<p> This thesis focuses on the noise model verification at both device and circuit levels using circuit simulators. The techniques and procedures developed in this thesis are general and can be applied to any proposed RF noise model equations. To fulfil the two tasks, three main topics have been accomplished. First, a general noise source implementation method has been presented in detail in this thesis and is verified with measurements for both long and short-channel MOSFETs. This method provides a simple and effective way to implement the enhanced channel noise and induced gate noise of MOSFETs without increasing the simulation complexity for the simulators.</p> <p> Second, a systematic procedure to refine the model parameters used in noise calculation is presented. For a model to accurately predict the HF noise characteristics, the accuracy in the prediction of both DC and AC characteristics has to be ensured. The procedure proposed in this thesis provides both DC and AC model parameter verification and optimization for RF noise simulation purpose.</p> <p> Third, as for benchmark circuits to verify noise model at the circuit level, two LNA designs are proposed in the thesis. The first design gives the emphasis on the noise reduction technique and the LNA design procedure. The proposed noise reduction technique gives circuit designers more control on noise figure minimization through noise matching. The second design is used to experimentally verify the noise model at the circuit level.</p> / Thesis / Master of Applied Science (MASc)

An accurate noise measurement is essential to a proper characterization of a noisy device. In the 1950s, the IRE first proposed the classical noise parameters for characterizing a noisy linear two-port network, and subsequently a measurement and extraction procedure. Since then, the task of accurately characterizing the parameters has always been challenging due to the sensitive nature of the noise parameters. This is especially so for an on-wafer device noise measurement, as opposed to that of a packaged device, due to various factors such as the lower noise level and losses in the signal path. Combined with the downscaling of the MOSFET technology in recent decades, which also improved the device's noise performance, they make noise measurement and characterization become even more difficult. A typical noise measurement starts with the calibration or characterization of the measurement system. This step is as important as the measurement itself in terms of the ultimate accuracy of the results. This thesis presents a noise receiver characterization method which improves upon existing methods by accurately taking into account the different reflection coefficient of the noise source between its hot and cold states. The improvement allows more precise determination of the receiver characterizations. Numerous studies have investigated the effect of the choice of the source terminations on the noise measurement results. These studies often provided contradicting suggestions on the selection techniques. In the thesis, a selection technique is proposed that allows quick determination of desirable terminations. Analyses using real measurement data on a 65 nm n-type MOSFET show that the proposed technique is able to provide terminations that yield noise parameters with smaller uncertainties relative to other terminations. / Thesis / Master of Applied Science (MASc)

This thesis is concerned with intensity characteristics of conditioned stimuli in acquisition of a conditioned emotional response (CER) in rats. A comparison was made of CSs which differed (between groups) with respect to amount and direction of change in white noise from a constant background stimulation level. The measure of conditioning was the degree to which the CS disrupted ongoing, food-motivated, bar-pressing activity. The major findings were (1) that rate of conditioning was a monotonic increasing function of amount of intensity change in either direction; and (2) an increase in noise intensity from background X to CS Y produced more rapid acquisition of the CER than did a decrease from background Y to CS X. (3) During pretests, a noise increase produced a small, but reliable, Increase in rate of bar-pressing, while a noise decrease produced a slight suppression. / Thesis / Master of Arts (MA)

No / Recent progress in the development of European standards has allowed the in situ testing of roadside noise barriers. CEN/TS 1793-5 describes a test method using maximum length sequences (MLS) for the characterisation of airborne sound insulation. However, many barriers are tested according to a laboratory standard, EN 1793-2, based on measurements carried out in reverberant chambers and in the case of timber barriers with a relatively low airborne sound insulation it is not clear to what extent the results of the two tests compare. The paper describes the results of tests carried out using both methods. Six samples of timber barrier were compared including single-leaf and double-leaf constructions and single-leaf constructions with an absorptive core. Very good agreement was found especially when account was taken of the valid frequency range in each test method. The results open up the possibility of routinely evaluating the performance of timber barriers at the roadside where build quality can be variable and there are concerns that the acoustic performance may not match that obtained under laboratory test conditions where typically the barrier is more carefully constructed.

