Question

By using a _________ rather than a _________ the amplitude of low frequency noise as well as the low frequency components of the ECG will be reduced without affecting the QRS.

(a) High-pass filter, Band-pass filter

(b) Low-pass filter, Band-pass filter

(c) Band-pass filter, Low-pass filter

(d) Band-pass filter, High-pass filter

I had been asked this question in an international level competition.

I need to ask this question from Phonocardiography (PCG) in chapter Biomedical Recorders of Biomedical Instrumentation

Answer 1

Correct answer is (c) Band-pass filter, Low-pass filter

To explain: The maximum of the QRS energy spectrum is in the vicinity of 10 Hz, the filter is designed to have a bandwidth of about 15 Hz with a centre frequency of 10-12 Hz. By using a bandpass filter rather than a low-pass filter, the amplitude of low frequency noise as well as the low frequency components of the ECG will be reduced without affecting the QRS.