This paper describes the Network Time Protocol (NTP), which is designed to distribute time information in a large, diverse internet system operating at speeds from mundane to lightwave. It uses a symmetric architecture in which a distributed subnet of time servers operating in a self-organizing, hierarchical configuration synchronizes local clocks within the subnet and to national time standards via wire, radio or calibrated atomic clock. The servers can also redistribute time information within a network via local routing algorithms and time daemons. This paper also discusses the architecture, protocol and algorithms, which were developed over several years of implementation refinement and resulted in the designation of NTP as an Internet Standard protocol. The NTP synchronization system, which has been in regular operation in the Internet for the last several years, is described along with performance data which shows that timekeeping accuracy throughout most portions of the Internet can be ordinarily maintained to within a few milliseconds, even in cases of failure or disruption of clocks, time servers or networks. Keywords: network clock synchronization, standard time distribution, fault-tolerant architecture, maximumlikelihood principles, disciplined oscillator, internet protocol.

Abstract-- In this paper, we present and discuss some circuit experiments that verify our previous claims, which were based on numerical simulations of mathematical models, that chaos can be used to broaden the capture range of the common phase-locked loop circuit.

Abstract: This paper proposes an active noise control algorithm for periodic disturbances of unknown frequency. The algorithm is appropriate for the feedback case in which a single error microphone is used. A previously-proposed algorithm for the rejection of sinusoidal noise sources is extended for the cancellation of multiple harmonics. Unlike many other approaches, the estimates of the frequencies of the separate harmonics are tied together within the algorithm to account for the integer multiplicative relations between them. The dynamic behavior of the closed-loop system is analyzed using an approximation that is shown, in simulations, to provide an accurate representation of the system's behavior. Experimental results on an active noise control testbed demonstrate the success of the method in a practical environment. 1.

The lectures aim to explain and discuss the knowledge of biology at foundation level which is essential to proceed to higher level of study in biology-related disciplines. Learning Outcomes: On successful completion of this subject, students are expected to be able to: 1. understand the basic features and functions of cells; 2. describe the basic structures and functions of body systems; 3. understand the fundamental features of microorganisms; and 4. understand the basic features of ecosystems.

This document constitutes a formal specification of the Network Time Protocol (NTP) Version 3, which is used to synchronize timekeeping among a set of distributed time servers and clients. It defines the architectures, algorithms, entities and protocols used by NTP and is intended primarily for implementors. A companion document [MIL91a] summarizes the requirements, analytical

Abstract: A novel Phase-Locked Loop scheme is proposed in this paper, whose main distinguishing features are infinite hold-in range, pull-out range fractionally constant and also a ripple fractionally constant. To this end, it incorporates a variable gain amplifer and a frequency tunable loop filter. The driving application is the on-chip automatic tuning of slave filters, although the PLL architecture can be employed in many other applications. 1.

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Abstract—We present a mathematical analysis of the common-mode instability and power back-off feature of a transformer-coupled Class-AB differential power amplifier (PA). The efficient impedance matching of the transformer combiner and efficiency improvement at power back-off, a major benefit of this structure, are illustrated. In addition, an analytical model is derived to predict the common-mode oscillations in PA. The analytical results, based on a simple hand-calculation model for the transistor, show good agreement with simulation results using complete 90-nm models. Two methods to suppress the common-mode oscillations are investigated and analyzed in detail. Index Terms—CMOS, power amplifiers (PAs), power combining, stability. I.

OF THE THESIS A 915 MHz CMOS Frequency Synthesizer by Jacob Jude Rael Master of Science in Electrical Engineering University of California, Los Angeles, 1995 Professor Asad A. Abidi, Chair A 915 MHz Frequency Synthesizer is designed and tested for use in a low power spread-spectrum communication transceiver. The synthesizer consists of a phase locked loop to control a four stage ring oscillator to output 915 MHz. The four stage ring oscillator naturally provides two sets of quadrature signals for use in a single-sideband modulator (SSB) and requires no external components. The complete Frequency Synthesizer is fabricated in a 1 m standard CMOS process and at a supply voltage of 4.2 volts, the VCO dissipates 18.8 mW. Finally, the expected noise and speed performance for other technologies is presented. 1 Chapter 1 System Considerations 1.1 Introduction The increased use of laptop computers and cellular phones in the last decade demonstrates the growing need for devices that ...

A 900-MHz direct-conversion receiver to detect a frequency-hopped carrier with frequency shift keying (FSK) modulation at 160 kb/s is integrated on the same chip as the transmitter. The receiver combines a low-noise amplifier with downconversion mixers and low-pass channel-select filters in quadrature channels. A digital correlating detector makes the data decisions. The received signal is dehopped when it is downconverted. The cascade noise figure is 8.6 dB, and the cascade IIP3 is 08.3 dBm. In active mode, the receiver takes 120 mA from 3 V. I.