Beam former

Question 1

number of cycles per second is called?

Answer 1

Frequency

Question 2

number of pulses per second?

Answer 2

PRF

Question 3

Number of pulses per scan line?

Answer 3

ensenble length

Question 4

ensemble length on dopper?

Answer 4

3-30

Question 5

ensemble length on 2D?

Answer 5

1

Question 6

of cycles in a pulse on 2D and doppler?

Answer 6

2D- 2-3

Doppler- 5-30

Question 7

what affects PRF in B-mode?

Answer 7

penetration/ depth

Question 8

grating lobes are produced by?

Answer 8

arrays

Question 9

3 ways to fix grating lobes?

Answer 9

1. apodization
2. THI
3. subcidy

Question 10

what affects NZL?

Answer 10

• frequency

- aperture sizer/ diameter

Question 11

U/S systems are what kind of system?

Answer 11

pulse-echo systems

Question 12

u/s systems determine what?

Answer 12

strength and location of echo-generating site

Question 13

the location of an echo is determined by? (2)

Answer 13

• arrival time (depth)

- direction of returning echoes

Question 14

4 main sections of intrument?

Answer 14

1- beam former
2- signal processor
3. image processor
4. display

Question 15

what 8 things are involved in the beam former?

Answer 15

1) Master Synchronizer*
2) Pulser
3) Pulse delays
4) Transmit/Receive Switch
5) Amplifiers
6) Analog-to-Digital Converters
7) Echo delays
8) Summer

Question 16

beam former involves?

Answer 16

• transmission and reception

Question 17

what are transmission channels?

Answer 17

• each path to each individual element is a channel

Question 18

what are reception channels?

Answer 18

• each path from each individual element

Question 19

beam former- components of transmitter? (4)

Answer 19

• master synchronizer
• pulser
• pulse delays
• T/R switch

Question 20

beam former- components of receiver? (4)

Answer 20

• amplifier (TGC, overall gain)
• analog-to-digital converters
• echo delays
• summer

Question 21

what is the master synchronizer?

Answer 21

• coordinated the entire system
• tells pulser when to fire
• T/R switch functions

Question 22

master synchronizer prevents?

Answer 22

• range ambiguity (incorrect placement of echo along scan line)

AKA echo-misplacement

Question 23

what is the pulser?

Answer 23

• produces electric voltages that drive the transducer

Question 24

operating frequency range?

Answer 24

from 2-20 MHz

Question 25

PRFvolt= PRFpulse what are the typical values for 2D?

Answer 25

4- 15 kHz

Question 26

PRF?

Answer 26

- operator controlled in doppler - automatic in grey scale - depth of image will determine PRF

Question 27

PRF is limited by?

Answer 27

depth

Question 28

what is the pulser?

Answer 28

- all echoes from one pulse must be received before the next pulse is emitted

Question 29

pulser- deeper images?

Answer 29

- echoes take longer to return | - decreased PRF and FR and Temp. res

Question 30

Beam former- What happens if we go over 77 cm/ms?

Answer 30

- range ambiguity

Question 31

What happens to the PRF in 2D if depth is increased by 4 x?

Answer 31

- PRF must drop 4x to prevent range ambiguity

Question 32

Pulser can be controlled in terms of?

Answer 32

power output

Question 33

transmission channels typically there are how many?

Answer 33

64, 128, 192

Question 34

Pulse delays?

Answer 34

- involved in sequencing arrays | - multiple blocks of sound, each producing a scan line

Question 35

what instument of the beam former is involved in phasing?

Answer 35

pulse delays

Question 36

how much time is between element firings?

Answer 36

< 1 microsecond delays between element firings

Question 37

what can pulse delays affect?

Answer 37

Can affect our near zone length (natural focus) Can affect our beam width at the focus How does this affect our image? Lateral resolution

Question 38

pulse delays are involved in?

Answer 38

- dynamic aperture control - apodization - coded excitation

Question 38

pulse delays are involved in?

Answer 38

- dynamic aperture control - apodization - coded excitation

Question 39

dynamic aperture control ?

Answer 39

pulser + pulse delays - decided the width of our aperture

Question 40

apodization?

Answer 40

Decreasing the strength to outer elements | Reduction of grating lobes in arrays

Question 41

Coded excitation allows for? (5)

Answer 41

``` multiple foci spatial compounding increased penetration ↑ contrast resolution B-flow imaging ```