Milan Stork

New fractional phase-locked loop frequency synthesizer using a sigma-delta modulator

The fractional frequency synthesizer is similar to the divide-by-N phase-locked loop (PLL) (divider in feedback path). However, the output frequency of the voltage-controlled oscillator (VCO) is not restricted to only integral multiples of the reference signal. Rather, it can also be locked to the fractional multiples, with the result of a substantial reduction of the frequency tuning step in the useful bandwidth of the PLL without reduction of its pass band. Consequently, these frequency synthesizers have both high frequency resolution and short settling time, two essential requirements for modern applications, for example, in modern radio sets. The major difficulties are spurious signals generated in the fractional divider system. The new fractional PLL frequency synthesizer with /spl Sigma//spl Delta/ modulator is described. A complete fractional PLL was simulated and partly constructed and measured.

On state-space energy based generalization of Brayton-Moser topological approach to electrical network decomposition

This paper deals with generalization of the Brayton–Moser network decomposition and related structural properties to a relatively large class of finite dimensional strictly causal systems, which can be described in the state-space representation form. The resulting energy-metric function is defined for dissipative systems and is induced by the output signal dissipation power. It is demonstrated that such a power-oriented approach determines both, the structure of a system representation as well as the corresponding system state space topology. A special form of physically correct internal structure of an equivalent state space representation has been derived as a natural consequence of strict causality, the state-space energy conservation, dissipativity assumption and the state minimality requirement.

Cuff Pressure Pulse Waveforms: Their Current and Prospective Applications in Biomedical Instrumentation

Use of the arterial pulse in the evaluation of disease states has a long history. Examination of the arterial pulse is recorded by historians as being an essential part of ancient Chinese, Indian, and Greek medicine. Palpation of the pulse was very much a part of the “art” of medicine with a bewildering array of terminologies. The first accurate recording of the arterial pulse in man was performed by Etienne Jules Marey in the nineteenth century. Marey (Marey, 1881) developed a series of mechanical devices used to noninvasively record the radial pulse in humans for physiological and clinical studies. His device for the recording the peripheral arterial pulse, the sphygmogram, was soon taken up by leading clinicians of the day, who considered the contours of the arterial pulse waveform to be important for diagnosing clinical hypertension. Interest developed in detecting the onset of hypertension in asymptomatic individuals. The principal means of doing this in the late nineteenth century was using a variety of types of sphygmographs to record the arterial pulse in a wide range of asymptomatic individuals. For the first time in history, the range of contours of the human arterial pulse was recorded and interpreted. In 1886, Marey placed the forearm and hand in a water-filled chamber to which a variable counter-pressure was applied. The counter-pressure for maximum pulse wave amplitude detected in the chamber determined that the vessel walls were maximally relieved of tension at that counter-pressure. When counter pressure was increased or decreased, the amplitudes of pulsations in the chamber decreased. This process was called vascular unloading. In the early twentieth century the Italian physician Riva-Rocci invented the cuff sphygmograph (Riva-Rocci, 1896). Riva-Rocci used palpation to determine the systolic pressure. The cuff sphygmograph was later improved by the use of Korotkoff sounds that were discovered by Korotkov (Korotkov, 1956). The use of Korotkoff sounds made the sphygmomanometer much simpler to use and allowed the clinician to base diagnosis and treatment on just two numbers, the systolic and diastolic pressures, rather than requiring the rigors of arterial waveform interpretation. The cuff sphygmomanometer was rapidly introduced into clinical practice and replaced the sphygmogram as part of the evaluation of

Digital building block for frequency synthesizer and fractional phase locked loops

The paper describes a new architecture of a digital building block, which can be used in frequency synthesizers and phase locked loops. The circuit is based on generators, counters and a register. The technique described here is much simpler then other methods. The presented synthesizer is the most suitable for the design of VLSI architectures or for programmable large scale integration (or in-system programmable large scale integration). One of the main advantages is stability and pure digital structure. On the other hand, this synthesizer has a disadvantage in its low output frequency, but this can be overcome by using it together with a phase locked loop.

Wireless electronic systems for physiological parameters measuring

Wireless communication technologies together with physiological signals sensing provide a wide range of capabilities for monitoring, recording and analysis of the physical and health status of individuals. This paper describes two systems using wireless transmission of information designed to measure physiological signals. The first system is system for automatic cardiopulmonary examination measuring and evaluating. The system measures heart rate, pulmonary ventilation, breathing frequency and blood pressure. From these data, many of other standard parameters are calculated. Application of this system is possible in work medicine, sport medicine and rehabilitation. The second system is a system for measuring and wireless transmission of selected physiological signals and variables. The system consists of wireless sensors, data transceivers and information system for the visualization and analysis of measurement data. This paper describes sensor for monitoring of body temperature and RF transceiver, which are being developed as part of the system. Temperature sensor is due to its high demand on low energy consumption not suitable for measuring signals, which will produce large amount of data and therefore consumes more energy on wireless transmission and processing of the data. Due to this reason, this sensor does not measure other signals and measure only temperature so fare. Other sensors, which will measure more physiological signals, like pulse rate, ECG and motion activity of monitored person will be developed in future. Possible use of the sensor or whole system is in a medical environment.

