Ground Sensor Operations Computer

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Description

The Ground Sensor Operations Computer is a high-level command and control computer for ground-based sensor systems. This component manages the execution of tasked sensor operations including search, surveillance, custody, characterization, and threat warning and assessment (TW&A) missions. The computer processes a prioritized command queue, coordinates tracking mount pointing, and controls sensor activation based on target access windows and elevation constraints. It provides autonomous execution of scheduled observation tasks for space domain awareness applications.

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Example Use Cases

• Space Surveillance: Execute scheduled observation tasks to detect and track resident space objects.
• Satellite Tracking: Perform custody observations to maintain track on specific objects of interest.
• Search Operations: Conduct systematic sky searches to detect new or untracked objects.
• Threat Assessment: Support threat warning and assessment observations for high-priority targets.

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Module Implementation

The Ground Sensor Operations Computer is a Computer component that attaches to a Ground Station and manages sensor tasking and execution.

Operating Modes

The computer supports multiple operating modes for different mission types:

Mode	Description
Idle	Awaiting new commands with sensor disabled
Search	Actively searching for objects at commanded positions
Surveillance	Monitoring a region of space
Custody	Maintaining track on specific objects
Characterization	Detailed observation of object properties
TW&A	Threat warning and assessment observations

Command Queue

Commands are processed through a priority-sorted queue. Each command packet contains:

Field	Description
Sensor ID	Identifier for the target sensor
Priority	Execution priority for queue ordering
Task Type	Operating mode to execute
Timestamp	Scheduled execution time
Access Message	Target pointing information
Duration	Observation duration

Commands are executed when the simulation time reaches their scheduled timestamp, in priority order.

Search State Machine

The search operating mode follows a defined state sequence:

State	Description
SetAlignment	Configure tracking mount pointing from access message
WaitForAlignment	Wait for mount to achieve commanded orientation
CaptureImage	Enable sensor and collect data for specified duration
DisableSensor	Shut down sensor and return to idle mode

Alignment Verification

During search operations, the computer verifies that the tracking mount has achieved the commanded orientation before enabling the sensor:

$$\text{aligned}=\Vert [LP{]}_{\text{actual}}-[LP{]}_{\text{commanded}}\Vert \le ϵ$$

where $[LP]$ is the direction cosine matrix from the local frame to the platform frame and $ϵ$ is the alignment tolerance (0.01).

Elevation Constraints

Commands are rejected if the target elevation is below the ground station’s minimum elevation limit:

$$\text{execute}=ϵ\ge {ϵ}_{\text{min}}$$

where $ϵ$ is the commanded elevation angle and ${ϵ}_{\text{min}}$ is the station’s minimum elevation constraint.

Capture Timing

The sensor capture duration is controlled by comparing the current time against the capture end time:

$$t_{\text{end}}=t_{\text{start}}+\Delta t_{\text{duration}}$$

The sensor remains enabled until $t\ge t_{\text{end}}$, after which it is shut down and the computer returns to idle mode.

Idle State Machine

When no commands are active, the computer operates in idle mode:

State	Description
DisableSensor	Ensure sensor is powered off
AwaitCommand	Wait for new commands in queue

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Assumptions/Limitations

• Only the search operating mode is fully implemented; other modes are placeholders for future development.
• The computer assumes a single CCD sensor is available on the tracking mount.
• Commands with elevation below the station minimum are silently skipped without notification.
• The alignment tolerance is fixed at 0.01; it is not configurable.
• Commands are removed from the queue after execution regardless of success or failure.
• The computer does not validate command timing conflicts or overlapping observations.
• Sensor warm-up time is not modeled; the sensor is assumed ready immediately upon enable.
• Access message validity is checked only at command execution time, not during queue insertion.