How does increasing PRF speed affect radar imaging?

• A. Increased Speed -> Decreased Detail of Image -> Increased Range
• B. Increased Speed -> Increased Detail of Image -> Decreased Range -> Increased rate of radiated target.
• C. Increased Speed -> Increased Range but decreased target accuracy
• D. Increased Speed -> No change in image quality

Answer: (B)

Increasing how often you pulse the radar (PRF) means you’re sending more samples of the scene per second. That higher sampling rate improves the processor’s ability to resolve fine details in the image, especially in the velocity/Doppler information, so the image quality or detail tends to improve. But the trade-off is the unambiguous range gets smaller—the maximum range you can measure without range aliasing is inversely related to PRF—so higher PRF reduces the clean viewing distance. At the same time, a higher PRF means the transmitter is emitting pulses more frequently, so the rate at which energy is radiated increases. Put together, the result is more image detail, a decreased unambiguous range, and a higher rate of radiated pulses.