Impulse response analysis of coherent waveguide communication

2017 ◽  
Vol 10 (1) ◽  
pp. 101-113 ◽  
Author(s):  
Yanghyo Kim ◽  
Adrian Tang ◽  
Jason Cong ◽  
Mau-Chung Frank Chang ◽  
Tatsuo Itoh
Keyword(s):  
Frequency Domain ◽  
Impulse Response ◽  
Input Data ◽  
Group Delay ◽  
Propagation Constant ◽  
Response Analysis ◽  
Traditional Group ◽  
Inverse Fourier Transformation ◽  
Delay Variations ◽  
Response Method

An impulse response method is carried out to analyze waveguide's information capacity within a coherent communication system. Such capability is typically estimated according to group delay variations (seconds/bandwidth/distance) after carrier-modulated data undergoes a dispersive medium. However, traditional group delay methods often ignore non-linear effects by assuming input data stream only occupies narrow bandwidth such that a propagation constant can be linearized centered at the carrier frequency. Such a constraint can be lifted with a proposed baseband equivalent impulse response method by using frequency domain convolution and multiplication. Once the impulse response in frequency domain is secured, its time domain counterpart can be calculated based on inverse Fourier transformation. Such analysis can fully reveal data pulse's broadening and gauge its inter-symbol interference by simply convolving input data with extracted impulse response, not limited to specific frequency range or type of waveguide.

A Frequency-Domain INS/GPS Dynamic Response Method for Bridging GPS Outages

2010 ◽  
Vol 63 (4) ◽  
pp. 627-643 ◽  
Author(s):  
Mohammed El-Diasty ◽  
Spiros Pagiatakis
Keyword(s):  
Neural Network ◽  
Transfer Function ◽  
Dynamic Response ◽  
Dynamic System ◽  
Least Squares ◽  
Frequency Domain ◽  
Impulse Response ◽  
Time Domain ◽  
Response Model ◽  
Response Method

We develop a new frequency-domain dynamic response method to model integrated Inertial Navigation System (INS) and Global Positioning System (GPS) architectures and provide an accurate impulse-response-based INS-only navigation solution when GPS signals are denied (GPS outages). The input to such a dynamic system is the INS-only solution and the output is the INS/GPS integration solution; both are used to derive the transfer function of the dynamic system using Least Squares Frequency Transform (LSFT). The discrete Inverse Least Squares Frequency Transform (ILSFT) of the transfer function is applied to estimate the impulse response of the INS/GPS system in the time domain. It is shown that the long-term motion dynamics of a DQI-100 IMU/Trimble BD950 integrated system are recovered by 72%, 42%, 75%, and 40% for north and east velocities, and north and east positions respectively, when compared with the INS-only solution (prediction mode of the INS/GPS filter). A comparison between our impulse response model and the current state-of-the-art time-domain feed-forward neural network shows that the proposed frequency-dependent INS/GPS response model is superior to the neural network model by about 26% for 2D velocities and positions during GPS outages.

scholarly journals On Computing Impulse Responses from Frequency-Domain Finite Element Solutions

2021 ◽  
pp. 2050024
Author(s):  
A. G. Prinn
Keyword(s):  
Finite Element ◽  
Frequency Domain ◽  
Impulse Response ◽  
Phase Error ◽  
Complex Impedance ◽  
Impedance Boundary Condition ◽  
Impulse Responses ◽  
Impedance Boundary ◽  
Inverse Fourier Transformation ◽  
Source Signal

In acoustics, knowledge of the impulse response of a system is often important. While impulse responses may be measured, they may also be predicted using numerical methods. This work considers the generation of impulse responses from frequency-domain finite element solutions. It is shown that these impulse responses, obtained by inverse Fourier transformation, are noncausal. Through error analysis, it is demonstrated that the noncausality can be reduced by increasing the duration of a source signal used to excite a simulated system. It is found that increasing the source signal duration increases the dispersion-related phase error present in the simulated impulse responses. The findings of this study are used to simulate an impulse response for a system with a nonuniform, frequency-dependent, complex impedance boundary condition.

