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Physics 2 > Lecture 4 > Flashcards

Lecture 4 Flashcards

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1
Q

The reception channel of the beam former amplifies and combines the echo voltages from individual elements and sends them to

A

Signal processor

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2
Q

At the signla processor we are dealing with _____ signals

A

Digital

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3
Q

3 parts to the signal processor

A

Filtering
Detection
Compression

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4
Q

Pulsed wave US produces a ________ of transmitted freq

A

Bandwidth

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5
Q

_____ frequency is the strongest

A

Fundamental

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6
Q

We have a ______ of returning echo frequencies

A

Bandwidth

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7
Q

What is filtering

A

Getting rid of the frequencies in the bandwidth that are not important

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8
Q

When bandwidth is wide = SPL is

A

Slim

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9
Q

Is a wide bandwidth good

A

Yes

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10
Q

Filter passes _____

A

Range of frquency

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11
Q

The filter reject ____ and ____ the filter bandwidth

A

Above and below

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12
Q

What is harmonics

A

Modification of the sinusoidal waveform as it propagates through the tissue

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13
Q

Multiple frequencies are produced as harmonics by

A

Fundamental frequency

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14
Q

What do harmonic frequency produce

A

Echoes that will allow for better resolution

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15
Q

What performs harmonic function

A

Filters in sign processor

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16
Q

Echos from _____ and ______ are recieved at filter

A

Fundamental freq and second harmonic echo bandwidth

17
Q

At the signal processor, the __________ is filtered out

A

Fundamental frequency

18
Q

When is the filtering of the fundamental frequency occur

A

When we press THI

19
Q

Benefit of harmonics in a narrower beam

A

Better lateral resolution

20
Q

Benefit of narrower in the z plane

A

Better elevation resolution

21
Q

Why do harmonics eliminated side/grating lobes

A

Because they are not strong enough to generate harmonics

22
Q

Harmonics also benefit by the reduction of _______

A

Reverberation

23
Q

Anterior reverberation is aka

A

Main bang

24
Q

Reflections between the transducer face and skin surface cause

A

Multiple horizontal lines of echoes to appear in the near field

25
Q

Where is a common spot fot anterior reverb to occur

A

Happens at the ribs

26
Q

Why do harmonics lead to a smaller chance for anterior reverb

A

The main bang ehcoes are filtered

27
Q

Overall benefits of harmonics

A

Better detailed resolution
Reduced artifacts
Less grating lobe artifacts
Less anterior reverberation

28
Q

Draw back 1 of harmonics

A

Decrease penetration

29
Q

Drawback of 2 of harmonics

A

Worse axial resolution

30
Q

Why does harmonic give worse axial resolution

A

The transducer must fit the bandwidths of both F0 and 2F0

Therefore the bandwidth on each will be small compared to the overall bandwidth of the transducer

Physics 2 (11 decks)

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