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Date of Conference: 28-31 October 2007 Conference Name: Ultrasonics Symposium, IEEE 2007 In this paper, capacitive micromachined ultrasonic transducers are fabricated using a sacrificial surface micromachining process. A testing procedure has been established in order to measure the absolute transmit and receive sensitivity spectra of the fabricated devices. The experiments are performed in oil. Pulse-echo experiments are performed and the results are compared to the pitch-catch measurements using calibrated transducers.

Date of Conference: 2-6 Oct. 2006 Conference name: 2006 IEEE Ultrasonics Symposium In this paper, we present equivalent circuit for immersed capacitive micromachined ultrasonic transducers (cMUT), based on an accurate parametric model. We also present an accurate approximation for the radiation impedance cMUT. We develop a design approach for immersed cMUTs using the equivalent circuit. We demonstrate that the equivalent circuit predicts the performance of a cMUT array element composed of many cells in parallel. We investigate the applicability of the equivalent circuit in designing cMUT array elements. © 2006 IEEE.

Date of Conference: 9-13 Oct. 2006 Conference Name:The Second IEEE International Conference on Technologies for Homeland Security and Safety (TEHOSS 2006) In this work, a complete design of PMR (Professional Mobile Radio) network based on CDMA 450 in ˙Istanbul metropolitan region is presented. Coverage and capacity analysis are performed by the developed simulation software tool. Trade off between several system parameters such as quality of service, user mobility, traffic distribution, data rate and bandwidth are considered to optimize the capacity and coverage of the network. Coverage and handoff areas are shown on the map by the aid of GIS (Geographical Information Systems) tool. System capacity and coverage are presented as the main results of the proposed network.

Chapter 3 Computerized electrocardiogram (ECG), electroencephalogram (EEG), and magnetoencephalogram (MEG) processing systems have been widely used in clinical practice [1] and they are capable of recording and processing long records of biomedical signals. The use of such systems (1) enables the construction of large signal databases for subsequent evaluation and comparison, (2) makes the transmission of biomedical information feasible over telecommunication networks in real time or off line, and (3) increases the capabilities of ambulatory recording systems such as the Holter recorders for ECG signals. In spite of the great advances in VLSI memory technology, the amount of data generated by digital systems may become excessive quickly. For example, a Holter recorder needs more than 200 Mbits/day of memory space to store a dual-channel ECG signal sampled at a rate of 200 samples/sec with 10 bit/sample resolution. Since the recorded data samples are correlated with each other, there is an inherent redundancy in most biomedical signals. This can be exploited by the use of data compression techniques which have been successfully utilized in speech, image, and video signals [2] as well.

Date of Conference: 2-6 October 2006 Conference Name: Ultrasonics Symposium, IEEE 2006 We present a new method to calculate the transformer ratio of a cMUT in Mason's Equivalent circuit model. The effect of the spring softening capacitance is also included in the analysis. We use the existing turns ratio calculation methods as a starting point to calculate the force-voltage ratio at the secondary of the transformer and the input port of the circuit. We use this ratio and the capacitances in the Mason's circuit to find the actual turns ratio. Different methods are discussed for the calculation of the equivalent circuit parameters. We show that the transformer ratio has a bounded maximum at collapse voltage. We also investigate the effect of electrode size on the transformer ratio. Transformer ratio decreases with decreasing electrode size.

Date of Conference:Sept. 2000 Conference Name:Int. Workshop on Direct and Inverse Wave Scattering

Date of Conference: Sept. 2000 Conference Name:Proc. of IEEE 50th Annual Broadcast Symposium The problem of efficient utilization of the radiofrequency spectrum is becoming more complex due to the increasing demands on the spectrum, which is a limited natural resource. If this natural resource is to be used efficiently, administrations need to use advanced Automated Spectrum Management Systems (ASMS) which would facilitate national spectrum management and monitoring, coordination among administrations and notification to International Telecommunication Union (ITU). This paper presents some of the spectrum engineering analysis and planning tools of the National Frequency Management System (NFMS) as part of the ASMS which has been developed for the administration of Turkey. This system includes a Relational Database Management System (RDBMS) to support a database containing frequency assignment data, licence holder data and equipment characteristics data. The software is integratedwith a Geographic Information System (GIS) and it has the capability of using digital terrain data and geographic data

Conference Name:IEEE APS International Symposium and USNC/URSI National Radio Science Meeting Date of Conference:July 2000

Date of Conference:June 2000 Conference Name:Proc. of 10th Virginia Tech Symposium on Wireless Personal Communications

Date of Conference: 31 Ocober-3 November 1993 Conference Name: 1993 IEEE Ultrasonics Symposium Phase aberration correction based on time delay estimation via minimization of sum of absolute difference (SAD) between radio frequency (RF) signals of neighboring elements is studied in the presence of missing elements. To examine the influence of inactive elements, phase estimation error is measured for various combinations of different number of missing elements, aberration level, and SNR. The measurements are performed on an experimental RF data set. Aberration delays of missing elements are interpolated using the phase estimate between the nearest active elements. The B-scan images are reconstructed for qualitative examination.

In this paper, SNR maximization in coded diverging waves is studied, and experimental verification of the results is presented. Complementary Golay sequences and binary phase shift keying modulation are used to code the transmitted signal. The SNR in speckle and pin targets is maximized with respect to chip signal length. The maximum SNR is obtained in diverging wave transmission when the chip signal is as short a duration as the array permits. We determined the optimum diverging wave profile to confine the transmitted ultrasound energy in the imaging sector. The optimized profile also contributes to the SNR maximization. The SNR performances of the optimized coded diverging wave and conventional single-focused phased array imaging are compared on a single frame basis. The SNR of the optimized coded diverging wave is higher than that of the conventional single-focused phased array imaging at all depths and regions.