Frequency Response Deviation Research Articles

Model reduction of discrete-time systems VIA frequency response matching

An algorithmic approach to reduced order modelling of discrete-time systems is developed. It preserves the dominant eigenvalues of the original system while minimizing the frequency response deviations between the original system and the reduced model. The coefficients of numerator polynomials of the reduced order pulse transfer function matrix are obtained by utilizing a Fletcher-Powell unconstrained optimization algorithm. The proposed algorithm is illustrated by two examples.

Measurement of the swept-frequency carrier-induced FM response of a semiconductor laser using an incoherent interferometric technique

The swept frequency deviation response of a distributed feedback (DFB) laser is measured using an incoherent interferometric technique. Unlike previous interferometric techniques, this technique is independent of the phase relationship between the optical fields in the two interferometer paths. The theoretical background is discussed, and measurements yielding an FM deviation response of +or-1 dB from 0.1 to 2.9 GHz with an efficiency of approximately 300 MHz/mA are reported for a 1.55- mu m DFB laser.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis of coefficient quantization errors in state-space digital filters

In this paper, we examine the sensitivity of state-space digital filters to coefficient quantization errors. A cost function using an L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> norm criteria is used to measure the deviation in frequency response of the filter. The cost function is used to indicate the connection between roundoff noise and filter sensitivity to coefficient quantization errors. Then based on this cost function it is shown that low roundoff noise state-space digital filters, filters in balanced coordinates, and filters based on polynomials orthogonal on the unit circle have low sensitivity to coefficient quantization errors. Furthermore, the sensitivity of the filters is shown to depend on the second-order modes thereby exhibiting certain robustness and immunity to filter bandwidth.

Optimization in model reduction

Abstract Model reduction for reducing a high-order transfer function to one of low order is based on minimizing the deviations in frequency response throughout the frequency range of interest. Several examples are used to illustrate the procedure and to test the viability of such an approach to model reduction.

Sound Level Meter Performance

In the past decade, the increasing use of sound level meters in industry has fully demonstrated their value. However, with this increasing use, there has grown a more critical attitude with respect to their relative performance. A fundamental criticism, particularly in the case of noise acceptance measurements, has been the frequently observed lack of agreement among sound level meters of different manufacturers, though calibrated to the same reference level and otherwise fulfilling the performance requirements of the ASA. This paper discusses the factors responsible for this condition. Suggestions are advanced relative to the elimination of the tolerable deviations in frequency response of the standards that should aid materially in clarifying and improving the existing situation. In addition, the results of advances in the direction of improving the stability or constancy of performance of sound level meters are presented.

Sound Level Meter Performance

In the past decade, the increasing use of sound level meters in industry has fully demonstrated their value. However, with this increasing use, there has grown a more critical attitude with respect to their relative performance. A fundamental criticism, particularly in the case of acceptance measurements, has been the frequently observed lack of agreement among sound level meters of different manufacturers though calibrated to the same reference level and fulfilling the performance requirements of the A.S.A. This paper discusses the factors responsible for this condition based on experience in the development of sound level meters and their application to industrial problems. Suggestions are advanced relative to both procedures and standards that should aid materially in clarifying and improving the existing situation.