Which filter is used in ECG?
The high-pass and low-pass filters together are known as a bandpass filter, literally allowing only a certain frequency band to pass through. The notch filter is used to eliminate the line frequency and is usually printed on the ECG (e.g. ~60 Hz).
Which machines CMRR is of order of 100 120 dB?
Which machines CMRR is of order of 100-120 dB? Explanation: CMRR of the order of 100–120 dB with 5 kW unbalance in the leads is a desirable feature of ECG machines.
Which filter is present in DSP system?
What is baseline wander in ECG?
Baseline wander is a low frequency artifact in the ECG that arises from breathing, electrically charged electrodes, or subject movement and can hinder the detection of these ST changes because of the varying electrical isoline (Figure 1(a)).
What is baseline removal?
Also known as the white tophat, it removes the result of performing a morphological opening operation using a predefined structuring element from the input signal.
What causes baseline wander?
Baseline wander is a commonly seen noise in ECG recordings and can be caused by respiration, changes in electrode impedance, and motion. ... Therefore, it is vital to effectively eliminate baseline wander before any further processing of ECG such as feature extraction.
Why do we use anti-aliasing filter?
This filter is an anti-alias filter because by attenuating the higher frequencies (greater than the Nyquist frequency), it prevents the aliasing components from being sampled. Because at this stage (before the sampler and the ADC) you are still in the analog world, the anti-aliasing filter is an analog filter.
How can aliasing be reduced?
Aliasing is generally avoided by applying low pass filters or anti-aliasing filters (AAF) to the input signal before sampling and when converting a signal from a higher to a lower sampling rate.
What is meant by anti imaging filter?
From Wikipedia, the free encyclopedia. In a mixed-signal system (analog and digital), a reconstruction filter, sometimes called an anti-imaging filter, is used to construct a smooth analog signal from a digital input, as in the case of a digital to analog converter (DAC) or other sampled data output device.
Which device is needed for the reconstruction of signal?
What is imaging in DSP?
Aliasing is when a higher frequency mirrors DOWN about 1/2 the Nyquist frequency, but Imaging is when a lower frequency mirrors UP about 1/2 the Nyquist frequency. ... It has something to do with the DSP reconstruction of the signal the consequences of "zero padding" and so forth.
What is the need for anti imaging filter after upsampling a signal?
After the upsampling process, the images of the spectra of uL,s,j will appear and, therefore, an anti-imaging filter should be employed to reject those images in frequencies above π/m. In most cases, a causal filter introduces substantial phase lags.
What type of filter is an anti-aliasing filter?
Anti-aliasing filters are always analog filters as they process the signal before it is sampled. In most cases, they are also low-pass filters unless band-pass sampling techniques are used.
How do I make an anti-aliasing filter?
Anti-aliasing filters are typically designed as higher order active filters using a low-noise op-amp. The goal is to design the filter with unity gain across the pass band and to set the -3 dB cutoff frequency to be set precisely equal to the Nyquist frequency, which in turn is half your intended sampling rate.
What is decimation process?
Loosely speaking, “decimation” is the process of reducing the sampling rate. In practice, this usually implies lowpass-filtering a signal, then throwing away some of its samples. “Downsampling” is a more specific term which refers to just the process of throwing away samples, without the lowpass filtering operation.
How is downsampling done?
The idea of downsampling is remove samples from the signal, whilst maintaining its length with respect to time. For example, a time signal of 10 seconds length, with a sample rate of 1024Hz or samples per second will have 10 x 1024 or 10240 samples.
Why do we need downsampling?
Answering Jessica's question directly - one reason for downsampling is when you're working with a large dataset and facing memory limits on your computer or simply want to reduce processing time.
What is the purpose of downsampling?
(1) To make a digital audio signal smaller by lowering its sampling rate or sample size (bits per sample). Downsampling is done to decrease the bit rate when transmitting over a limited bandwidth or to convert to a more limited audio format. Contrast with upsample. See sampling.
Which is better upsampling or downsampling?
In short: Upsampling: does/should not loose information (if done wisely), then safer, Downsampling: may loose information (if done unwisely), yet more computationally efficient.
Why is decimation used?
In communications and in typical GnuRadio applications, decimation is most commonly used to reduce the sampling rate of an oversampled signal, in order to reduce the computational complexity of the system. ... The FM signal is approximately 200 KHz wide, so you sample the downconverted signal at (let's say) 512 kHz.
Does downsampling cause aliasing?
If a discrete-time signal's baseband spectral support is not limited to an interval of width 2 π / M radians, downsampling by M results in aliasing. Aliasing is the distortion that occurs when overlapping copies of the signal's spectrum are added together.
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