EM Profiles

The electromagnetic (EM) spectrum is divided into frequency ranges (or bands) based on the predominant manifestation of each range, with each band typically indicating a different source. Infrared radiation, for example, is a key output of impulse engines or power generation cooling systems. Ultraviolet radiation is a key output of beam weaponry.


The way in which EM is assessed by the EMDAR system may vary between EM bands, depending on that band's characteristics, which reflect the capabilities and limitations of the detection equipment. Some equipment may be less capable of analysing higher frequency EM has dissipation patterns, for example, which would make range estimates less reliable than for lower frequency EM.

These characteristics are stored for each vessel as EM profiles. Each vessel will have a different EM proifle and therefore may have advantages in detecting certain EM bands or at certain distances.

Offset Characteristics

How accurately the range of a detection can be calculated by a system is determined by offset characteristics (referring to how far the displayed range is offset from the actual range).

The offset modifier for each EM band is multiplied by a randomly generated number between -5 to 5 to produce the display offset. This is added to the detection's source location (as grid units) to determine the range actually displayed by the EMDAR array. This offset of displayed range vs actual range simulates the inaccuracies inherent in EMDAR.

Cutoff Characteristics

If a detection is too weak for the capabilities of the detection equipment, it may not be displayed by the system at all. This reflects the processing limits of detecting instrumentation, which will vary between bands. These are known as cutoff characteristics.

A separate random number betweeon 0 and 5 is generated. If this is above the cutoff value for the applicable band/level combination is above this value, no detection is displayed at all. 

Profile Levels

Each EM band profile includes five levels, each with different offset and cutoff modifiers than can be specified for a given detection intensity. This allows the simulator to provide a non-linear response, so that weaker intensities are less accurately ranged than stronger intensities. The intensities at which offset and cutoff characteristics apply may be varied between EM bands, so that one EM band may display more accurately at longer ranges than another EM band.

EM Profile Format

Each EM profile comtains five levels in this format:

levelx: {

   detect:  This is the detection intensity below which this level applies (see below)

   modify:  This is the modifier used to calculate the offset characteristic

   cutoff:  Any detection with an offset characteristic below this value will not be displayed


The system will use the first level encountered where the intensity is lower than the detect value. Levels should therefore be defined in ascending order unless a particular outcome is required.