Impulse Response Method for Frequency-Dependent Pipeline Transients

1989 ◽  
Vol 111 (4) ◽  
pp. 478-483 ◽  
Author(s):  
Lisheng Suo ◽  
E. B. Wylie
Keyword(s):  
Fourier Transform ◽  
Impulse Response ◽  
Method Of Characteristics ◽  
Response Analysis ◽  
Frequency Response Analysis ◽  
Response Frequency ◽  
Frequency Dependent ◽  
Physical Experiments ◽  
Piping Systems ◽  
Response Method

An effective numerical method is presented to compute transients in piping systems in which frequency-dependent parameters influence the response. Frequency-dependent friction is utilized as the parameter-of-concern herein, however, the procedure can accommodate other factors such as frequency-dependent wavespeed equally well. The method, a variation in the impulse response method, is developed from the frequency response analysis and incorporates the fast Fourier transform. Examples are included showing the application of the method in computing both classic waterhammer and transients in pipes with frequency-dependent friction. Computed results agree very well with those from the standard method of characteristics and with physical experiments.

The Nexus Between Johannesburg Stock Exchange and the United States Unemployment Rate Announcement: An Impulse Response Analysis

2018 ◽  
Vol 10 (3(J)) ◽  
pp. 160-168
Author(s):  
Misheck Mutize ◽  
Victor Virimai Mugobo
Keyword(s):  
United States ◽  
South African ◽  
Impulse Response ◽  
Unemployment Rate ◽  
Stock Prices ◽  
Stock Exchange ◽  
The United States ◽  
Response Analysis ◽  
Johannesburg Stock Exchange ◽  
The Us

The study explores the relationship between the unemployment rate in the United States and South Africa’s stock prices from the beginning of 2013 to the last day 2017. The objective of this paper is to examine the impact of the US unemployment rate announcement on the South African financial market. Results of Impulse Response analysis show that there is a very minimal impact from the US unemployment announcement to South Africa’s stock prices which disappears within two days of the announcement. In addition, the Johannesburg stock exchange index marginally responds to own shocks, which marginally fades away within two days. These findings imply that the changes in the US employment policies have a direct ripple effect on the South African macroeconomic environment, its investing public sentiments and corporate confidence on the future prospects of businesses.

A numerical and experimental implementation and integration of Steiglitz–McBride algorithm with the frequency domain IIR filtering technique for active vibration control

2016 ◽  
Vol 24 (6) ◽  
pp. 1086-1100
Author(s):  
Utku Boz ◽  
Ipek Basdogan
Keyword(s):  
Computational Complexity ◽  
Vibration Control ◽  
Frequency Domain ◽  
Impulse Response ◽  
Time Domain ◽  
Vibration Suppression ◽  
Active Vibration Control ◽  
Infinite Impulse Response ◽  
Iir Filter ◽  
Active Vibration

In adaptive control applications for noise and vibration, finite ımpulse response (FIR) or ınfinite ımpulse response (IIR) filter structures are used for online adaptation of the controller parameters. IIR filters offer the advantage of representing dynamics of the controller with smaller number of filter parameters than with FIR filters. However, the possibility of instability and convergence to suboptimal solutions are the main drawbacks of such controllers. An IIR filtering-based Steiglitz–McBride (SM) algorithm offers nearly-optimal solutions. However, real-time implementation of the SM algorithm has never been explored and application of the algorithm is limited to numerical studies for active vibration control. Furthermore, the prefiltering procedure of the SM increases the computational complexity of the algorithm in comparison to other IIR filtering-based algorithms. Based on the lack of studies about the SM in the literature, an SM time-domain algorithm for AVC was implemented both numerically and experimentally in this study. A methodology that integrates frequency domain IIR filtering techniques with the classic SM time-domain algorithm is proposed to decrease the computational complexity. Results of the proposed approach are compared with the classical SM algorithm. Both SM and the proposed approach offer multimodal vibration suppression and it is possible to predict the performance of the controller via simulations. The proposed hybrid approach ensures similar vibration suppression performance compared to the classical SM and offers computational advantage as the number of control filter parameters increases.

Impulse response method for defect detection in polymers: Description of the method and preliminary results

2016 ◽  
Vol 55 ◽  
pp. 78-87 ◽  
Author(s):  
Marco Caniato ◽  
Federica Bettarello ◽  
Lucia Marsich ◽  
Alessio Ferluga ◽  
Orfeo Sbaizero ◽  
...  
Keyword(s):  
Impulse Response ◽  
Defect Detection ◽  
Preliminary Results ◽  
Response Method
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