Design of Multiple Bandpass Filters with Integer Coefficients for a Microcontroller Environment with an Emphiasis on Applications in Wearable Tremor Analysis

Wearable computing devices are becoming an important technology for medical diagnostic and treatment assessment. Many such devices have strict power and size requirements and are therefore often limited to small, integer- only signal processing microcontrollers. It is therefore a significant challenge to develop signal processing techniques that provide the necessary application fidelity with strict implementation limitations. One of our research projects involves the use of wearable devices to assess the efficacy of treatments for Essential Tremor and Parkinson´s Disease patients. Accelerometers are used to measure the tremor, and the resultant signal spectra are analyzed using digital bandpass filters to measure the amount of tremor in each of several frequency bands. This paper presents a design procedure for integer-only filters (suitable for microcontroller implementation) using repeated convolution and frequency shifting that is shown to produce superior filters than those designed by commercial filter design tools.