Written by Michael Garrity
New Omaha Vehicular Association
Web Posted July 04, 2048
Updated August 05, 2000
A modern Car Warrior who wants to increase his
chances of finding a target has a number of different sensor systems to
choose from. Each of these systems has different advantages and vulnerabilities
which are listed below. Note this article assumes that the rules for spotting
(or some modified version thereof) are in effect.
One of the most well-known of all long-range detection systems, radar was developed in the 1930s and came into full use during WWII. Radar is an active sensor which sends a beam of electromagnetic energy towards a target and analyzes the return echoes. Only general information about the target (speed, position, bearing), is gained.
Stealth (the most effective means of avoiding
radar detection) consists of using radar-absorbent materials (RAM) and
subtle alterations in a vehicle's structure to reduce a vehicle's radar
signature. There are two levels of stealth available: partial and full
(both discussed below). A less-expensive solution is to use chaff, which
gives a straight -6 penalty for all radar-based to-hit rolls, as well as
those made for spotting (assuming the chaff counter remains between the
target and the radar source).
Fitting this system to a vehicle consists of applying
anti-radar paints (like the "Iron Ball" paint used by the U.S Air Force)
and making slight alterations to a vehicle's surface. Use of partial stealth
takes up none of the vehicle's internal spaces, however it must be specified
when the vehicle is constructed. Partial stealth costs $1,000 per space
of size (including turrets) and gives a -4 penalty to any attempts to spot
the vehicle by radar. Attempting to use radar-based weaponry (missiles,
radar-directed guns, etc.) against a vehicle equipped with partial stealth
incur a to-hit penalty of -3.
This system is the kind of signature-suppression
built into such vehicles as the B-2 Spirit, the F- 117A Nighthawk and the
RAH-66 Comanche. Radar-absorbent materials are extensively used, along
with carbon-fiber composite materials. The outward appearance of a vehicle
with full stealth is radically altered (think of the Nighthawk or the Comanche).
Full stealth costs $5,000 per space of size (including turrets), applied
after modifiers for streamlining and armor sloping. It weighs 5 lbs. per
space of size and takes up 5% of the vehicle spaces (after armor sloping
and streamlining). Use of full stealth gives a -8 penalty to spot the vehicle
by radar. Additionally, radar-based weaponry has a to-hit penalty of -5.
Active sonar predates radar by about 10 years.
Instead of a beam of electromagnetic energy, active sonar used a beam of
sound. Otherwise, the principles of detection are the same. Like radar,
active sonar is easily detected. To counter this vulnerability, passive
sonar was developed. Passive sonar works by listening for any sounds generated
by the target. Sound baffling (also known as whisper- or stealth-mode)
disguises a vehicle's noise by using sound-absorbing materials in the vehicle's
structure (particularly around the engine compartment). The vehicle's engine
or propulsion system may also be specially-designed to emit less sound
than normal, and the vehicleís hull may also have an anechoic coating similar
to the rubber tiles fitted to some classes of submarines. As with stealth,
sound baffling is available in two types: partial and full.
Partial Sound Baffling
This system is commonly fitted to those vehicles
which commonly emit a great deal of noise, such as trucks and helicopters.
Rather than to avoid detection, this is done to make their use more acceptable
in crowded surroundings. Indeed, some jurisdictions may even mandate its
use. Partial sound baffling costs $500 and weighs 5 lbs. per space of vehicle
size, and gives a -3 penalty to spotting attempts made by sonar or sound-enhancement
systems. Against a target which has partial sound baffling, homing torpedoes
must make a to-hit roll of 5 or better.
Full Sound Baffling
This system is built into vehicles who are deliberately trying to avoid detection (common examples are the U.S Navy's SSNs and SSBNs, and some types of remote-control surveillance vehicles). Full sound baffling costs $2,000 and weighs 10 lbs. per space of vehicle size. Attempts by sonar or sound-enhancement systems to detect a target using full sound baffling incur a -5 penalty to the spotting roll. Homing torpedoes must make a to-hit roll of 9 or better in order to lock on.
Sonar systems and sound baffling are most effective
when the vehicle using them is travelling at low to moderate speeds. Vehicles
using these systems may travel at up to l/4 of their maximum speed with
no effect on the performance of sound baffling or sonar. Vehicles traveling
between l/4 and l/2 of their maximum speed have a -3 penalty to spotting
attempts made by their own sonar systems (this is cumulative with the penalty
from sound baffling on the target(s). Additionally, partial sound baffling
on a vehicle moving at these speeds is ineffective. The protection of full
sound baffling is reduced so that spotting attempts have only a -3 penalty.
