Lesson 3: SenCom

Excerpts from "The Fundamentals of Military Sensory Technology.  Third Edition - Revised and Expanded" by Admiral Westend

Sensors

Starships have a wide array of sensors to detect other ships, planets and any potential hazards; the sensor operator uses his sensors skill.  Sensors difficulty numbers are based on the range to the target and modified by any objects or situations which may affect the sensors' readings.  For example, it is much easier to detect a ship in open space than one hiding in an asteroid belt.  One sensors roll can be made per round and the ship detects anything with a difficulty lower than the roll.  Sensors can perform two distinct tasks: detection and identification.

When a sensor detects something, it means that it notices the object, but cannot identify exactly what it is.
"There's a ship out there... but it could be a freighter or a fighter."

 When a sensor identifies something, that means that the sensor has determined the specific type of ship or object.
"Its definitely a freighter.  Scanner identifies it as a Corellian YT-1300.  Look at the power signature... he's carrying around a lot of weaponry."

The base difficulty to find a ship with sensors depends on the mode the sensor is in: passive, scan, search or focus.  Objects must be within the appropriate range to be detected.  Note that military vessels differ substantially; refer to the ship database for details on a specific ship sensor package.

Sensor Mode Detect Identify
Passive Moderate Very Difficult
Scan Easy Moderate
Search Easy Difficult
Focus Very Easy Easy

Modifiers

+1D or more to difficulty: Target is using a sensor mask
+5 to the difficulty to identify only: Target is using a sensor decoy (sensors detect both the ship and the decoy as "real" unless difficulty is beaten.)
+5 to the difficulty: Target ship's sensors are in passive mode.
+15 or more to difficulty: Target ship is running silent.
+10 or more to the difficulty to identify only: Target is jamming sensor readings.
+10 or more to the difficulty: Ship is hiding behind a planet or other massive body.
+20 to the difficult: Ship has other mass objects, such as asteroids, to hide among.
+5 to sensors roll: Targeting a small natural body, such as an asteroid.
+10 to sensors roll: Target is the size of a capital ship.
+10 to sensors roll to detect only: Target is jamming sensor readings.
+10 to sensors roll: Target is a moderate-size natural body, such as a larger asteroid.
+20 to sensors roll: Planetary or moon-size natural body or a Death Star-scale ship.
+30 or more to sensors roll: Stellar object such as a star, nebula, or black hole.

If the sensor operator beats the difficulty by 10 points or more, he can pick out the ship's transponder code.  Every ship that operates in Imperial space is required to register with the Bureau of Ships and Services (BoSS).  Of course a ship may have altered its transponder code, which is a Class-Three Imperial Infraction.

Sensor Modes

Starships sensors have four possible modes: passive, scan, search and focus.  All sensor modes have two numbers, listed as such: 80/1D.  The first number is the range of the sensor in "space units" from the ship's current position (i.e. radius).  The second number is the number of dice added to the operator's sensors skill.  A typical sensor's listing may be found below in the diagram section.

Passive

Sensors in passive mode are merely receiving information about the immediate vicinity of the ship.  Because the sensors are not sending out any signals, ships running in passive mode are harder to detect than ships using the other modes.

Scan

Scan mode sends out pulses in all directions at once to gather information about the surrounding area.  Scan mode ranges are greater than passive ranges and capable of detecting more information.  Because scan mode is an "active" sensor mode, it basically broadcasts your presence to anyone within that range.

Search

Search mode has the longest range and are more powerful that scan mode, but only one arc may be searched at a time (front, left, right, or back).  No information is received from any of the three arcs that the sensors are not searching.

Focus

Sensors in Focus mode are concentrating on a very small area, but yielding the most detailed information.  The range specified is the radius of the focus area, which may lie anywhere within the vessel's search range.  Sensors in focus mode receive no information about any other area of space.

Off

While not technically a sensor mode, sensors can be shut down completely.  The ship will receive no outside data from any of its sensor systems.  This is required in order for a ship to be running silent.

Sensor Countermeasures

Starships have a number of devices and techniques to avoid detection.  These are collectively known as "countermeasures."  While techniques may be used by virtually any starships, the devices must be specifically installed on the starship to be used.

Techniques

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Sensors are essentially "line of sight," any ship can "hide" behind a planet or other sufficiently large stellar body.  It is still possible for a scanning ship to pick up emissions of a hiding vessel though.  So while it makes detection substantially more difficult, it isn't impossible to detect a hiding ship.
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Ducking into an asteroid field has the tendency to confuse sensors because of the presence of many mass objects of various sizes moving in an erratic manner.
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If your ship is using passive mode sensors, you are less likely to be detected.
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A ship can also run silent.  Essentially the ship powers down all major systems, including engines, weapons, and shields.  The ship is adrift in space, with only life support systems and auxiliary power only.  Ships can seldom run silent for longer than five minutes before life support systems must be shut down for lack of power.  A ship running silent is even more likely of remaining undetected at long distances.
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Any ship can use its sensors to jam or flood an area of space with static.  This is almost sure to reveal the presence of the jamming ship, but the enemy will have a tough time determining the nature of the jamming ship.

Devices

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Sensor decoys are small pods or shuttles which duplicate the "sensor image" of the launching ship (or another ship in some cases).  When a decoy is used, it is more difficult for an enemy sensor operator to determine which signal is the correct one or if there are actually two or more ships.
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Sensor masks conceal a starships emissions, making it much more difficult to detect.
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False transponder codes give the ship a false registry.  All ships are required to register with BoSS (Bureau of Ships and Services), which assigns a unique transponder code to each ship's engines.  Clever captains can alter the transponder codes to identify the ship as another vessel.  While false transponder codes are difficult to create (and expensive to have someone else install) they make it easier for a ship to slip through customs.
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Cloaking devices almost completely hide a ship, both from sensors and visual detection.  Because the cloaking devices absorb all sensor radiation and light, it also makes them blind to their own sensor emissions.

