🔍 Key Concepts

• AFC (Automatic Frequency Control) purpose in radar systems • Which component actually oscillates at the radar transmit frequency • Which component provides a stable reference frequency for comparison

💭 Think About

• In a typical marine radar, what device generates the main transmitting RF pulse? • For AFC to work, it needs to compare the variable transmit frequency against something stable. Which listed component is normally used as a stable frequency reference? • Look at each answer choice and ask: which pair makes sense for a frequency comparison circuit rather than for power amplification or video processing?

✅ Before You Answer

• Identify which device in the options is the transmitter oscillator (high‑power RF source). • Identify which device or circuit in the options could act as a stable reference or frequency-sensing element in the receiver front end. • Eliminate any option where one of the pair is a video-stage component (after detection) or is not primarily used as a frequency reference.