CWIN Vol. 1, No. 5
The Daemon Mechanic
Sensor Systems and Countermeasures Part 1

Written by Michael Garrity
New Omaha Vehicular Association
garritym@hotmail.com

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.
 

Radar

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).
 

Partial Stealth

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.
 

Full Stealth

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.
 

Sonar

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.
 

Sound Amplification

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

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.
 

Ladar

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.
 

Infrared

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 below.
 

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.
 

Flares

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.
 

Hot Smoke

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.
 

Visual Sensors

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).
 

Camouflage

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

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).
 

Other Modifiers

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: