فشرده‌سازی سیگنال‌های صوتی قلب (PCG) مبتنی بر نمونه‌کاهی و دوبعدی‌سازی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه صنعتی شاهرود

2 گروه الکترونیک- دانشکده برق و رباتیک - دانشگاه صنعتی شاهرود

چکیده

در این مقاله یک روش فشرده‌سازی بااتلاف با قابلیت کنترل نسبی کیفیت سیگنال بازسازی شده برای سیگنال‌ صوتی قلب یا فونوکاردیوگرام (PCG) پیشنهاد شده است که مبتنی بر دو ایده‌ مهم یکی نمونه‌کاهی و دیگری دوبعدی‌سازی و تشکیل تصویر PCG است. در فشرده‌سازی تصویر PCG از تبدیل موجک و یک کدگذار ماتریس ضرایب موجک به نام «موجک درخت فضاگرا» (STW) استفاده شده است. در روش پیشنهادی، قابلیت نسبی کنترل کیفیت سیگنال بازسازی شده به کمک یک آستانه از جنس معیار ارزیابی «ریشه درصدی میانگین مجذور تفاضلات» (PRD) وجود دارد. نتایج شبیه‌سازی روش پیشنهادی روی چند پایگاه داده قابل دسترس برای همگان نشان می‌دهد که مرحله‌ نمونه‌کاهی سهم زیادی در افزایش میزان فشرده‌سازی به ویژه در مورد پایگاه‌های داده با فرکانس نمونه‌برداری بالا دارد. عامل مهم بعدی در بهبود کارایی فشرده‌سازی روش پیشنهادی، استفاده از دوبعدی‌سازی سیگنال PCG به منظور استفاده از تزایدهای بین دوره‌ای موجود در این نوع سیگنال‌های تکرارشونده، و استفاده از روش‌های موثر امروزی برای فشرده‌سازی تصویر است.  کارایی روش پیشنهادی بر طبق معیارهای متوسط PRD و متوسط «نسبت فشرده‌سازی» (CR) ارزیابی و با نتایج چند روش موجود مقایسه شده است. در این ارزیابی، به ازاء مقدار تقریبی PRD≤5% پایین‌ترین مقدار متوسط میزان فشرده‌سازی مربوط به دسته آرتیفکت از پایگاه داده‌ پاسکال (با فرکانس نمونه‌برداری 2000 هرتز) و بیشترین مقدار متوسط میزان فشرده‌سازی مربوط به پایگاه داده‌ دانشگاه واشنگتن (با فرکانس نمونه‌برداری 44100 هرتز) حاصل شده است.

کلیدواژه‌ها


عنوان مقاله [English]

Heart Sound (PCG) Signal Compression based on Down-sampling and two-dimensionalization

نویسندگان [English]

  • Salimeh Moradi 1
  • Hadi Grailu 2
1 Shahrood University of Technology
2 Department of Electrical and Robotics Engineering, Shahrood, Iran
چکیده [English]

In this paper, a lossy compression method with the ability to control the quality of the reconstructed signal is proposed for phonocardiography (PCG) signals. It is based on two main ideas: down-sampling and two-dimensionalization. For PCG image compression, wavelet transform and Spatial-oriented Tree Wavelet (STW) encoder are used. In the proposed method, there is the ability to control the quality of the reconstructed signal using a Percent Root-mean-square Difference (PRD)-related threshold. The simulation results of the proposed method on some public databases indicates that the down-sampling stage has a significant effect on increasing the compression ratio especially in the case of databases with high sampling frequency. The next important factor in improving the compression efficiency of the proposed method is the use of two-dimensional PCG signal in order to take advantage of the inter-period redundancy in this type of repetitive signals, and using modern effective methods for image compression. The efficiency of the proposed method was evaluated according to the average PRD and Compression Ratio (CR) criteria and compared with the results of several existing methods. In this evaluation, while limiting PRD≤5%, the lowest average compression ratio was related to the Artifacts dataset from the Pascal database (with a sampling frequency of 2000 Hz) and the highest average compression ratio was related to the database of the University of Washington (with a sampling frequency of 44100 Hz).

کلیدواژه‌ها [English]

  • Heart sound (PCG)
  • Signal Compression
  • Down-sampling
  • PCG Segmentation
  • Quality Control
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