Which ARPA feature uses the past positions to estimate the track?

• A. Rate Aiding
• B. Tracking gate
• C. Automatic target acquisition
• D. Smoothing

Answer: (D)

Smoothing uses past positions to estimate the track. By fusing a history of target measurements, it reduces radar noise and yields a steadier, more accurate estimate of the target’s current position and velocity, producing a smoother trajectory on the ARPA display. Other features rely more on current measurements or predictions from the radar, not on history-based estimation: rate aiding uses rate information to refine prediction, the tracking gate defines which measurements belong to a target, and automatic target acquisition initiates and maintains a track from new detections without smoothing past data.