Lecture 16

Question 1

DOPPLER SHIFT=

Answer 1

REFLECTED FREQ - INCIDENT FREQ.

Question 2

DOPPLER SHIFT EQUATION

Answer 2

DS = 2 x SPEED OF REFLECTOR x OPERATING FREQ x COSINE/ PROPAGATION SPEED

Question 3

“2” IN DS EQUATION:

Answer 3

INITIAL ENCOUNTER W/SOUND WAVE AND REDIRECTION TO SOURCE.

Question 4

OPERATING FREQUENCY IS ______ RELATED TO MAGNITUDE OF SHIFT.

Answer 4

DIRECTLY

Question 5

VELOCITY OF REFLECTOR _______ PROPORTIONAL TO DOPPLER SHIFT.

Answer 5

DIRECTLY

Question 6

THE GREATER THE ANGLE (TOWARD 90 DEGREES) THE ______ THE COSINE.

Answer 6

SMALLER

Question 7

COSINE OF 90 DEGREES

Answer 7

0

Question 8

DOPPLER SHIFT FREQUENCY IS ___________ TO VELOCITY OF FLOW.

Answer 8

PROPORTIONAL

Question 9

• SENDS AND RECEIVES SOUND CONTINUOUSLY
• 2 ELEMENTS
• AUDIO AND WAVEFORM PRESENTED
• MEASURES HIGH VELOCITY FLOW ACCURATELY
• SMALL PROBE EASY TO MANIPULATE
• DISADVANTAGE - RANGE AMBIGUITY

Answer 9

CW DOPPLER

Question 10

DETERMINES DIRECTION OF DS

Answer 10

QUADRATURE DETECTION

Question 11

DETERMINES IF DS IS POS OR NEG.

Answer 11

BI-DIRECTIONAL DEVICE

Question 12

CANNOT DETERMINE IF DS IS POS OR NEG.

Answer 12

UNI-DIRECTIONAL DEVICE

Question 13

• 1 ELEMENT
• DS DISPLAYED AS WAVEFORM AND AUDIBLY
• DUPLEX SCANNING
• RANGE RESOLUTION (ABILITY TO DETERMINE DEPTH)
• DISADVANTAGE: ALIASING

Answer 13

PW DOPPLER

Question 14

IMPROPER REPRESENTATION OF A POS SHIFT AS A NEG SHIFT

Answer 14

ALIASING

Question 15

ALIASING OCCURS:

Answer 15

-WITH UNDERSAMPLING
-SAMPLING FREQ MUST = PRF
(PRF MUST BE 2x DS FREQ.)
-NYQUIST LIMIT EXCEEDED

Question 16

NYQUIST LIMIT =

Answer 16

1/2 PRF

Question 17

ELIMINATION OF ALIASING:

Answer 17

1. CHOOSE SHALLOWER SAMPLING DEPTH
2. INCREASE VELOCITY SCALE
3. ADJUST BASELINE SHIFT
4. CHOOSE LOWER FREQ TRANS.
5. USE CW INSTEAD

Question 18

SEPARATION OF MULTIPLE FREQUENCY COMPONENTS IN DOPPLER SIGNAL TO INDIVIDUAL ONES.

Answer 18

SPECTRAL ANALYSIS

Question 19

PURPOSE OF SPECTRAL ANALYSIS:

Answer 19

-PROVIDE QUANTITATIVE DATA ON DIFFERENT REFLECTORS

Question 20

SPECTRAL ANALYSIS IS ACCOMPLISHED BY:

Answer 20

FFT (FAST FOURIER TRANSFORM) PROCESSOR

Question 21

COMPLEX MATHEMATICAL PROCESS ANALYZING SIGNAL AND PRESENTING IN REAL TIME.

Answer 21

FFT (FAST FOURIER TRANSFORM) PROCESSOR

Question 22

INFO PW DOPPLER PRODUCES:

Answer 22

• VELOCITY FLOW
• DIRECTION OF FLOW
• RANGE OF FREQ.
• DURATION OF SIGNAL
• MAGNITUDE OF SIGNAL

Question 23

QUANTITATIVE DOPPLER MEASUREMENTS RELATE TO______________________.

Answer 23

PULSATILITY OF FLOW.

Question 24

PULSATILITY INDEX:

Answer 24

PI = MAX VELOCITY - MIN VELOCITY / MEAN VELOCITY

Question 25

RESISTIVITY INDEX:

Answer 25

RI = MAX (SYSTOLIC) VELOCITY - MIN.(DIASTOLIC) VELOCITY/ MAX VELOCITY