The to-hit value for homing torpedoes is now 7.
Unlike sonar (which is designed to be used underwater),
sound amplification systems are designed to be used on land. They are passive
devices that amplify sound levels to a point where the sounds can be clearly
identified. A common example is the "parabolic microphone" used in surveillance
work. There are two methods of avoiding detection by sound amplifiers.
The first is to remain stationary. The second is to employ sound baffling
of either type (which provides the standard defensive penalties). Targets
which remain stationary and make no other sound can't be detected by sound
amplification systems. Stationary targets which make some other noise (crew
opening hatches, etc) reduce the defensive penalties by one. Sound amplification
systems aren't nearly as precise as radar, ladar or sonar. Accordingly,
they may not be used to guide aimed weapons fire. However, they may be
used to spot targets for attack by indirect fire.
Sonic sensors (also known as geophones) function
by picking up the rhythmic vibrations given off by moving targets. Targets
which are car-size can be detected at up to 100" range. Truck-or tank-size
targets can be detected at a range of 200". Small vehicle targets (those
the size of motorcycles or trikes) are detected at up to 50" range. Man-size
targets are detected at a range of 20". The main means of defending against
sonic sensors is to use a device known as a thumper, whose cost and weight
are listed in UACFH, p.107. When this device is in operation, no vehicles
within its radius of effect may be detected by sonic sensors. A personal
thumper is available for $500. It is 2 GE and it masks the movements of
pedestrians within 10". The detection ranges listed above assume that the
vehicle is moving at average (cruising speed). At a vehicleís top speed,
the detection ranges rise by 50%. Vehicles which are moving at l/4 or less
of their maximum speed reduce their detection ranges by 50%. Vehicles which
are stationary can't be detected at all by sonic sensors.
This high-tech detection system uses a laser beam instead of radio waves or microwaves. It has a shorter range than an equivalent-size radar set, but otherwise detects targets in the same fashion as radar (except that it provides more precise information; actual shapes can be determined, etc; for details see "A Short Look at Ladar" in CWIN Vol. 1, No. 5). Ladar can be foiled either by blocking line-of-sight between the ladar and its target or by using stealth. The main way to block line-of-sight is to use smoke of some kind. Smoke or hot smoke will block the passage of a ladar beam, thus depriving the scanning vehicle of its targeting information. Prismatic smoke (also known as "glitter smoke") will block a ladar beam, but will not interfere with visual or infrared scanning. This means that ladar rangefinders and targeting lasers do not work through smoke. Missiles with active-laser homing (ALH) also cannot target any vehicle so protected.
The defensive properties of smoke are useless
without some means of detecting a ladar beam. Accordingly, laser sensors
and laser-reactive webs were developed. Laser-reactive webs cost $100 per
armor location. They defend against ladar by being linked to a smokescreen
(at a cost of $50 per web). This causes the incoming ladar beam to automatically
trigger the smokescreen, thus blocking it. Note that a laser-reactive web
will not identify what kind of ladar beam is striking it, only that it
is being scanned. Laser sensors are a more sophisticated version of the
LR web. They cost $1,000 per space of vehicle size and provide universal
protection. Laser sensors will detect the use of ladar against a vehicle
equipped with them, and will also identify the type of laser device used.
The precision of laser sensors allows the user to determine where the ladar
beam is coming from.
The first type of infrared vision system was active IR. This system was experimented with during the late stages of WW II, but it is unknown how much battlefield use this system actually saw. Active IR consists of a light source which has been shielded to emit mainly in the IR frequencies. The vehicle which carries the IR source (or its crew) is equipped with filters which allow them to see the reflected light. This system shares the common vulnerability of all active sensors, in that its use can be easily detected.
The next type of infrared system is passive IR. Passive IR works by detecting the heat emitted by a target versus the heat of the target's surroundings. Targets which are much hotter than the surroundings show up as very bright images, while those which are cooler are very dark.
Thermographs are the latest generation of thermal sensors. They are one of the reasons why the U.S was able to manhandle the Iraqi Army with such ridiculous ease during Operation: Desert Storm. Thermographs are entirely separate systems. They do not require the vehicle to have an IR sighting system already fitted. Thermographs sense the heat variations of a target relative to those of its surroundings (as with passive IR) and convert the information thus gained into an image which has the quality of a black-and-white television picture.
