Star Wars - Episode III.V - Rebellion Ascendant
Every ship can use its Sensors suite to try and jam another ship’s Sensors and/or Communications. Ships with additional Sensor Jamming Modules are better at it.
A ship’s Sensor operator may attempt to Jam Sensors or Jam Communications once per round as an action each. The operator must first pick a Sensor mode to use, Scan, Search or Focus. You cannot Jam Sensors using your passive sensors.
Scan: You attempt to Jam the area around your ship, on all arcs up to your sensors range. Roll Sensors with the additional Scan dice.
Search: You attempt to Jam the area at a specific Arc around your ship. Roll Sensors with the additional Search dice.
Focus: You attempt to Jam a specific ship. Roll Sensors with the additional Focus dice.
Sensor Jamming Modules add their rating as extra Dice to the total.
The Jam Sensors action produces a Target Difficulty that an enemy Sensor Operator must pass in a reactive Sensors check in order to successfully use their own Sensors or Communications. If both Sensors and Communications are being Jammed, each reactive check has a -1D penalty as per the normal multiple actions rules. Ships outside your Sensor range or outside the Jamming range may Communicate freely, but will still have to pass the Jamming Threshold to Identify your ship unless they are in an arc that is not being jammed.
Focus: The Opposing Sensor operator uses their Focus Dice on their Sensors attempt if they had detected your ship before the jamming started.
Search: The Opposing Sensor operator uses their Search Dice if they pick an arc and is the right one (otherwise, no extra dice are used).
Scan: The Opposing Sensor operator uses their Scan Dice if they attempt to beat the Sensor Jamming on all arcs. A failed Scan check determines the arc of the Jamming’s origin.
The Millenium Falcon is trying to Jam an Imperial Customs Frigate. The Falcon has detected the Frigate, while the Frigate has not detected that the Falcon is on its right arc.
Rolling the Sensors skill check with the additional Focus Dice, let’s say the Falcon rolls a total of 35. The Sensor Operator aboard the Frigate realizes they are being jammed, but doesn’t know from which direction. He can either guess an arc and take his Search dice as a bonus or play it safe and take his Scan dice instead. He decides to play it safe and rolls a total of 28. Because 28 is less than the Falcon’s 35, this round the Customs frigate cannot attempt to Detect or Identify ships. It can still communicate however and it signals any imperial ships in the area of pirate activity.
If the Falcon’s operator had devoted two actions to jamming both Sensors and Communications, then both Sensor Checks would be made with the standard -1D penalty for additional actions. The Customs Frigate Sensor Operator would then notice that both Sensors and Communications are being jammed. If they wanted to try and overcome both Jammings, he’d have to roll both reactive Sensor Checks at a -1D. Alternatively, they may not wish to use their Comm to signal for help and focus on overcoming the Sensor Jamming. In this case, the Operator would roll one reactive Sensor Check, without the -1D.
Detection is when your ship’s sensors pick up “something”. An energy emission, a planetary body, anything. Ranges for detection are given in a ships Sensors rating but a few abstractions need to be made in order to make sense.
- Hyperspace emissions (entering and exiting Hyperspace) can be detected at four times as far as the ship’s standard sensor range, because of their high fluctuations. No further detail is given other than “Something jumped in” or “Something jumped out”. A ship will still need to move within sensor range to pick up more information.
- Sensors can detect Planetary Bodies spanning an entire Solar System over a period of 2 minutes. This means that a ship is always capable to pinpoint its location in the system it is in as long as it has time to detect the planetary bodies surrounding it. In order to scan a planetary body, however, a ship will have to approach it.
- Long-range sensor scans are possible, in order to determine a ship’s position in the Galaxy, but this requires hours of Sensor Readings and triangulation. A ship in space with absolutely no indication of where it is, begins with a base Difficulty of Heroic + 35 (65). For each hour that a Sensors Operator spends using his ship’s Scan sensors, he reduces this difficulty by 5, up to a minimum of Difficult. Then, he may perform a Sensors check adding his Scan bonus dice to determine his approximate location in the galaxy. The results are never completely accurate, but the overall sector is easy to determine.
Once an object has been detected, a second Sensors Roll can identify it. Through Identification the following are gained:
- The Ship’s model
- If the Ship’s shields are on, or off
- The Ship’s active weapon systems
- The Ship’s transponder code
- If the Ship is charging its hyperdrive
- Once a Ship has jumped, a Very Difficult Sensors Check (no bonus dice) can determine the power of the Hyperdrive based on the residual emissions.
Once a ship has been Identified, each action spent by the Sensors Operator can reveal one of the above traits in the order they are presented. A Sensors Operator cannot spend more actions on this than he has Dice in the Sensors skill.