Saadat Dena 650, User Manual

Page: 31 / 101

Chapter 2: System settings
20
NOTE

After setting On the EMG filter, wait a few seconds before recording.

Refer to the Troubleshooting and Error messages chapter to eliminate ECG signal noise.

If the drift filter is inactive and the signals have offset, the signals may not be flush with the
corresponding labels and the paper space may not be partitioned correctly.

For LowPass filters, -3dB cut-off frequencies are at 150 ± 20 Hz, 75 ± 5 Hz, 35 ± 2 Hz and 25 ±
2 Hz, respectively.

For Drift filter, -3dB cut-off frequency is at 0.5 ±0.1 Hz. If the drift filter is switched off, the
cuto-ff frequency will be about 0.05Hz.

The 0.5 Hz filter is used to remove signal baseline oscillations and may interfere with the ST
Segment analysis.

ECG signal saturation occurs when the signal is not displayed or exceeds lower or upper limits
of the display area.

For EMG filter, -3dB cut-off frequency increases to about 55Hz in areas where the signal slope
is high and decreases to about 10Hz when the signal slope is low.
WARNING

The use of 25, 35, and 75 Hz LowPass filters may reduce the amplitude of the cardiac signal
and omit some useful signal details.

If you turn on the HUM filter, in proportion to the selected frequency, its third harmonic will
also be removed. In other words, if the local power frequency is 50 Hz, in addition to the 50 Hz
frequency, the frequency of 150 HZ is also removed. If the power frequency of the local power
is 60 Hz, in addition to the frequency of 60 Hz, the frequency of 180 is also removed. The reason
for this is to make the heart signal clearer and smoother.

If the EMG filter is turned on, only 75 or 150 Hz options for the low-pass filter are available.
Because if the EMG filters and the 25 or 35 Hz low-pass filters are On at the same time,
significant changes will be observed on the signal amplitude.

The EMG filter is an adaptive, non-linear and time- variant filter that is applied to ECG signals.
Since EMG is a non-linear filter, the user should be trained by a qualified person to use this
filter. In some cases, using the EMG filter may affect P, QRS and T waves.