Infrared cloaking (IR shielding) is the main method
of protecting against infrared sensors. It is available in the following
two varieties. Other means of defeating IR spotting attempts are also listed
Basic Infrared Cloaking
This system costs $1,000 per space of vehicle
size (including any turrets). Basic IR cloaking gives a -4 penalty to any
attempt made to spot a vehicle by using a thermograph.
Full Infrared Cloaking
Costs $5,000 per space of vehicle size (including
any turrets) and weighs 5 lbs. per space. It gives a -6 to any spotting
attempt made by thermograph.
Vehicles which are being attacked by IR-guided
missiles or scanned by IR systems may launch a flare or group of flares
to avoid being detected. A flare launcher costs $750, weighs 40 lbs., takes
up 1 space and has 1 DP. Flare launchers have 30 shots (CPS $50 and WPS
2 lbs.) and may fire l-3 per turn (userís choice). Flares burn for 5 turns.
A single flare gives a -1 penalty to the to-hit/spotting roll made by the
crew of an attacking vehicle. Additional flares give an additional -1 penalty
to the roll (up to a maximum of -3). A flare launcher protects a single
arc of fire. Multiple launchers must be fitted to protect a target from
multiple arcs. The spotting penalties of flares and IR cloaking are cumulative.
This substance is commonly used to defeat laser-based detection attempts. However, it is also useful against IR systems. Every l/2" of hot smoke between the target and an IR system gives a -1 penalty to the spotting roll (maximum of -4).
Note: Sufficiently-sensitive passive IR and thermograph
systems are capable of tracking a man or animal by detecting the residual
heat in the footprints left behind. This also extends to being able to
detect where the person or animal touched something. Both of these detection
attempts must be made within 3-5 minutes of the targetís passing, or the
heat will have faded entirely.
Advanced Low-Light Television (ALLTV)
Other than the standard MK-1 eyeball, which has
served for thousands of years, the main type of visual sensor is the computer
spotter. This device (also known as ALLTV; Advanced Low-Light Television)
has the combined abilities of telescopic optics (-1 spotting penalty per
60" of range), light amplification (reduces darkness penalty from -3 to
-1) and image enhancement (gives +2 on target spotting rolls). A computer
spotter or ALLTV costs $10,000, weighs 25 lbs. and takes up 1/2 space.
In daylight, computer spotters give a +5 bonus to the spotting roll, along
with the benefits of telescopic optics. They do not work if the target
is obscured by smoke or dust, or if there is no ambient light (total darkness).
At its most basic, the art of camouflage consists
of breaking up a target's profile and concealing the target itself so that
the human eye will not be drawn to it. Camouflage is available in two different
types; passive and active.
Passive camouflage consists of painting a vehicle or target with an appropriate camouflage pattern (examples are woodland, desert tan and the "dazzle" pattern applied to WWII warships). Ground vehicles are then concealed within brush or underneath camouflage netting (which has cost and weight listed in UACFH, p.65). Passive camouflage gives a straight -2 penalty to spotting rolls, assuming that the vehicle so protected is stationary.
Special anti-radar/anti-thermograph netting is available at 4x the cost and 2x the weight of ordinary camouflage netting. This kind of netting gives a -1 to spotting rolls made by radar sets or thermographs (this -1 is cumulative with the penalties from infrared cloaking and stealth systems).
Passive camouflage doesn't work if the vehicle
is moving. The two levels of active camouflage (also known as "chameleon"
systems) are basic and instant.
Basic Chameleon System
This system is built into the surface of a vehicle
at the time of construction. It uses advanced liquid crystal display (LCD)
technology to copy the pattern of a target's surroundings and duplicate
it on the targetís surface. The process is rather slow, taking 10 turns
to alter the target's appearance. A basic chameleon system costs $250 and
weighs 1 lb. per space of vehicle size (including turrets). It gives a
-3 penalty to visual spotting rolls made against stationary targets. The
penalty is reduced to -1 if the target is moving (this is because the chameleon
system can't adapt fast enough to the changing surroundings).
Instant Chameleon System
As above, but with the addition of fiber-optic
light guides and superior computer processing power. The time required
for an instant chameleon system to change its appearance is only one turn.
A vehicle protected by it gives a -6 penalty to any visually-based spotting
rolls made against it. The penalty drops to -3 if the vehicle is moving.
Instant chameleon systems cost $1,000 and weigh 5 lbs. per space of vehicle
size. Unlike basic chameleon, an instant chameleon system can only be purchased
by governmental agencies (police departments, military units, etc).
The penalties listed in the above paragraphs assume that the sensor system in question is operating at or near its maximum range. In cases where the sensor is very close to a target, the following bonuses apply to spotting rolls: