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94 Cards in this Set
- Front
- Back
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A transducer that contains single, circular disc-shaped active element that is moved by a motor is called a ____ transducer.
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mechanical
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The ____ of a mechanical transducer creates the scan plane.
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movement
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The minimum number of active elements in a mechanical transducer is ____.
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one
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A mechanical transducer produces a ____ shape.
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fan/sector
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What type of steering do mechanical transducers have?
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mechanical
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There is a fixed ____ ____ w/ mechanical transducers.
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focal depth
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What are the 2 types of fixed focusing?
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internal and external
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What does internal focusing use?
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use of current active element
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External focusing is w/ the use of an ____ ____.
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acoustic lens
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There is only 1 crystal w/ a mechanical transducer so if there is damage to the transducer what happens?
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the whole entire image is lost
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Arrays contain multiple ____ ____.
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active elements
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T or F. Array transducers involve a single slab of PZT cut into multiple pieces.
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TRUE
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Each element of PZT in an array transducer is connected by a wire to its own ____.
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circuitry
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What is a channel?
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a combo of active element, wire, and the systems electronics
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Since each element in an array transducer has its own circuitry, what can the system do?
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it can excite single or groups of elements in various ways
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What are the types of array transducers?
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linear (phased array), annular (phased array), and convex (curvilinear array)
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With linear phased array transducers how are the active elements arranged?
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in a straight line
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With annular phased array transducers how are the active elements arranged?
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circular rings w/ a common center
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With convex/curved array transducers how are the active elements arranged?
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in a bowed/arched line
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A compact, small square transducer is known as the ____ transducer.
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linear (phased array)
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With the linear phased array transducer there are no ____ ____ and it contains about ____ elements.
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moving parts, 100-300
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How is the beam steered & focused w/ linear phased arrays?
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using phasing
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Each element w/ linear phased arrays is placed side by side in a line & is ____ & ____.
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rectangular & narrow
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The width of each element in a linear phased array transducer is ____ of the wavelength.
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1/4-1/2
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What is the image shape of a linear phased array transducer?
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fan/sector
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With linear phased arrays there is variable ____ & ____.
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depth & focus
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Electronic steering & focusing is used w/ linear phased arrays called ____.
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phasing
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Phased array ALWAYS means ____ or ____.
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adjustable or multi-focus
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If the electrical spike line is sloped than the sound beam is ____.
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steered
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If the electrical spike line is vertical, than the sound beam is ____.
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straight or unfocused
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The electronics w/in the US system that create the patterns of electrical spike line is called the ____ ____.
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beam former (get it? it's the former of the beam!)
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A curved pattern creates a ____ sound beam.
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focused
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A straight patten is ____.
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unfocused
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There is no slope w/ a curved pattern so it goes in a ____ ____.
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straight line
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The more curved the sound beam, the ____ the focus.
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shallower
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Slope=
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steering
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Curvature=
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focusing
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The focus is the "____" of the sound beam.
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waist
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Greater curvature occurs w/ a beam with ____ focus.
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shallow
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Less curvature occurs w/ a beam with ____ focus.
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deepest
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T or F. Focusing can also occur during reception.
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TRUE
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There are more accurate images w/ ____ ____ during reception.
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time delays
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T or F. The delay patterns during receive-focusing change continuously.
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TRUE
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Time delays during receiving that result in focusing is known as ____ ____ focusing.
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dynamic receive
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Transducers w/ an active element that is disc-shaped (bullseye) w/ multiple ring-shaped elements is a ____ ____ transducer.
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annular array (phased)
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Annular phased array transducers have a ____ shape and are _____ steered/rotated.
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fan/sector, mechanically
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With annular phased array transducers there can be multiple ____ ____ ____.
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transmit focal zones
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The inner crystal of an annular phased array transducer has a ____ focus beam & only collects info from ____ ____.
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shallow, shallow depths
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When one ring of the annular phased array transducer active element is damaged what happens?
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only a portion of the image will be lost (horizontal or side-to-side band of dropout)
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If the innermost ring of the active element in an annular array transducer is damaged what happens?
