Lifting Wavelet Transformation based blind watermarking technique of Photoplethysmographic signals in wireless telecardiology

The last decade has witnessed an ample amount of research work in tele-monitoring that involves transmission of biomedicai signals through wireless media. Exchange of bio-signals amongst various hospitals and diagnostic centres requires high level of security and reliability while transmitting through internet. Watermarking is added "ownership" information in multimedia content to prove authenticity, verify signal integrity, and achieve control over the copy process. The Photoplethysmography (PPG) is a very sensitive and significant diagnostic tool in the medical world to analyse the functions of the human heart. This analysis is done in a simple manner than the most common way of using electrocardiography to detect various cardio-vascular diseases by measuring the electrical activity of the heart. The variance in its characteristics also provides important information about cardiac diseases incorporated with the same cause and raises alarm about heart malfunctioning. The present work proposes a Lifting Wavelet Transformation based method of binary watermark embedding within the Photoplethysmographic (PPG) signal as well as the process of extracting watermark from the PPG signal. In this approach, the generated watermarked signal having an acceptable level of imperceptibility and distortion is compared to the original PPG signal. Finally, a comparative study of Pulse Transit Time (PTT), pulse transit time to the foot of the pulse (PTTf) and Pulse amplitude (AMP) between the recovered PPG signal and different levels of wavelet based de-noised recovered PPG signal is done. Telecardiology is achieved by successful transmission of the watermarked PPG signal with reversibility of watermark to avoid discrepancies in data to deliver precise treatment.