Yes / The in situ measurement of the airborne sound insulation, as outlined in EN 1793-6:2012, is becoming a common means of quantifying the performance of road traffic noise reducing devices. Newly installed products can be tested to reveal any construction defects and periodic testing can help to identify long term weaknesses in a design. The method permits measurements to be conducted in the presence of background noise from traffic, through the use of impulse response measurement techniques, and is sensitive to sound leakage. Factors influencing the measured airborne sound insulation are discussed, with reference to measurements conducted on a range of traffic noise barriers located around Auckland, New Zealand. These include the influence of sound leakage in the form of hidden defects and visible air gaps, signal-to-noise ratio, and noise barrier height. The measurement results are found to be influenced by the presence of hidden defects and small air gaps, with larger air gaps making the choice of measurement position critical. A signal-to-noise ratio calculation method is proposed, and is used to show how the calculated airborne sound insulation varies with signal-to-noise ratio. It is shown that the measurement results are influenced by barrier height, through the need for reduced length Adrienne temporal windows to remove the diffraction components, prohibiting the direct comparison of results from noise barriers with differing heights. / The authors would like to thank the NZ Transport Agency for sponsoring the Auckland traffic noise barrier testing work, and the Auckland Motorway Alliance for assisting with access to the test sites.

Experiments were performed to document the turbulent flowfield produced downstream of an airfoil encountering an intense streamwise vortex. This type of perpendicular airfoil--vortex interaction commonly occurs in helicopter rotor flows. The experiments presented here thus provide useful information for the prediction of helicopter noise, particularly BWI noise. Three-component velocity and turbulence measurements were made in unprecedented detail using a computerized miniature four-sensor hot-wire probe system; revealing much about the structure and behavior of this flow over a range of conditions. The interaction between the vortex and the airfoil wake leaves the vortex surrounded by a large region of intense turbulence unlike the turbulence surrounding an isolated vortex. Even for close separations, the vortex core passes the airfoil virtually unchanged. However, vorticity of opposite sign is shed by the airfoil in response to the angle of attack distribution induced by the vortex resulting in an unstable circulation distribution according to Rayleigh's criterion. Simple theoretical models adequately describe the shed vorticity distribution of the airfoil and the unstable circulation distribution it imparts on the vortex. As the flow develops, the vortex continuously distorts the airfoil wake. The strain rates imparted by the vortex on the spanwise vorticity contained in the airfoil wake result in an anisotropic, turbulence producing stress field. For several chord lengths downstream, the vortex core remains laminar and little change is seen in the unstable circulation distribution. While the vortex core is laminar, turbulent fluctuations measured in the core are the result of inactive wandering motions and the characteristic length and velocity scales of the flat portion of the vortex wake appear to be appropriate scales for the fluctuations. Eventually, the vortex core becomes turbulent as indicated by an increase in high frequency velocity fluctuation levels of more than an order of magnitude. Subsequently, the circulation distribution reorganizes to a stable distribution. A loss in core circulation occurs due to a decrease in the peak tangential velocity which is proportionately larger than the increase in the vortex core radius. The peak tangential velocity decreases to the point where it is exceeded by the axial velocity deficit---another unstable situation. These effects increase with decreased separation between the vortex and the airfoil, but appear to be largely independent of airfoil angle of attack an only weakly dependent upon vortex strength. / Ph. D.

