Question 8-45F3

When a RADAR display shows "sectors of solid video" or "spoking," it indicates that the receiver is picking up strong, continuous signals from specific directions. This is a classic symptom of interference from other radar transmitters, particularly from nearby vessels. Here's why: * **Interference (Option C):** Other radar systems (especially those operating on similar frequencies or with powerful side lobes) transmit very strong pulses. When your radar antenna sweeps through the direction of another transmitting radar, your receiver will pick up these powerful direct signals. Unlike faint echoes, these direct transmissions are so strong that they can overload the receiver, appearing as solid lines or wedges (spokes) radiating from the center of your display in the direction of the interfering radar. This is a common occurrence in busy shipping lanes. Here's why the others are less likely: * **Antenna information circuits failure (Option A):** This would typically affect the accurate depiction of the antenna's bearing or rotation, potentially causing a frozen display, incorrect bearing markers, or erratic sweep, but not directly causing sectors of *solid video* from received signals in the way interference does. * **Frequency of raster scan (Option B):** The raster scan frequency relates to how the display itself is drawn. An incorrect frequency would likely cause distortion across the entire display or display timing issues, not specific directional "spokes" of received signal. * **Constant velocity of antenna rotation (Option D):** Variations in antenna rotation speed might distort the range or bearing of targets, making them appear stretched or compressed, but it wouldn't generate *solid video* spokes of strong, false targets.