Comparison of HRV Indices of ECG and BCG Signals

Electrocardiography (ECG) plays a significant role in diagnosing heart-related issues, it provides, accurate, fast, and dependable insights into crucial parameters like QRS complex duration, the R-R interval, and the occurrence, amplitude, and duration of P, R, and T waves. However, utilizing ECG for prolonged monitoring poses challenges as it necessitates connecting multiple electrodes to the patient's body. This can be discomforting and disruptive, hampering the attainment of uninterrupted recordings. Ballistocardiography (BCG) emerges as a promising substitute for ECG, presenting a non-invasive technique for recording the heart's mechanical activity. BCG signals can be captured using sensors positioned beneath the bed, thereby providing enhanced comfort and convenience for long-term monitoring of the subject. In a recent study, researchers compared the heart rate variability (HRV) indices derived from simultaneously acquired ECG and BCG signals. Encouragingly, the BCG signal yielded satisfactory results similar to those obtained from ECG, implying that BCG holds potential as a viable alternative for prolonged monitoring. The findings of this study carry substantial implications for the advancement of innovative, non-invasive methods in monitoring heart health. BCG showcases the ability to offer a more comfortable and convenient alternative to ECG while retaining its capacity to deliver accurate and reliable cardiac information concerning a patient's condition.

Radar Cross Section Reduction of Microstrip Patch Antenna using Metamaterial Techniques

Radar cross section (RCS) reduction has become one of the critical research areas in recent years. The RCS of the target should be small to avoid detection. Different methods are used to reduce RCS, but the major challenge with many RCS minimization methodologies is that, it may deteriorate some antenna parameters. When antenna mode RCS is considered; structural mode RCS, and antenna parameters are critical, as the structure should be an antenna and a RCS reducing structure simultaneously. The techniques like applying Radar Absorption Material (RAM) entirely over the target, deployment of Energy Band Gap (EBG) structures, the use of passive, active cancellation, and polarization conversion are prevalent methods to reduce RCS. The manifestation of metamaterial property in an antenna results in the antenna's electromagnetic characteristics becoming negative for a particular bandwidth. Thus the RCS of the antenna can be reduced to a minimum range by loading the metamaterial structures. This paper discusses the application of polarization conversion method (PCM), L-structured and Square-structured fractal metamaterial antenna for RCS reduction. This paper reports the simulation, fabrication, and testing of the above antennas with their performance comparison. The antennas are designed for 4.3GHz frequency with a total dimension of 80mmx80mmx1.6mm. Antenna parameters like return loss, gain, radiation pattern, and bandwidth are analyzed along with the RCS. The L-structured metamaterial antenna implemented has a 29.37% larger bandwidth than the reference patch antenna with a gain of 2.94dB with a return loss of -28.28dB.

Constrained RS coding for Low Peak to Average Power Ratio in FBMC -- OQAM Systems

Multi-carrier modulation techniques have now become a standard in many communication protocols. Filter bank based multi-carrier (FBMC) generation techniques have been discussed in the literature as a means for overcoming the shortcomings of IFFT/FFT based OFDM system. The Peak to Average Power Ratio (PAPR) is a problem faced by all multi-carrier techniques. This paper discusses the methods for reducing PAPR in a FBMC system while maintaining acceptable Bit Error Rate (BER). A new PAPR minimizing scheme called Constrained Reed Solomon (CRS) coding is proposed. The hybrid techniques using coding and companding are tested for different channel models and is found to yield promising results.