## 3 Results and Discussion
This suggests that high HRV could lead to a lower LF/HF ratio, and the subject might have an undiagnosed heart condition or arrhythmia, though no conclusion can be made. For recordings no. 16,420 and 16,483, the LF/HF ratio was much higher than in the other recordings due to missing R peaks, which caused incorrect higher RR intervals. The estimated normalized HF power was very low, while the LF power was higher. The spectrograms showed high-magnitude events in the HF region that spread into the LF range, leading to a higher LF/HF ratio [46; 47]. The estimated power values for the Arrhythmia dataset are shown in Table 5. In most cases, the normalized LF power is lower than the normalized HF power, indicating better activity in the HF range compared to LF. Except for six recordings, most LF/HF ratios were lower than one, and the ratios in the Arrhythmia dataset were generally lower than those in the normal sinus dataset. Recordings no. 106, 119, and 233 have very low LF/HF ratios, with abnormally low LF power compared to HF power. In the RR interval calculation step, large variations were observed in these recordings, which also appear as high-magnitude events in the HF range in the spectrograms (Figures 23 and 24). These variations suggest that high HRV could lead to a lower LF/HF ratio. Figure 23: CWT spectrograms of recordings no. (**a**) 106, (**b**) 119, and (**c**) 233. Figure 24: RR intervals vs. beat number plots of recordings no. (**a**) 106, (**b**) 119, and (**c**) 233. For recordings no. 112, 122, 123, 222, 230, and 231, the LF/HF ratio was higher than one, as seen in the spectrograms (Figure 19). These recordings showed high-magnitude events in both the LF and HF ranges, with the LF events being brighter than HF. These variations were reflected in the RR interval plots and confirmed during power estimation, where the LF/HF ratio was higher than one, deviating from the other recordings. To compare the LF/HF ratios between the Normal Sinus Rhythm and Arrhythmia datasets, scatter plots were created (Figure 25), illustrating the LF/HF ratios of both groups. Figure 25a shows the distribution of the LF/HF ratios for the normal sinus rhythm recordings, where most ratios are above one, except for recording no. 16,539, which deviated due to variations in the RR intervals. Recordings no. 16,420 and 16,483 showed higher ratios due to missing R peaks, causing incorrect high variations. Figure 25b displays the LF/HF ratios for the arrhythmia recordings, with most ratios below one, except for six recordings. Recordings no. 112 and 115 had a ratio close to one, indicating balanced parasympathetic and sympathetic nervous system activity. Anomalous recordings in both datasets were due to high variations in the RR intervals. In the Normal Sinus Rhythm dataset, recording no. 16,539 showed a low LF/HF ratio, while in the arrhythmia recordings, the high LF range power contributed to a higher LF/HF ratio. The comparison between both datasets shows that arrhythmia subjects are more likely to have a lower LF/HF ratio, indicating a dominance of the parasympathetic nervous system (PNS), while normal sinus rhythm subjects show a higher ratio, indicating sympathetic nervous system (SNS) dominance. As a future work wavelet transform could be used in the HRV analysis of patients suffering from different kinds of diseases and it could also be used to study the effect of gender and age on HRV.