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most superficial region is lost/messed up
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If the outermost ring of active elements of an annular phased array transducer is damaged what happens?
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the deep image is lost
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A large acoustic footprint w/ rectangular images are characteristics of what transducer?
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linear sequential array
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There are ____ strips of PZT w/ linear sequential arrays & each crystal is ____ wavelength in width.
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120-150, 1
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T or F. W/ linear sequential arrays, some but not all of the crystals are fired simultaneously.
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TRUE
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The focus is ____ w/ linear sequential arrays.
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electronic
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How is transmit focusing achieved w/ a linear sequential array transducer?
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curved pattern excitation of active elements
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With transmit focusing w/ a linear sequential array transducer, the ____ elements are fired first than the ____.
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outer, inner
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What happens when an element in a linear sequential array is damaged?
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only the portion of image extending downward is affected (dropout)
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Linear sequential arrays can steer _____ & are _____ shaped.
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electronically, parallelogram
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Transducers that are bow/curved shaped are ____ transducers.
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Convex (curved, curvilinear) array
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A convex/curved transducer is made of 120-150 ____ shaped strips of PZT side by side in a ____ line.
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rectangular, bowed
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Each crystal in a convex/curved transducer is ____ wavelength wide.
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one
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T or F. With convex/curved transducers, some but not all crystals are fired simultaneously.
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TRUE
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Since the crystals w/ convex/curved transducers are in an arc, how do they travel?
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in different directions (sound beams not parallel to each other)
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W/ curved/convex transducers, the focusing is ____.
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electronic
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What is the shape of a convex/curved transducer?
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blunted-sector shaped
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T or F. When one element is damaged w/ curved/convex transducers only the portion of the image directly below is affected.
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TRUE
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A transducer that is a combination of a linear sequential & linear array is a ____ ____ transducer.
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vector array
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Vector arrays are also known as ____ ____.
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virtual sector
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There are ____ rectangle PZT's w/ vector arrays and a ____ ____.
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120-150, small footprint
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T or F. With vector array transducer, some but not all crystals are fired simultaneously.
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TRUE
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What type of focusing is used with vector arrays?
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electronic
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What is the shape of a vector array?
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trapezoidal (top of image is flat)
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Slice thickness resolution is AKA ____ _____.
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elevational resolution
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How is slice thickness resolution measured?
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measured perpendicular to the imaging plane or above-to-below plane
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What type of active elements have the best elevational resolution?
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elements that are disc-shaped provide the thinnest slices & best elevational resolution w/in the focal zone
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Disc-shaped crystals are found in ____ & ____ transducers.
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mechanical & annular
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Disc-shaped crystals produce beams w/ equal ____ & ____ resolution.
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lateral & elevational
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With phased array, linear array, and convex array transducers, the beam thickness @ the transducer is = to what?
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the height of the active element
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For the linear array, phased array, and convex array transducers the ____ resolution is best, followed by ____.
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axial, lateral
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What is a 1 1/2-D Array?
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new transducer w/ thinner beams and improved slice thickness resolution
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With the 1 1/2-D Array there are multiple crystal in the ____ & ____ direction.
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up & down
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What are side lobes?
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extra off-axis sound beams @ depths = to or greater than the focal zone
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Side lobes degrade ____ resolution.
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lateral
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What are grating lobes?
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similar to side lobes but created by array transducers
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Grating lobes also degrade ____ resolution and diminish ____ ____.
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lateral, image quality
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Since lobes create ____ we eliminate them!
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artifact
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How can we reduce side & grating lobes?
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by a process called apodization
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What does the process of apodization involve?
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stronger electrical signals excite the inner crystals, while weaker signals excite the outer crystals
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With apodization, lobes are ____.
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diminished
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A technique called ____ ____ is used to make a sound beam narrow over a greater range of depths.
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dynamic aperture
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Dynamic aperture improves ____ resolution over a wide range of depths.
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lateral
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What is the aperture?
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the listening hole or # of elements used to receive reflected echoes
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A machine that displays dopple & 2D images is called a ____ ____.
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duplex scanner
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