Enemy Detection is a passive Direction-Finding network for hostile ground activity. A station does not scan its whole network circle like radar and even a level-3 station does not reveal an enemy's true position. A contact appears only when at least one sensor in the network receives that enemy type.

The network. An active airfield can build and upgrade one Direction-Finding station in one of its two build sites, paid from the airfield's storage (see Airfields). Its network radius decides which nearby active sites can act as relay sensors; it is not the station's listening range. The airfield itself listens up to 30 km, while a relay listens up to 22 km before the enemy type is taken into account. If a site lies inside several networks, it is assigned to the nearest covering station and uses that station's level and calibration.

Different emitters can be heard at different distances. These are the maximum effective ranges in ideal conditions; the probability is already close to zero near the outer edge.

Receiving a contact. Detection is not guaranteed inside the effective range. The chance is highest close to a sensor, about 71% at half range and falls to zero at the edge. The result remains stable during a ten-minute detection period and is evaluated again for the next period. A stationary enemy can therefore appear or disappear when a new period begins.

Every successful sensor produces a bearing cone without range information. Station level, calibration and darkness determine its width. Distance also contributes to the map's A, B or C quality rating. The following values are the approximate full opening of a daylight cone before a Control Centre bonus:

Night widens the full cone by another 16 degrees at level 1, 8 degrees at level 2 and 4 degrees at level 3. Calibration cannot remove this night error.

Calibration. Fly any player aircraft 3-6 km from the station at 300-900 m above ground and remain continuously inside the same 30-degree sector for 20 seconds. Leaving the distance or altitude band, or crossing into another sector, resets the current dwell timer. Each of the twelve completed sectors is stored separately and improves bearings arriving from that direction for every relay assigned to the station. Upgrading the station clears its calibration because the antenna has changed. Calibration remains at full quality for 180 server mission cycles, then fades linearly to zero by cycle 365. The flight itself is described in Calibrate a DF Station.

From bearings to a position. With no received bearing, the enemy does not appear in the public threat layer. One bearing produces a single cone. Two or more bearings produce crossed cones, but players must judge their overlap themselves until the world has a Direction-Finding Control Centre.

The Control Centre requires three Direction-Finding stations at level 2 or higher. Once built, its global plotting service narrows every cone by 4 degrees on each side and automatically intersects two or more bearings. An intersection larger than 5 km² appears as a red plotted area. An area of 5 km² or less appears as a fixed point. That point is the calculated centre of the bearing intersection, not access to the enemy's hidden true coordinates.

Reading the Live Map. The normal THREATS layer draws each unresolved bearing as a red cone made from five progressively fainter bands. Every cone is displayed with the same cosmetic length of 10 km. Only its direction and opening angle carry information; the drawn length is neither an estimated enemy distance nor the sensor's detection range. A single bearing and unresolved crossed bearings have no contact marker, so their overlap must be judged visually. Once a contact becomes plotted or fixed, its ordinary dim cones are replaced by the red error area or point. The tooltip gives the enemy kind, resolution and the contributing A/B/C bearing qualities. Selecting a station airfield highlights all bearings reported through that station, including reports from its assigned relay sensors.

Map layers. CAL displays the real 3-6 km calibration band as twelve 30-degree sectors around each station; completed sectors appear brighter according to their remaining quality. The experimental CLOUD layer draws every bearing over its full effective detection range at very low opacity. Overlapping cones become darker, but this is only optical assistance and does not calculate a fix. Its outer edge shows the maximum detection range, where the actual detection chance has already fallen to zero. Threat data is refreshed every 30 seconds.

• Calibrate a DF Station
• Respond to an Ambush
• Build a Project

• Ambushes
• Security
• Live Map
• Institutions
• A/N Direction Finding