An annular array comprising 4 ringed elements transmits ______ down each scan line, each with a different ______.

An annular array comprising 4 ringed elements transmits ______ down each scan line, each with a different ______.

• A. 4 pulses; Focal depth
• B. 3 pulses; Focal depth
• C. 4 pulses; Aperture size
• D. 5 pulses; Focal depth

Answer: (A)

An annular array uses its concentric rings to create multiple focal regions along the scan line. With four rings, each ring can be driven with its own timing to produce a beam that focuses at a different depth. So, down each scan line you effectively transmit four pulses, each focusing at a distinct depth. The aspect that varies among the pulses is the focal depth, which is determined by how the rings are excited and delayed. The option that mentions aperture size doesn’t fit because the description focuses on the distinct focal depths produced by the rings rather than changes in the array’s aperture.

An annular array uses its concentric rings to create multiple focal regions along the scan line. With four rings, each ring can be driven with its own timing to produce a beam that focuses at a different depth. So, down each scan line you effectively transmit four pulses, each focusing at a distinct depth. The aspect that varies among the pulses is the focal depth, which is determined by how the rings are excited and delayed. The option that mentions aperture size doesn’t fit because the description focuses on the distinct focal depths produced by the rings rather than changes in the array’s aperture.