## 4 Importance of Electrode Configurations for FECG Measurement  
### Electrode Configurations  
Table 1 shows the comparison of electrode placement configurations over the maternal abdomen to monitor the FECG non-invasively. Comparisons have been made based on the number of electrodes placed on the maternal abdomen, and the filter parameter design used for pre-processing, such as bandwidth (BW), sampling frequency (Fs), resolution (R) of the A/D converter, and the gain (G). Figure 9: The proposed 4-stage fetal heart rate (FHR) extraction method [7]. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Author**} & \multirow{2}{*}{**Number of Electrodes**} & \multirow{2}{*}{**Parameters’ Specification**} & \multirow{2}{*}{**Participants and Time of Data Recording (s)**} & \multirow{2}{*}{**Accuracy**} & \multirow{2}{*}{**Number of Gestation**} & \multirow{2}{*}{**Proposed Method for Extraction of FECG**} \\  & & & & & & & & \\ \hline \multirow{2}{*}{1.} & [PERSON] et al., 2005 [81] & \multirow{2}{*}{3} & Equilateral triangle formation of three electrodes on the abdomen of pregnant women. & \multirow{2}{*}{N/A} & Participants = 100 & \multirow{2}{*}{**Accuracy**} & Success rates for detecting the P, QRS, and T waves \\  & & & & Recording = & were 4.6\%, 91.0\%, & & 11 st and 2 nd \\ \hline \multirow{2}{*}{2.} & [PERSON] et al., 1986 [82] & \multirow{2}{*}{4} & \multirow{2}{*}{Bandwidth = 0.2 to 120 Hz} & \multirow{2}{*}{Participants = 37 weeks} & \multirow{2}{*}{-} & Between 20 and 37 weeks & \\  & & & & & & \\ \hline \multirow{2}{*}{3.} & [PERSON] & \multirow{2}{*}{4} & \multirow{2}{*}{Sampling Frequency = 256 Hz} & \multirow{2}{*}{Participants = 30 Recording = 60 s} & \multirow{2}{*}{-} & Between 36 and 38 weeks & Peak detection \\  & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of different electrode placement for FECG monitoring. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{No.} & \multirow{2}{*}{Author} & \multicolumn{2}{c}{Number of} & \multirow{2}{*}{**Electrodes**} & \multirow{2}{*}{**Electrodes Placement**} & \multirow{2}{*}{**Parameters’ Specification**} & \multicolumn{2}{c}{**Number of**} & \multirow{2}{*}{**Accuracy**} & \multicolumn{2}{c}{**Number of**} & \multirow{2}{*}{**Proposed Method**} \\  & & & & & & & **Time of Data** & & **Precision of Precision** & **\# FECG** \\ \hline \multirow{4}{*}{4} & \multirow{4}{*}{Karvounis} & \multirow{4}{*}{4} & \multirow{4}{*}{Sampling Frequency = 300 Hz Resolution = 12 bits Gain = 7800} & Two scenarios were used: 8 Participants and 8 Participants of 60 s was performed: 97.4\% & \multirow{4}{*}{20-41 weeks} & \multirow{4}{*}{3-stage method: time frequency analysis, complex wavelet, and} & \multirow{4}{*}{97.4\%} & \multirow{4}{*}{20-41 weeks} & \multirow{4}{*}{3-stage method: time frequency analysis, complex wavelet, and} & \multirow{4}{*}{97.4\%} \\  & & & & & & & & Heuristic \\ \cline{1-1} \cline{5-10}  & & & & & 15 min each was performed. & & & algorithm \\ \hline \multirow{4}{*}{5} & \multirow{4}{*}{[PERSON] [15].} & \multirow{4}{*}{4} & \multirow{4}{*}{N/A} & \multirow{4}{*}{N/A} & \multirow{4}{*}{60\%} & \multirow{4}{*}{34 weeks} & \multirow{4}{*}{Feall heart rates (FRIS) extracted from fetal chronologically (FCCG)} \\  & & & & & & & & \\ \cline{