Electrical Engineering: ECG Performance Practical Analysis Report

This practical assignment focuses on the performance analysis of an electrocardiogram (ECG) recorder. The experiment utilizes an oscilloscope and signal generator to measure key parameters. The methodology involves setting the signal generator to a 10Hz sine wave and adjusting the input voltage to achieve a specific deflection. The apparatus were arranged as shown in the circuit diagram. The experiment involves measuring the lead-1 position, connecting the black terminus to the signal generator, and recording peak-to-peak pen deflections for varying frequencies and amplitudes. Results are presented in the form of graphs illustrating frequency response and amplitude changes. The discussion section analyzes the linearity graph gradient, the type of filter used (low pass filter), and the cut-off frequency. The filter's role in removing unwanted signals and ensuring the fidelity of the 12-Lead electrocardiogram process is also explained. The gradient of the linearity graph does not agree with the sensitivity setting. This assignment provides a practical understanding of ECG recorder performance and signal analysis.

Performance of electrocardiogram 1
Performance of electrocardiogram.
Name
Institution
Date

Performance of electrocardiogram 2
Introduction
Electrocardiogram is defined as the activity that involves the use of electrodes placed on
the human skin to record the heart’s electrical activities over a given time period (Rodriguez,
2017). It is so far the commonly practiced form of measuring the physiological potential in
humans. In this practical the electrocardiogram instrument to be used is an oscilloscope. An
oscilloscope is an electronic test instrument that instantly displays and analyses electronic
waveforms by drawing a two dimensional graph of the signal voltage against time (Johnson,
Brush, & McTigue, 2016). The oscilloscope in this practical will be used together with a signal
generator in measuring some crucial electrocardiogram recorder parameters. A wave form simulator
will also be used to obtain test traces that will be recorded and analyzed.
Methods
Apparatus
 ECG recorder
 Oscilloscopes
 Signal generator
 Potential divider
 Crocodile clip lead
 ECG waveform simulator
Method Procedure
i. The output of the generator was set to 10Hz sine wave while the sensitivity of the recorder
set to 1cm/Mv
ii. The input voltage of the signal generator was adjusted to give a deflection of 30 to 35 units
for every change in frequency of input signals.
iii. The apparatus were arranged as shown in figure 1 below
iv. All the lead-1 position which uses yellow and red terminus were measured

Performance of electrocardiogram 3
v. The black terminus was connected to the earth of the signal generator side
vi. Peak-to-peak pen deflection of the recorder for peak-to-peak voltage of the signal generator
was recorded for the first 10 points
vii. Peak-to-peak pen deflection of the recorder for varying frequencies from 1 to 100 for a
constant input voltage was recorded.
viii. The results were used in plotting a graph.
Circuit diagram
Fig
ure 1
Discussion on the arrangement of the resistors across the potential divider
The output voltage required guides on the arrangement of the resistors across the
potential divider. From the resistor values given on the potential divider and the required value
of output voltage for a given input voltage, equation Vout = Vin R2/(R1+R2) is used to locate the
resistors to give the required output voltage.

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Results
0 20 40 60 80 100 120
0
5
10
15
20
25
30
35
Frequency response
Frequency
Hight output - mm
Figure 2
The figure above shows how the pen of the signal generator deflects with change in the
frequency of the input signal at a constant input voltage.
0 500 1000 1500 2000 2500 3000 3500 4000
0
5
10
15
20
25
30
35
40
Hight Output
Amptitude
Hight output
Figure 3
The figure shows how the pen of the signal generator changes with change in the input voltage
at a constant signal frequency.

Performance of electrocardiogram 5
Calculations
Gradient of the linearity graph
Gradient= Change∈ y
Change∈ x = 36−2
3500−260 = 0.01cm/mV.
This means that the sensitivity of the signal generator pen is of 0.01 cm for each change in 1
mV of input voltage.
The cut-off frequency= 30
Cut-off frequency is the system frequency boundary of a frequency response system whereby
there is a visible reduction in the energy flowing through the system (Dunlop, 2017). This is
achieved by setting the input voltage of the signal generator to a given value that coincides
with the required output cut-off frequency. This means that it is at the frequency of 30 where
the frequency response falls to a value of 71% of its low frequency value.
Discussion
The linearity graph line gradient does not agree with the sensitivity setting of 1cm/mV
used because the gradient of the line has been found to be 0.01cm/mV. From the frequency
response graph, it is clear that the type of filter is the low pass filter. A low pass filter only
allows the passage of signals below a given cut-off frequency while attenuating the signals
with a higher frequency (Tohidian, Madadi, Staszewski, 2014) as it is in this case. In this
case, the filter has attenuated all the frequencies above 30Hz and therefore from definition,
30Hz is the cut-off frequency. The ECG recorder has included a filter because it is performing
the 12-Lead electrocardiogram which requires high fidelity meaning only the cardiac rhythm
is required (Loreto et al, 2016). The low pass filter therefore helps to remove the unwanted
high frequency signals from the external noise and muscle artifacts so as to guarantee the

Performance of electrocardiogram 6
fidelity of the process (Asl et al, 2018). This plays a very crucial role in the analysis of the
required signals because all the unwanted signals that are not within the required range are
eliminated leaving only the signals that are required and crucial in the analysis to give the
appropriate and uncontaminated signals hence guarantees efficiency and effectiveness of the
results obtained.

Performance of electrocardiogram 7
References
Asl, M.E., Rahimpour, M., Merati, M.R., Panahi, A.H. and Gholami, K., 2018. Pre-Hospital
Management of Acute Myocardial Infarction Using Tele-Electrocardiography System. arXiv
preprint arXiv:1805.05913.
Dunlop, J., 2017. Telecommunications engineering, 4(6), pp.739-753. Routledge.
Johnson, K.W., Brush IV, E.V. and McTigue, M.T., Keysight Technologies Inc,
2016. Oscilloscope system and method for simultaneously displaying zoomed-in and zoomed-out
waveforms. U.S. Patent 9,459,290.
Management of Acute Myocardial Infarction Using Tele-Electrocardiography System. arXiv
preprint arXiv:1805.05913.
Rodriguez, A.P., 2017. The Electrocardiogram. In Cardiology Procedures (pp. 157-162).
Springer, London.
Tohidian, M., Madadi, I. and Staszewski, R.B., 2014. Analysis and design of a high-order
discrete-time passive IIR low-pass filter. IEEE Journal of Solid-State Circuits, 49(11), pp.2575-
2587.