Janus(AS) Description

Janus(AS) is a computerised, networked, multi-sided, interactive, closed, real time or turn based, stochastic, variable fidelity system that simulates Army combined arms capabilities and elements of joint capabilities that influence land combat and humanitarian operations.


The current version of the software runs on low end PC’s running the linux operating system. It consists of over 200,000 lines of code in FORTRAN and C.


The system uses a central server running the actual simulation with up to 96 workstations connected via TCP/IP running the client Graphical User Interface (GUI) software. The software also has two additional network interfaces. The first is a gateway for data collection. When a data logger (developed by DSTO) is active, Janus(AS) will attempt to connect to it at startup and send event messages for real-time data analysis. The second interface is a two-way connection that allows Janus(AS) to communicate with other systems such as DIS/ HLA gateways, 3D viewers and alternate user interfaces.


By default, the system is configured to operate with 3 sides: friendly (blue), enemy (red) and neutral (purple). However, the system supports up to 96 ‘forces’ each of which can be configured to be an independent ‘side’. The relationship between each pair of forces can be defined as friendly, hostile or neutral. These relationships are independent: that is just because force A is friendly towards force B, the relationship is not necessarily mutual and force B may be neutral or hostile towards force A. The relationship may be changed at any time during the scenario by exercise control. Forces can also be configured to share information with ‘friends’.


Each force is controlled by a single ‘interactor’ using the GUI. This allows the interactor to give orders to the entities under their control and to receive feedback from those entities regarding what they detect in the simulated battlefield. The GUI uses a scalable top-down map view, and a point and click menu to control and view the battlefield. Orders include: movement, direct fire, indirect fire, and mounting and dismounting passengers. Within each force, entities can be grouped into up to 10 groups, and/ or into ad hoc formations. The interactor can issue orders to groups and formations as well as individual entities.

A variety of ‘automated behaviours’ are also available that allows the interactor to set how entities will react to events such as detection of enemy, engagement by enemy and encountering mines and obstacles.

Most orders that an interactor can issue can also be attached to a movement node so that complex operations can be scripted. This includes the use of ‘trigger’ nodes that can cause other entities to start or stop moving, start or stop firing artillery and other similar events that may require synchronisation. In this way the simulation can also operate in a non-interactive mode.


During the scenario execution, each interactor is only able to see on their GUI the forces they control and entities from other forces that have been observed by their own force.

Optionally, forces can be configured to share information with their friends to represent combat tracking systems. This allows an interactor to display a snapshot of friendly forces and those enemy currently observed by friendly forces. This is often referred to as blue force tracking and red force tracking. Additionally, exercise control has access to ‘control workstations’. These can be configured to display any combination of forces to provide controllers with an overview of the battle. These workstations also have a limited control and intervention capability.

Real Time

Once started, the simulation operates in real time mode. That is, the simulation runs continuously, displaying and updating the current state, while the interactor concurrently issues new orders.

The ratio between ‘real time’ (ie the wall clock) and simulation time is also adjustable so that the simulation can run faster or slower than real time.

Turn Based

The software has the capability to ‘pause’ the simulation clock, while still allowing the interactors to continue issuing orders and planning. This can be used to operate in a turn based mode where interactors can input orders while the clock is paused, before allowing the clock to resume for a short period of time to execute those orders. This provides a very high level of control over the actions of the entities, but greatly increases the time to complete a scenario.


Most of the algorithms used in the simulation are based on probability tables and similar models that include some form of randomisation.


As well as the real time simulation, the system includes data editors, scenario editors, data collectors and report generators and a replay tool. Add on systems have included 3D displays, data loggers, DIS gateways, battle management systems and an agent based artificial intelligence engine.

Variable Fidelity

Because of the nature of the probability based algorithms many elements of the models can be adjusted to reflect different degrees of granularity. For example, the entities (represented graphically by ‘icons’) can represent a single instance of a platform or a homogenous aggregation of those platforms. The terrain resolution can be anything from 1m terrain cells to 1km cells. Similarly, all of the timing settings (such as the time between detection events) can be controlled to manage performance and resolution.


Janus uses a 3 dimensional terrain model that simulates large area terrain features (such as woods) and large bodies of water, that is overlaid with linear road and river features and urban features. Elevation is measured in 10ths of a meter, providing a high degree of precision in slope calculations.

It simulates all current Australian and notional enemy equipment and uses a simple table based database that allows new systems to be added quickly.

The simulation includes the following models: ground movement (tracked, wheeled, foot, marine), air movement (fixed and rotary wing), direct fire, indirect fire, suppressive fire, laser guided weapons, optical and thermal sensors, weapon locating RADAR, ground surveillance RADAR, airborne SAR RADAR, air defence RADAR, reactive armour, active defence systems, passenger transport, casualty evacuation, fuel and ammunition resupply, mine laying and clearing, obstacle creation and clearing (wire, ditch, roadblock), bridge laying, smoke (artillery delivered, grenades and vehicle exhaust), and chemical weapons. Additionally, all of the models include run-time tracing that can be activated to interrogate how the simulation is calculating the results of various events.

Army Combined Arms

The simulation represents most combat systems such as infantry, light transport, armour and armoured transport, close air, armed reconnaissance helicopters, artillery and mortars, combat engineering and first line resupply.

Joint Capabilities

The system models the transport, surveillance and close support capabilities of fixed wing and rotary aircraft, three classes of water craft (shallow, medium and deep draft) and amphibious vessels. Air and marine platforms can be used as surveillance, transport and fire support platforms. The terrain model supports littoral environments, islands and ship to shore operations.

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