Diagram

The diagram below details the sensor ranges for a Corellian Gunship (which probably has the weakest sensors of any capital ship).  Note that the grid size is the same used in most tactical displays, however the ships are shown larger than the grid scale so they may be more readily identifiable.  Examine the diagram to see the notes contained within (TIP: You must be using Internet Explorer 4.0 or better to view the hotspot tooltips.)

Sensors for the Gunship:
    Passive: 20/0D
    Scan: 40/0D
    Search: 80/1D
    Focus: 2/2D

Corellian Gunship using sensors in various modes. Remember that a ship may only use one sensor mode per round without multiple-action penalties. Passive Mode Range: For the Gunship is 20. Passive sensors do not emit any energy, but they receive little data. Scan Mode Range: For the Gunship is 40. Scan emits pulses in all directions to detect objects all around the ship. Asteroids and other large bodies can obscure sensors, effectively hiding anything behind them. The enemy gunship here is much harder to detect so long as it keeps its own emissions to minimum. Focus Mode Range: For the Gunship is 2. Sensors in Focus mode can usually give detailed information about a particualr target, but no information about anything else. Sensors can be focused anywhere within their Search range. Search Mode Range: For the Gunship is 80. Search sensors only detect objects in one arc at a time. Recon lines typically stagger their search pattern to cover all arcs at once. This enemy vessel is currently out of Scan range but within Search range. This target would not be visible unless the search arc was switched to starboard. These fighters are currently out of sensor range completely and cannot be detected.

 

Communications

Communication Systems

Starships normally have several communications systems, each of which serve a different purpose and some starships are also equipped with military grade Hypertransceivers and HoloNet Transceivers.  The following is an explanation of these systems from least to most powerful.

Intercoms

Intercoms are internal systems used to communicate between different sections of a starship.  They are usually "hard-wired" into the ship.  Note that many large ground vehicles and structures also have intercoms.

Comlinks

Comlinks are short-range two-way communication devices.  Smaller units are hand-held and most vehicles, buildings, and starships have an integrated comlink array to deal with comlink traffic.

Comms

Most starships have comms for ship-to-ship and ship-to-planet communications.  Starports use a pre-set comm channel to broadcast a METOSP ("Message to Spacers"), provide landing protocols, traffic patterns, conditions at the starport and other essential information.  Comms, like comlinks and intercoms, are lightspeed connections and are not practical to use at a distance beyond a few ligh-minutes.

Subspace Transceivers

Subspace transceivers allow for faster-than-light audio, video, and hologram communication, but their ranges are quite limited.  Small subspace transceivers may only reach a few light-years away, although high-powered units can reach a distance of well over 100 light-years.  Most starships have a subspace transceiver for distress signals and all military vessels use this method for non-critical communication among star systems within their territory, providing real-time communication.

Hypertransceivers

Hypertransceivers allow for instant, real-time audio or video communication anywhere within the galaxy.  It relies on a complex network of hundreds of thousands of transceiver satellites to transfer messages through hyperspace.  Because these systems are costly and consume a great deal of power, they are generally reserved for military vessels or extremely large commercial vehicles.

HoloNet Transceivers

The HoloNet is similar to hypertransceivers except that they add the ability for holographic communication.  This makes HoloNet Transceiver Statellites considerably more expensive and require substantially more power than hypertransceiver satellites and further limits its deployment to large military vessels and facilities.  The control of the HoloNet and the information transmitted through it is not taken lightly buy either the Galactic Empire or the New Republic.

Communication Frequencies

It is very difficult to find a communication signal without knowing its frequency and there are literally billons of different frequencies for comms and subspace communications.  There are established military and government bands for the Empire and New Republic, as well as "secret" frequencies for secured messages, which are often electronically scrambled.

Local governments regulate the use of frequencies for civilian, business, emergency services and military communications.  Groups may also use unauthorized frequencies for covert communications.  The following difficulties are for finding a specific kind of frequency.

Very Easy: 1-5

Listening in on a known, registered frequency.  Public communications, low-security corporate commnets.

Easy: 6-10

Listening in on a specific private frequency.  Low-security government communications such as emergency services.

Moderate: 11-15

Listening in on a somewhat sensitive communication frequency.  Local governments, sensitive businesses or security-conscious individuals.

Difficult: 16-20

Tapping professionally secure channels.  Lower-level Imperial or higher-level police bands.

Very Difficult: 21-30

Listening in on higher Imperial channels, or high-ranking government channels.

Heroic: 31+

Listening in on a top-secret Imperial, Rebel or New Republic frequency.

Coded Signals

If the signal is coded, the Communications Officer must make a decoding roll.  Some broadcasting devices have coding die codes, which adds to the broadcaster's communication skills when determining how difficult it is to decode the message.  By comparing the results on the chart below to determine how much can be decoded.  Note that some messages will also have code words - for example, Coruscant might be referred to as "Dewback" in a message.  At this point, the operator only know what was said about "Dewback" and must figure out what "Dewback" is.

Coder's roll is > decoder's roll by: Decoder learns:
6 Nothing can be made out
1-5 Decoder makes out wrong message
Decoder's roll is > coder's roll by: Decoder learns:
0-3 One or two garbled passages
4-6 About one-quarter of the information in the message
7-10 About half of the information in the message
11+ The entire message is unscrambled

 

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