Long-term ECG monitoring is desirable in many daily healthcare situations where a wearable device that can continuously record ECG signals is needed. In this work, we proposed a wearable heart rate belt for ambulant ECG monitoring which can be comfortably worn on the chest or the waist. Active textile electrodes were designed for ECG recording. And a battery powered circuit board was developed consisting of ECG signal conditioning circuits, a 3-axis accelerator for body motion detection, a 12-bit AD converter, a DSP for signal processing and a SD card for data storage. The system also includes a wireless communication module that can transmit heart rate data to a sport watch for displaying. Experiments were carried out which shows that the proposed system is unobtrusive and can be comfortably worn by the user during daily activities. When wearing on the waist, ECG signals with reasonably good quality were acquired in rest and walking situations. The proposed system shows promise for long-term ambulant ECG monitoring.

Previously we described a method of calculating auditory excitation patterns and loudness for steady sounds, based on a nonlinear filterbank. Here the method is extended to deal with time-varying sounds. Firstly, the input waveform is transformed to short-term spectrum by a structure with six FFTs, which using longer signal segments for low frequencies and shorter segments for higher frequencies. Secondly, the excitation patterns are calculated from the short-term spectrum, and the summation of the excitation gives a value for the instantaneous loudness. Thirdly, the short-term loudness is calculated from the instantaneous loudness using an averaging mechanism similar to an automatic gain control system, with attack and release times. Finally the long-term loudness is calculated from the short-term loudness using a similar averaging mechanism, but with longer attack and release time. The method gives good predictions of loudness for both steady sounds and time-varying sounds.

Spectral cues are important for speech intelligibility, but they are distorted, in most popular multi-band compression algorithms for hearing aids, by being split into multiple bands and processed by different amplifiers. The paper presents a morphology-based method, which can preserve primary spectral cues and have low computation cost. Speech testing results demonstrate its efficiency.

Among all algorithms based on wavelet transform and zerotree quantization, Said and Pearlman's (1996) set partitioning in hierarchical trees (SPIHT) algorithm is well-known for its simplicity and efficiency. This paper deals with the real-time implementation of SPIHT algorithm using DSP chip. In order to facilitate the implementation and improve the codec's performance, some relative issues are thoroughly discussed, such as the optimization of program structure to speed up the wavelet decomposition. SPIHT's high memory requirement is a major drawback for hardware implementation. In this paper, we modify the original SPIHT algorithm by presenting two new concepts-number of error bits and absolute zerotree. Consequently, the memory cost is significantly reduced. We also introduce a new method to control the coding process by number of error bits. Our experimental results show that the implementation meets common requirement of real-time video coding and is proven to be a practical and efficient DSP solution.

This paper represents a novel compression method for ultrasound images in a tele-ultrasound system. The encoder chooses the ultrasound scan line signals as the object to be compressed and transmitted other than the standard video images in conventional methods. Furthermore, nonuniform discrete wavelet transform is proposed considering the different resolutions in axial and lateral directions of ultrasound images. Experimental results show that the new method provides better compression performance than conventional methods in terms of a peak signal-to-noise ratio and processing time.