Fractional phase-locked loop frequency synthesizer

The fractional frequency synthesizer is similar to the divide-by-N phase-locked loop (PLL) (divider in feedback path). However, the output frequency of the voltage-controlled oscillator (VCO) is not restricted to integral multiples of the reference signal only. Rather, it can also be locked to the fractional multiples, with the result of a substantial reduction of the frequency tuning step in the useful bandwidth of the PLL without reduction of its pass band. Consequently, these frequency synthesizers have both high frequency resolution and short settling time, two essential requirements for modern applications, for example, in modern radio sets. The major difficulties are spurious signals generated in fractional divider system. In this paper, the new fractional PLL frequency synthesizer with Σ-Δ modulator is described. A complete fractional PLL was simulated, constructed and measured.

Digital chaotic systems examples and application for data transmission

A number of methods have been proposed for synchronizing chaotic systems. The most widely used methods are continuous synchronization schemes. In a continuous synchronization scheme, chaotic systems are coupled to each other continuously such that synchronization errors converge to zero. In this paper, chaos synchronization in coupled discrete-time dynamical systems is presented. Especially, practical impulsive synchronization scheme for 3 discrete time chaotic systems is shown. Simulation results finally demonstrate the effectiveness of the method. Experimental results show that chaotic and hyperchaotic systems can be synchronized by impulses sampled from one or two state variables. The impulsive synchronization can be applied to almost all chaotic and hyperchaotic systems even in the case when continuous synchronization systems fail to work. The example of data transmission based on simple discrete-time chaotic systems is also presented.

Wavelet and Hilbert-Huang transform used in cardiology

A pacemaker is a small electronic device implanted under the skin near the collarbone. Pacemakers monitor the hearts electrical activity. If the heart is beating too slowly or pausing too long between beats, the pacemaker will provide electrical impulses that stimulate the heart to beat. The pacemaker itself consists of a small box (the pulse generator) and one to three leads that are placed in the heart. This paper shortly describe electronic evaluating system which enables to find (in coordination with physician) an optimal pacemaker electrical impulses, e.g. pulse width, amplitude, delay and lead (or leads) position in heart to reducing the delivered energy. Inputs to electronic evaluating system are taken from ECG (electro cardio graph). This paper is mainly devoted to signal processing, based on wavelets analysis and Hilbert-Huang transformation (HHT) which enables to find hidden pacemaker electrical impulses in ECG (electro cardio graph signal) and evaluation of quantitative seismocardiography (QSCG). Results will be helpful for prolonging pacemaker battery life and reducing the stimuli pain on patients with implantable pacemaker and also for QSCG signal evaluation.

Cuff width alters the amplitude envelope of wrist cuff pressure pulse waveforms

The accuracy of noninvasive blood pressure (BP) measurement with any method is affected by cuff width. Measurement with a too narrow cuff overestimates BP and measurement with a too wide cuff underestimates BP. Automatic wrist cuff BP monitors use permanently attached narrow cuffs with bladders about 6 cm wide. Such narrow cuffs should result in under-cuffing for wrist circumferences larger than 15 cm. The objective of this qualitative study was to show that a narrow wrist cuff results in increased BP values when a cuff pulse amplitude ratio algorithm is used. According to the algorithm used in this study, systolic pressure (SBP) corresponds to the point of 50% of maximal amplitude; for diastolic pressure (DBP) the ratio is 70%. Data were acquired from 12 volunteers in the sitting position. The mean wrist circumference was 18 cm. The acquired cuff pulse data were used to compute SBP, mean pressure (MAP) and DBP. The mean values for a 6 cm cuff were SBP = 144 mmHg, MAP = 104 mmHg and DBP = 88 mmHg. The values for a 10 cm cuff were SBP = 128 mmHg, MAP = 93 mmHg and DBP = 78 mmHg. The reference BP values were SBP = 132 mmHg, MAP = 96 mmHg and DBP = 80 mmHg. All narrow (6 cm) cuff BP values were higher than wide (10 cm) cuff or reference BP values. The results indicate that wider wrist cuffs may be desirable for more accurate and reliable BP measurement with wrist monitors.

Physical correctness of system representations based on generalized Tellegen principle

The paper deals with a new problem of physical correctness detection in the area of strictly causal system representations. The proposed approach to the problem solution is based on generalization of Tellegens theorem well known from electrical engineering. Consequently, mathematically as well as physically correct results are obtained. The contribution is mainly concerned with presentation of a new structural approach to analysis and synthesis of linear and non-linear causal systems. It has been proven that complete analysis of instability, conservativity, dissipativity, anti-dissipativity, stability, asymptotic stability and chaoticity reduces to two independent tests: the monotonicity test of abstract state space energy and that of complete state observability, evtl. of its dual, i.e. complete state controllability property.