Fir notch filter design: a review

Notch filters are invariably used in communication, control, instrumentation and bio-medical engineering, besides a host of other fields, to eliminate noise and power line interferences. Digital notch filters can be designed as infinite impulse response (IIR) as well as finite impulse response (FIR) structures. As compared to the latter, IIR filters have the advantage that they require lower orders for efficient approximation of a given set of specifications. However, IIR filters are potentially unstable and do not provide linear phase characteristics, in general. FIR filters, on the other hand, are unconditionally stable and can be designed to give exact linear phase characteristics. We, in this review paper, focus our attention to the recent design techniques proposed by us for FIR notch filters. Standard FIR filter design methods, such as windowing, frequency sampling and computer-aided/optimization may be used for designing FIR notch filters. However, most of these methods result in ripples in the passbands. In many situations, maximally at (MF) filters are preferred since they have maximum attenuation in the stopband and hence can yield the best signal-to-noise ratio. A number of methods are available in the literature for designing MF digital filters. We, in this paper, review the design techniques for computing the weights of MF FIR notch filters. A number of design methodologies have been highlighted that lead to either recursive or explicit formulas for the computation of weights of FIR notch filters. Procedures for the design of FIR notch filters with maximal flatness of the amplitude response (in the Butterworth sense) at ω = 0 and ω = p have been given. Empirical formulas for finding the filter length N have also been proposed. By relaxing the linear phase property, it is possible to reduce the filter order required for a given magnitude response specifications. An FIR filter (with non-linear phase) can be derived from a second order IIR notch filter prototype. Explicit mathematical formulas for computing the weights for such FIR notch filters have been given. Design approaches based on the use of (i) Bernstein polynomials, and (ii) lowpass filter design have also been exploited to obtain maximally at FIR notch filters

Hysteretic control of grid-side current for a single-phase LCL grid-connected voltage source converter

© 2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/This paper proposes a new approach to control the grid-side current of LCL-grid connected voltage source converters using hysteretic relay feedback controllers. The closed loop system is stabilized by designing a local feedback around the relay element. The compensator allows the use of relay feedback controllers by making the controlled plant almost strictly positive real. The article proposes the use of the locus of the perturbed relay system as analysis and design tool and studies orbital stability for several plant and controller conditions. The approach is validated by means of simulation testing.Postprint (author's final draft

NASA micromin computer Monthly progress letter, Jan. 1967

Microminiature circuit development for flight control computer

Master of Science

thesisThis research work presents a novel way of realizing an adaptive noise canceler as a notch filter completely in the analog domain. The obvious advantage of using an adaptive notch filter would be the capability of tracking the exact frequency of interference as well as the ability to control the width of the null. The device will hereafter be referred to as the carrier canceler, as it will be used to track and cancel a 54.1 MHz carrier used in the Telescope Array RAdar (TARA) project, in southern Utah, for the detection of cosmic rays. The carrier canceler operates on a dual 5V power supply. The circuit has two inputs: An input from a signal generator that feeds a clean 54.1 MHz carrier reference and the second input, which is fed from the antenna at the receiver station of the TARA project. The circuit consists of a two tap Least Mean Square adaptive circuit that tracks the carrier frequency and phase to generate a clean replica of the carrier. This replica is then subtracted from the received signal to remove the carrier from it. The circuit is first tested in controlled conditions in the laboratory and then tested in the field. The results show the circuit has a null depth of 45 dB or better and has a 3 dB bandwidth of 300 Hz. Implementation issues such as DC offset of the multiplier Integrated Circuit (IC) and phase shift of all the ICs are discussed and a solution to rectify them is proposed

UWB Technology

Ultra Wide Band (UWB) technology has attracted increasing interest and there is a growing demand for UWB for several applications and scenarios. The unlicensed use of the UWB spectrum has been regulated by the Federal Communications Commission (FCC) since the early 2000s. The main concern in designing UWB circuits is to consider the assigned bandwidth and the low power permitted for transmission. This makes UWB circuit design a challenging mission in today's community. Various circuit designs and system implementations are published in this book to give the reader a glimpse of the state-of-the-art examples in this field. The book starts at the circuit level design of major UWB elements such as filters, antennas, and amplifiers; and ends with the complete system implementation using such modules

Development of an automatic system to monitor the performance of a dense medium (mineral) separation process

Includes bibliographical references.Dense Medium Separation (DMS) is a process used extensively in the minerals processing industry to separate dense from less dense material in a dense fluid. It may be considered to be a simple “sink-float” separation process. DMS is used on a large scale in South African coal, iron ore and diamond operations. There are, however, no commercially available systems that can determine the separation efficiency of a DMS process on-line. This presents severe problems to those operating DMS processes. The present study attempts to provide a measurement technique for on-line application

Some NASA contributions to human factors engineering: A survey

This survey presents the NASA contributions to the state of the art of human factors engineering, and indicates that these contributions have a variety of applications to nonaerospace activities. Emphasis is placed on contributions relative to man's sensory, motor, decisionmaking, and cognitive behavior and on applications that advance human factors technology

A general purpose stabilised balloon platform

The development of a three axis stabilized balloon platform capable of being operated in three modes of increasing accuracy is discussed. The system relies on angular motion sensing for primary feedback with linear accelerometers, magnetometers, and a star sensor for positional information. When under primary control the system will acquire and stabilize on any accessible part of the celestial sphere. A video verification system is included to provide pointing confirmation. Under improved accuracy control, the star sensor is used to lock onto a target star

SPS pilot signal design and power transponder analysis, volume 2, phase 3

The problem of pilot signal parameter optimization and the related problem of power transponder performance analysis for the Solar Power Satellite reference phase control system are addressed. Signal and interference models were established to enable specifications of the front end filters including both the notch filter and the antenna frequency response. A simulation program package was developed to be included in SOLARSIM to perform tradeoffs of system parameters based on minimizing the phase error for the pilot phase extraction. An analytical model that characterizes the overall power transponder operation was developed. From this model, the effects of different phase noise disturbance sources that contribute to phase variations at the output of the power transponders were studied and quantified. Results indicate that it is feasible to hold the antenna array phase error to less than one degree per power module for the type of disturbances modeled