of detection by NBRRD and passive EM scanners.  However the use of a tachyon trap can reduce the effective detection range by TAS by up to 30%.  The combined use of all these method can reduce the effective detection range of a TAS by up to 95%.

As yet there has been no proven method by which a ship’s design or systems can be tuned to completely hide it from gravitic sensors.  Turning off or masking a ship’s artificial gravity systems can reduce its gravitic silhouette but cannot eliminate it.  Ships that use any kind of gravitic propulsion have further issues, the gravitic drives creating massive gravitic silhouettes, except in rare cases.  For reasons that they care not to explain, or outright refuse to, elder races (Donvarion, Pharard, et al.) prefer to keep the secrets of their technology just that, secret.  It has been well illustrated, that their ships, despite using gravitic drives, are nearly impossible to detect at long ranges, and even at short ranges they are difficult to scan or lock onto.

Jamming systems / ECM / Decoys:

It is rare to find any combat starship (military or pirate) that does not carry some form of jamming system.  While the exact nature of individual jamming system varies, they tend to work by creating as much “noise” as they can.  This noise then overpowers the detecting sensors making targeting and detection difficult to impossible.  While the jammers are on, effected scanners, missile guidance systems, and even communications inside the effective volume of space will not function properly, even those of friendly units.  Most jammers will leave certain sensor and communication bands clutter free to keep from affecting friendly units, but the activation of the jammer will still cause interference.  Jammers are used when the enemy knows the craft using it is there because of the massive diffused signature that they generate.  Once inside the jamming field, most effected scanners will have their range reduced by up to 60%.

Decoys in modern use are little more then small units that once released create as massive a sensor signature as possible.  This attracts hostile fire and in particular missiles away from the deploying craft.  Decoys cannot make themselves appear to be the launching craft as some might like to believe, but try and make themselves the largest target, or in the case of optically based sensors blind the seeker. 

Currently the most effective decoys are so called microfusion decoys.  When activated, these detonate a minute fusion charge that lights up the EM spectrum, creates an optics blinding flash, disrupts tachyon flow, and generates a huge number of neutrinos.  Gravitic decoys are only in development as no known missile guidance system relies on the complex and expensive sensor type.