week 6

Question 1

QRS Complex

Answer 1

a breakdown of parts of a ecg wave consists of:
PR interval
PR segment
QRS complex
QT segment
ST segment

Question 2

atrial depolarization occurs during the…

Answer 2

PR interval

Question 3

ventricle depolarization occurs during the…

Answer 3

QRS complex

Question 4

ventricle repolarization occurs during the…

Answer 4

ST segment

Question 5

when creating filters in matlab, N should be equal to

Answer 5

the length of the ECG wave

Question 5

what construct can we use to calculate symmetrical/asymmetrical filters?

Answer 5

for loop

Question 6

symmetrical filter for loop example

Answer 6

for i = 2:(N-1)
sym3(i-1) = (ECG(i-1) + ECG(i) + ECG(i+1))/3
end

Question 7

asymmetrical filter for loop example

Answer 7

for i = 1:(N-2)
asym3(i) = mean(ECG(i:i+2))
end

Question 8

3 classes of signal

Answer 8

periodic, aperiodic, step like (transient)

Question 9

square wave in matlab

Answer 9

use square function!
looks like square humps

Question 10

pulse train wave

Answer 10

small humps with wide gaps in between

Question 11

sawtooth wave in matlab

Answer 11

use sawtooth function!
looks like backwards N

Question 12

equation for sinusoidal wave form

Answer 12

x(t) = A sin(2 pi f t + 6)

A is the amplitude
f is the frequency
t is the period
6 is the phase

Question 13

T = ?
(T is phase)

Answer 13

1/f
(f is frequency)

Question 14

x(t) = ??

Answer 14

x(t + T)

t is time
T is period

Question 15

how many periods is required to completely define a periodic signal?

Answer 15

1
periodic means that each phase is the same

Question 16

aperiodic signal

Answer 16

exists over finite time frame but are zero before and after the time frame

Question 17

aperiodic signals are treated as ____ with a period that approaches ____

Answer 17

periodic
infinity

Question 18

operations can only be applied to ___ segments

Answer 18

non-zero

Question 19

how do you average data with different lengths?

Answer 19

interpolate the data before averaging

Question 20

transient signal

Answer 20

increases infinitely and doesn’t return to initial value, hardest to treat mathematically because any operation must be carried out to infinity

Question 21

what is the best way to gain insight on a signal?

Answer 21

compare to reference signal or family of related reference signals

Question 22

reference signals need to be…

Answer 22

known and not complex
ex: sin wav

Question 23

correlation

Answer 23

quantitative comparison between two signals

Question 24

correlation function in matlab

Answer 24

corrcoef(x, y)

Question 25

correlation coefficient

Answer 25

number that signifies similarity between two signals, this number is between -1 and +1

Question 26

crosscorrelation

Answer 26

correlating over many different time shifts or lags

Question 27

lag

Answer 27

continuous variable of time used to shift x(t) with respect to y(t)

Question 28

what is the result of crosscorrelation?

Answer 28

series of correlations between signals for different points in time.

like correlating x(t) and one second and y(t) at one second and storing that value, then doing it for two seconds and so on