Lecture 2 P2 Flashcards
After the pulser in transmission channels is
Pulse delays
What do the pulse delays do (2)
Decide how many elements/crystals are involved
Decide which one fire and when
Pulse delays are involved in _________ in the way that they ______
Sequencing arrays
Create Multiple blocks of sound, each producing a scan ling
Pulse delays are also involved in _______ creating _____
Phasing/steering
Microsecond delays between elements firrings
Th electronic focusing of pulse delays
Microsecond delays betwee nelement firing
Curved delay pattern send sound beam to a focal point
Adjusting the delay places focus closer or farther away
Pulse delay dynamic apperature control
Decides the width of our aperture
Which affects
Our near zone length (natural focus)
Our beam width at the focus
Coded excitation of pulse delay
Normally sending one pulse per scan line —> ensemble length= 1
Can send multiple pulses per scan line
—> doppler ensemble length =3-30
CODED EXCITATION CAN BE
More complicated, send 1 pulse wiat then sen 2 pulse wait and change again
Coded excitation involves
Decoder in beam former
Pulse delays does involve _______ becuase
Range ambuguity because the decoder knows how it sent out
Coded excitation allows for (5)
Multiple foci Spatial compounding Increased penetration Increased contrast resolution B-flow imaging
What happens in B flow imaging
Multiple pulses are sent down the same scan line
Decoder stacks the received echoes —> constructive interference
What does constructive interference in B flow imaging allow for
Overall higher intensity echo
Makes even weak echoes seem brighter
Increased sensitivity -> able to pick up weaker echoes —> most important part
B flow is different than
B-MODE
