Lecture 4

Question 1

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

Answer 1

Signal processor

Question 2

At the signla processor we are dealing with _____ signals

Answer 2

Digital

Question 3

3 parts to the signal processor

Answer 3

Filtering
Detection
Compression

Question 4

Pulsed wave US produces a ________ of transmitted freq

Answer 4

Bandwidth

Question 5

_____ frequency is the strongest

Answer 5

Fundamental

Question 6

We have a ______ of returning echo frequencies

Answer 6

Bandwidth

Question 7

What is filtering

Answer 7

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

Question 8

When bandwidth is wide = SPL is

Answer 8

Slim

Question 9

Is a wide bandwidth good

Answer 9

Yes

Question 10

Filter passes _____

Answer 10

Range of frquency

Question 11

The filter reject ____ and ____ the filter bandwidth

Answer 11

Above and below

Question 12

What is harmonics

Answer 12

Modification of the sinusoidal waveform as it propagates through the tissue

Question 13

Multiple frequencies are produced as harmonics by

Answer 13

Fundamental frequency

Question 14

What do harmonic frequency produce

Answer 14

Echoes that will allow for better resolution

Question 15

What performs harmonic function

Answer 15

Filters in sign processor

Question 16

Echos from _____ and ______ are recieved at filter

Answer 16

Fundamental freq and second harmonic echo bandwidth

Question 17

At the signal processor, the __________ is filtered out

Answer 17

Fundamental frequency

Question 18

When is the filtering of the fundamental frequency occur

Answer 18

When we press THI

Question 19

Benefit of harmonics in a narrower beam

Answer 19

Better lateral resolution

Question 20

Benefit of narrower in the z plane

Answer 20

Better elevation resolution

Question 21

Why do harmonics eliminated side/grating lobes

Answer 21

Because they are not strong enough to generate harmonics

Question 22

Harmonics also benefit by the reduction of _______

Answer 22

Reverberation

Question 23

Anterior reverberation is aka

Answer 23

Main bang

Question 24

Reflections between the transducer face and skin surface cause

Answer 24

Multiple horizontal lines of echoes to appear in the near field

Question 25

Where is a common spot fot anterior reverb to occur

Answer 25

Happens at the ribs

Question 26

Why do harmonics lead to a smaller chance for anterior reverb

Answer 26

The main bang ehcoes are filtered

Question 27

Overall benefits of harmonics

Answer 27

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

Question 28

Draw back 1 of harmonics

Answer 28

Decrease penetration

Question 29

Drawback of 2 of harmonics

Answer 29

Worse axial resolution

Question 30

Why does harmonic give worse axial resolution

Answer 30

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