Physical Principles

Question 1

When a wave is reflected form a moving target, the frequency of the wave received is different form the transmitted wave

Answer 1

doppler effect

Question 2

Doppler effect occurs with relative motion between

Answer 2

source and receiver of the sound

Question 3

blood is moving target, transducer is

Answer 3

stationary source

Question 4

how many piezoelectric crystals are there

Answer 4

2, one constantly sending and one constantley receiving

Question 5

the reflected frequency is _________ than the transmitted frequency, depending on direction of flow

Answer 5

higher/lower

Question 6

employs a zero crossing freuqncy meter to display the signals graphically on a strip chart recorder

Answer 6

analog

Question 7

zero crossing frequency meter

circuitry counts each time the input signal crosses through

Answer 7

zero (baseline) within a time span

Question 8

zero crossing frequency meter

high freq waves have ______ oscillation, as low freq have _____

Answer 8

many, few

Question 9

zero crossing frequency meter

direction of blood flow varies during

Answer 9

cardiac cycle

Question 10

zero crossing frequency meter

machine estimates freq present in

Answer 10

reflected signal and displays them

Question 11

analog’s accuracy

Answer 11

acceptable

Question 12

analog drawbacks

Answer 12

noise, less sensitive

Question 13

when analog is active, what is done

Answer 13

self calibration

Question 14

individual freq displayed by Fast Fourier Transform method

Answer 14

spectral analysis

Question 15

spectral analysis more commonly used during

Answer 15

duplex evaluation

Question 16

spectral analysis time displayed on ______ axis, freq shift displayed on ____ axis

Answer 16

horizontal, vertical

Question 17

spectral analysis is free of many of the analog

Answer 17

recording drawback