Question 8-44F5

This problem describes a persistent display artifact in a digital RADAR system: a bright, wide ring appearing at a fixed distance from the center on *all* digital ranges. The transmitter is operating normally. The RADAR receiver processes the reflected signals, which are then digitized and stored as "video" data before being displayed. This data is typically organized by range (distance from the antenna). * **B) Video storage RAM or shift register:** Digital RADAR systems use memory (RAM or shift registers) to store the processed video data corresponding to different range bins (discrete distance intervals). If a specific memory location or a group of adjacent locations corresponding to a particular range bin index (e.g., the 500th range bin out of 1000) becomes faulty, it could consistently output a high (bright) value. Since this fault is tied to a specific memory address or register stage, it will always appear at the same *relative* distance from the center on the display, regardless of the selected overall display range scale. A "wide" ring suggests multiple adjacent memory locations are affected. * **A) VRM circuit (Variable Range Marker):** The VRM generates a movable ring for measuring distances. A VRM fault would typically result in an unresponsive or incorrectly positioned movable marker, not a fixed, bright, wide ring that appears automatically on all ranges. * **C) Range ring generator:** This circuit creates the fixed, calibrated range rings (e.g., at 2, 5, 10 miles) for general reference. A fault here would likely affect the spacing, number, or presence of these standard rings, not create a single, extra, bright, wide ring at an arbitrary fixed distance. * **D) EBL circuit (Electronic Bearing Line):** The EBL generates a line from the center to measure bearing. A fault in this circuit would affect the bearing line, not a distance ring. Therefore, a defect in the video storage memory, which holds the processed return data for display, is the most plausible cause for a consistent, fixed-distance ring across all range scales.