Which signal is used to synchronize the coherent oscillator to a fixed phase relationship with the transmitted pulse?

Which signal is used to synchronize the coherent oscillator to a fixed phase relationship with the transmitted pulse?

• A. Coherent oscillator reset pulse
• B. Phase reference pulse
• C. Timing reference pulse
• D. Coherent oscillator lock pulse

Answer: (D)

Maintaining coherence means keeping a constant phase relationship between the transmitted pulse and the receiver’s local oscillator across pulses. The signal used for this is the coherent oscillator lock pulse. It provides a lock signal to the oscillator so its phase tracks the transmitter's phase, usually through a phase-locked loop, ensuring the phase reference stays tied to the transmitted pulse from one pulse to the next. This lock pulse is specifically designed to enforce and maintain that fixed phase relationship, which is crucial for coherent detection and accurate Doppler processing. In contrast, a reset pulse would only reinitialize or jumpt the oscillator, breaking coherence; a phase reference pulse or timing reference pulse supplies information about phase or timing but does not continuously enforce the ongoing phase lock between transmitter and oscillator.

Maintaining coherence means keeping a constant phase relationship between the transmitted pulse and the receiver’s local oscillator across pulses. The signal used for this is the coherent oscillator lock pulse. It provides a lock signal to the oscillator so its phase tracks the transmitter's phase, usually through a phase-locked loop, ensuring the phase reference stays tied to the transmitted pulse from one pulse to the next.

This lock pulse is specifically designed to enforce and maintain that fixed phase relationship, which is crucial for coherent detection and accurate Doppler processing. In contrast, a reset pulse would only reinitialize or jumpt the oscillator, breaking coherence; a phase reference pulse or timing reference pulse supplies information about phase or timing but does not continuously enforce the ongoing phase lock between transmitter and oscillator.