An advanced model of active control of fan noise for ultra high bypass turbofan engines has been developed. This model is based on a boundary integral equation method and simulates the propagation, radiation and control of the noise generated by an engine fan surrounded by a duct of finite length and cylindrical shape, placed in a uniform flow. Control sources, modeled by point monopoles placed along the wall of the engine inlet or outlet duct, inject anti-noise into the duct to destructively interfere with the sound field generated by the fan. The duct inner wall can be lined or rigid. Unlike current methods, reflection from the duct openings is taken into account, as well as the presence of the evanescent modes. Forward, as well as backward (i.e., from the rear of the engine), external radiation is computed. The development of analytical expressions for the sound field resulting from both the fan loading noise and the control sources is presented. Two fan models are described. The first model uses spinning line sources with radially distributed strength to model the loading force that the fan blades exert on the medium. The second model uses radial arrays of spinning point dipoles to simulate the generation of fan modes of specific modal amplitudes. It is shown that these fan models can provide a reasonable approximation of actual engine fan noise in the instance when the modal amplitude of the propagating modes or the loading force distribution on the fan blades, is known. Sample cases of active noise control are performed to demonstrate the feasibility of the model. The results from these tests indicate that this model 1) is conducive to more realistic studies of active control of fan noise on ultra high bypass turbofan engines because it accounts for the presence of evanescent modes and for interference between inlet and outlet radiation, which were shown to have some impact on the performance of the active control system; 2) is very useful because it allows monitoring of any region of the acoustic field; 3) is computationally fast, and therefore suitable to conduct parametric studies. Finally, the potential that active noise control techniques have for reducing fan noise on an ultra high bypass turbofan engine is investigated. Feedforward control algorithms are simulated. Pure active control techniques, as well as hybrid (active/passive) control techniques, are studied. It is demonstrated that active noise control has the potential to reduce substantially, and over a relatively large far field sector, the fan noise radiated by an ultra high bypass turbofan engine. It is also shown that a hybrid control system can achieve significantly better levels of noise reduction than a pure passive or pure active control system, and that its optimum solution is more robust than the one achieved with a pure active control system. The model has shown to realistically predict engine acoustic behavior and is thus likely to be a very useful tool for designing active noise control systems for ultra high bypass turbofan engines. / Ph. D.

Noise-induced hearing loss and tinnitus are the two most prevalent service-connected disabilities for veterans receiving compensation (Department of Veterans Affairs, 2010). While it is possible to protect against noise-induced hearing damage with hearing protection devices (HPDs) and hearing protection enhancement devices (HPEDs), military personnel resist using HPDs/HPEDs that compromise their situational awareness, including ability to localize enemy gunfire. Manufacturers of a new generation of "pass-through" level-dependent HPEDs claim these devices preserve normal or near-normal hearing. A research study was conducted to evaluate localization of suprathreshold gunshot's report (from blank ammunition) with one passive (3M's Single-Ended Combat Arms earplug) and three electronic level-dependent HPEDs (Peltor's Com-Tac II electronic earmuffs and Etymotic's EB 1 and EB 15 High-Fidelity Electronic BlastPLG earplugs), in comparison to the open ear in an in-field test environment with ambient outdoor noise and in 82 dBA diesel truck noise with nine normal and four impaired hearing participants. Statistical analysis showed worse localization accuracy and response time with the Com-Tac II earmuffs than with the other tested HPEDs. Performance with all HPEDs was worse than that with the open ear, except on right-left confusions, in which the Com-Tac II stood alone as worst, and in response time, for which the EB 1 earplug was equivalent to the open ear. There was no significant main effect of noise level. There was generally no significant effect of hearing ability. However, participants with impaired hearing had more right-left confusions than those with normal hearing. Subjective ratings related to localization generally corroborated objective localization performance. Three follow-up experiments were performed: (1) an assessment of the effect of microphone position on localization with the EB 15, which showed a limited advantage when the microphone was positioned near the opening of the ear canal compared to when it was facing outwards; (2) an assessment of Etymotic's QuickSIN test as a predictor localization performance, which showed little correlation with localization performance; and (3) an assessment of the acoustic properties of the experiment site, which was inconclusive with regards to the direction of dominant sound energy from gunshots from each of the shooter positions. / Ph. D.

