What is range-rate in radar terminology?

• A. Range-rate is the rate of change of the range to the target, indicating radial speed.
• B. Range-rate is the angular velocity of the target.
• C. Range-rate is the rate of range measurement errors.
• D. Range-rate is the radar's range resolution.

Answer: (A)

Range-rate is the rate at which the distance between the radar and the target changes over time. It represents the radial component of the target’s velocity along the line of sight, basically how fast the target is moving toward or away from the radar. In Doppler radar, this radial speed shows up as a Doppler shift, allowing the radar to measure how quickly the range is changing. If the target is moving directly away, the range-rate is positive; if it’s moving toward the radar, the range-rate is negative (in terms of range reducing, the magnitude is the speed along the line of sight). The other ideas are different: angular velocity describes how fast the target’s bearing changes, while range resolution and range measurement errors relate to how precisely we can determine distance, not to the speed of that distance changing.