There have beem many studies on the analysis and design of low-noise oscillators. Recently, much attention has been paid to the noise reduction technique using coupled oscillators. When oscillators are coupled, the coupling method is very important and affects various factors, for example, the level of noise. In this study, we analyze the phase noise of multiphase CMOS LC oscillators coupled by mutual inductors by using the impulse sensitivity function. From the simulation results, using mutual inductors as coupling elements can reduce the phase noise. Also, for oscillators coupled by mutual inductors, we show that setting a coupling coefficient of around 0.2 can realize the lowest phase noise near the oscillation frequency.

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In this paper, the new absolute phase detection scheme (APDS) is presented. With a simple mathematical analysis, the proposed APDS algorithm is capable of accurately detecting the absolute phase without using reference phase like other conventional techniques. The other massive benefit of using the proposed APDS scheme is its range-expansion flexibility for each application depending on the selected traditional PD. Based on the proposed APDS, BPSK and QPSK demodulated simulations, accurately recovering 16-bit-information data, are implemented with the blind carrier recovery methods. Also, the analog multiplier PD was selected in order to verify the proposed QPSK demodulator under the AWGN channel. It is found that the output phase is irrelevantly disturbed by additive white Gaussian noise. For the QPSK-demodulated PSPICE simulation, the proposed technique is more compatible with the frame processing manner rather than the real time processing. From both PSPICE and Matlab simulations for BPSK and QPSK demodulation the proposed APDS scheme provides convenience, advantages, and acceptable results in comparison to other traditional techniques.

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People often have to stand waiting in a queue, which they may find disagreeable. Facilities where people must wait, for example, food courts, banks and amusement parks, need to recognize and provide an estimated wait time to increase customer satisfaction. Hence, there is demand for wait time estimation methods. Also, the requirement for estimation accuracy changes with the length of the queue. In this paper, we propose a cooperative line wait time estimation method using Bluetooth low energy (BLE, marketed as Bluetooth Smart) on a smartphone. To estimate the wait time, we utilize the stay-times of users approaching and moving past two preinstalled receivers. The wait time is estimated by the difference between the two stay-times. Our stay-time estimation includes two methods: a direct-wave blocking method and a stay-time estimation method. We experimentally evaluated with our method in a passageway of our university campus for different values of the range value which is a parameter used in the stay-time estimation. It was found that when the range value was set to 4-8 dB, almost all of the devices estimated the wait time to be within 20 s of from the expected wait time. This result satisfied the requirement of all users according to our questionnaire about discontent with erroneously estimated wait times.

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Estimates of time difference of arrival (TDoA) can be used in audio (and radio) for localization, positioning and navigation. Such estimates are typically obtained from one or several microphone (or antenna) pairs. In this paper we demonstrate that better TDoA estimates can be obtained by using sub-sample correlation. The main idea is to first obtain an initial estimate of the TDoA estimate and then refining these using a local optimization over sub-sample shifts. For a sub-sample shift one calculates the interpolated signal and evaluates the correlation criterion and the derivatives of the correlation with respect to sub-sample shifts. These are then used in an efficient implementation of determining optimal TDoA estimates using a local optimization of the correlation criterion. The method has been implemented and tested on real data, where it is demonstrated that using the improved TDoA estimates in a system for simultaneously estimating microphone and sound source positions gives better precision and lower residuals in the results.

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A method is presented for transcoding from MPEG-2 to HEVC by using picture structure information. One of the main issues in the process of transcoding from MPEG-2 to HEVC is the efficiency of HEVC encoding. For HEVC encoding, a hierarchy picture structure called a random-access mode is usually used for high efficiency coding; however, the random-access mode may not always be the best structure for transcoding from MPEG-2 to HEVC. We propose some picture structures using MPEG-2 stream information. The experimental results show that the information on the picture coding structure in the MPEG-2 video stream is useful for transcoding MPEG-2 to HEVC. The proposed method with hierarchy picture structure using the MPEG-2 structure information reduced bitrate by 7.1% in the transcoding experiments.

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This research is concerned with a dynamic mapping electrocardiogram (ECG) compression method that effectively reduces the percent root mean square difference (PRD) and at the same time achieves the satisfactorily high compression ratio (CR). The distinctive characteristic of the proposed technique lies in its applicability to both the regular and irregular ECG signals, compared to existing techniques that are solely applicable to the regular signal. Specifically, in the dynamic mapping, the Period Scaling technique is first applied and the Dynamic Time Warping (DTW) technique is then triggered if the signal error exceeds the maximum beat error. The signal error exceeding the maximum beat error indicates an irregular ECG signal. In the assessment, the proposed technique was applied to a total of 42 MIT-BIH ECG signals. The experiments were conducted using a maximum beat error of 1% and various threshold criteria sets by varying EPE_AC and EPE_DC1, EPE_DC2, EPE_DC3 in the ranges of 90-99% and 50-99%, respectively, where EPE_AC and EPE_DC1-3 are Energy Packing Efficiency's approximation coefficient and detailed coefficients. The results indicate that the threshold sets of 99% for EPE_AC and 80-90% equally for EPE_DC1, EPE_DC2 and EPE_DC3 contribute to less than 1% PRD values and the satisfactorily high CR levels of 4.6-11. Moreover, this research descriptively compared the ECG signal numbers 100 (regular), 117 and 228 (irregular) with regard to the signal compression performances.

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