Signal detection and modulation classification are becoming increasingly important in a variety of wireless communication systems such as those involving spectrum management and electronic warfare and surveillance, among others. The majority of the signal detection and modulation classification algorithms available in the literature assume that the additive noise has a Gaussian distribution. However, while this is a good model for thermal noise, various studies have shown that the noise experienced in most radio channels, due to a variety of man-made and natural electromagnetic sources, is non-Gaussian and exhibits impulsive characteristics. Unfortunately, conventional signal processing algorithms developed for Gaussian noise conditions are known to perform poorly in the presence of non-Gaussian noise. For this reason, the main goal of this dissertation is to develop statistical signal processing algorithms for the detection and modulation classification of signals in radio channels where the additive noise is non-Gaussian. One of the major challenges involved in the design of these algorithms is that they are expected to operate with limited or no prior knowledge of the signal of interest, the fading experienced by the signal, and the distribution of the noise added in the channel. Therefore, this dissertation develops new techniques for estimating the parameters that characterize the additive non-Gaussian noise process, as well as the fading process, in the presence of unknown signals. These novel estimators are an integral contribution of this dissertation. The signal detection and modulation classification problems considered here are treated as hypothesis testing problems. Using a composite hypothesis testing procedure, the unknown fading and noise process parameters are first estimated and then used in a likelihood ratio test to detect the presence or identify the modulation scheme of a signal of interest. The proposed algorithms, which are developed for different non-Gaussian noise models, are shown to outperform conventional algorithms which assume Gaussian noise conditions and also algorithms based on other impulsive noise mitigation techniques. This dissertation has three major contributions. First, in environments where the noise can be modeled using a Gaussian mixture distribution, a new expectation-maximization algorithm based technique is developed for estimating the unknown fading and noise distribution parameters. Using these estimates, a hybrid likelihood ratio test is used for modulation classification. Second, a five-stage scheme for signal detection in symmetric α stable noise environments, based on a class of robust filters called the matched myriad filters, is presented. New algorithms for estimating the noise distribution parameters are also developed. Third, a modulation classifier is proposed for environments in which the noise can be modeled as a time-correlated non-Gaussian random process. The proposed classifier involves the use of a whitening filter followed by likelihood-based classification. A new H_â filter-based technique for estimating the whitening filter coefficients is presented. / Ph. D.

Turbulent flow over a rough surface produces sound that radiates outside the near wall region. This noise source is often at a lower level than the noise created by edges and bluff body flows, but for applications with large surface area to perimeter ratios at low Mach number, this noise source can have considerable levels. In the first part of this dissertation, a detailed study is made of the ability of the Glegg & Devenport (2009) scattering theory to predict roughness noise. To this end, comparisons are made with measurements from cuboidal and hemispherical roughness with roughness Reynolds numbers, hu_Ï /ν, ranging from 24 to 197 and roughness height to boundary layer thickness ratios of 5 to 18. Their theory is shown to work very accurately to predict the noise from surfaces with large roughness Reynolds numbers, but for cases with highly inhomogeneous wall pressure fields, differences grow between estimation and measurement. For these surfaces, the absolute levels were underpredicted but the spectral shape of the measurement was correctly determined indicating that the relationship of the radiated noise with the wavenumber wall pressure spectrum and roughness geometry appears to remain relatively unchanged. In the second part of this dissertation, delay and sum beamforming and least-squares analyses were used to examine roughness noise recorded by a 36-sensor linear microphone array. These methods were employed to estimate the variation of source strengths through short fetches of large hemispherical and cuboidal element roughness. The analyses show that the lead rows of the fetches produced the greatest streamwise and spanwise noise radiation. The least-squares analysis confirmed the presence of streamwise and spanwise aligned dipoles emanating from each roughness element as suggested by the LES of Yang & Wang (2011). The least-squares calculated source strengths show that the streamwise aligned dipole is always stronger than that of the spanwise dipole, but the relative magnitude of the difference varies with frequency. / Ph. D.