Richard W. Wiese

Modeling signal strength range of TPMS in automobiles

Results of a three-dimensional electromagnetic (3D EM) simulation of a generic automobile is presented. Full wave MoM based 3D EM code was applied to compute the normalized received power between a transmitter and a receiver of a tire pressure monitor system (TPMS) on a simplified model of an automobile. An overview of the procedure used to calculate the TPMS normalized received power using the EM modeling procedure is provided.

Development of Reduced Order Model for Modeling Performance of Tire Pressure Monitoring System

An electromagnetic (EM) math model of TPMS calculates the data links RF pathless profile of each four wheels that was later translated into an estimate of packet errors registered by the TPM system using a higher level system simulation tool. A reduced order model (ROM) of a vehicle structure for modeling TPMS performance was developed after investigating four vehicle models having different degree of complexity and identifying effects of various vehicle structures on the pathless profile. Pathless profile of the ROM of a CTS vehicle compared very well with that of the measurement data if variances are minimal in the RF channels between the transmitter and the receiver. The higher-level system model showed the system performance of the ROM converged to that of the measurement data.

RF Link Budget Analysis of a 315MHz Wireless Link for Automotive Tire Pressure Monitoring System

Inclusion of a Tire Pressure Monitoring System (TPMS) in a vehicle presents a new design challenge in terms of automotive electrical system integration. This paper examines the dynamic RF signal path characteristics of a TPMS data link operating at 315MHz as a short-range device Electromagnetic modeling results and anechoic chamber measurements provide signal path loss estimates for various system configurations. A qualitative link budget formulation is proposed that accounts for observed dynamic and quasi-static variation of the TPMS signal.

Characterizing performance of tire pressure monitoring systems using experimental measurements and system simulations

In this paper, we focus on the design and development of a system simulator that can assess the performance of a direct measurement TPMS in various operational scenarios. Our end goal is to use this TPMS simulator as a virtual test environment for a number of different experimental scenarios and possibly reduce the number of actual physical tests that may be required otherwise.

Assessment of automobile radio system performance in noisy EM environments

A procedure is presented to simulate the complete automobile radio system, from antenna to speaker. The method involves generating reduced order models of all relevant components and interactions, which are then linked together in a time-domain system solver. To illustrate the usefulness of this simulation capability in vehicle-level system design a novel algorithm for automated computer rating of automobile audio tracks is developed. The algorithm uses wavelet and Fourier decompositions for automated computer rating of audio quality. The algorithm developed is validated by comparing its output to a study using human subjects to score recorded audio tracks

Impact of Inter-Vehicular Interference on the Performance of Tire Pressure Monitoring Systems

In this paper, we present a system simulator that can evaluate the performance of direct measurement Tire Pressure Monitoring Systems (TPMS) in various operational scenarios. We also discuss the following capabilities of the simulator: (1) modeling the wireless channel characteristics experienced by the signal between various transmitters and the receiver of a given vehicle, (2) modeling collisions among wireless signals of a given vehicle and those of the nearby vehicles, and (3) quantifying the impact of wireless channel characteristics and collisions among wireless signals on the performance of the TPMS. Using results for hypothetical simulation scenarios, we demonstrate the impact of wireless channel characteristics, receiver sensitivity level, and inter-vehicular interference on the performance of the TPMS.

Objective Metric for Antenna Patterns Comparison Using Mahalanobis-Taguchi-Gram-Schmidt Method

The application of the modified MTGS method offers a practical alternative to elementary statistical calculation for generating objective quantitative metric to measure the similarity between two data sets. Since the MTGS method can capture many degrees of variation between two data sets and discriminate between data sets which have dissimilar average magnitudes, correlation coefficients and uniformity, its application is much more efficient than elementary statistical analysis that evaluates each metric individually. The feasibility of modified MTGS method for similarity analysis, which used the difference in MD values calculated with MTGS method for the antenna radiation pattern similarity comparison, was successfully demonstrated through three test cases.

Parametric Study of Roof Geometry and Roof Rack Crossbar Effects on the Performance of Multi-Band Vehicle Antennas

A parametric study of the roof geometry and roof rack crossbar interactions with a multi-antenna module is presented. The effects of varying roof curvatures on the antenna performance are analyzed and compared to a flat roof. In addition, roof rack interactions for varying roof rack crossbar locations relative to the antenna are studied for different roof curvature cases. The results for GPS and SDARS will be presented.

Impact of Intra-Vehicular Electromagnetic Interference On Tire Pressure Monitoring Systems

In this paper, we present a system simulator that can assess the performance of a direct measurement Tire Pressure Monitoring System (TPMS) in various operational scenarios. We also discuss the following capabilities of the simulator: (1) modeling the wireless channel characteristics experienced by the signals between various transmitters and the receiver of a given vehicle, (2) modeling intra-vehicular electromagnetic interference (EMI) as experienced by the wireless signals, and (3) quantifying the impact of wireless channel characteristics and intra-vehicular EMI on the system packet error rate (PER). Using quantitative results for hypothetical simulation scenarios, we demonstrate the impact of different levels of Additive White Gaussian Noise (AWGN) and Amplitude Modulated (AM) Noise on the system PER performance.

Automotive audio noise assessment. human hearing factors and complexity

Vehicle audio subsystems are becoming increasingly complex. In addition to providing audio entertainment with higher fidelity at higher power levels vehicles have become generally quieter with respect to road, wind and power train noise. The overall effect is an expanded dynamic range. When the engineer is faced with reducing EMC related noise in an entertainment system what metrics are to be used to define relative performance? This paper presents an overview of the complexity of perceived audio quality. Accepted characteristics of human hearing and industry attempts to provide objective metrics to aid perception of quality are presented Keywords-EMC, audio, noise, automotive I. INTRODUCTION Automotive audio systems are increasingly more complex. At one time AM radio broadcast was the only offering with its limited bandwidth, noise susceptible modulation format and a single speaker mounted in the dashboard. Today the automotive entertainment system is a distributed and fully integrated subsystem which includes numerous broadcast and recorded media formats with exceptional high fidelity reproduction capability. Vehicles have also become quieter with respect to road, wind and power train noise. The overall effect is an expanded dynamic range for the listening experience. Entertainment system performance and EMC related noise is a system integration concern which appears late in the development process. Invariably there is a difference of opinion within the product development community on how bad a noise is perceived to be and whether it really is a problem to the consumer. When the EMC engineer is faced with mitigating this noise what metrics and guidelines are to be employed to define relative performance? This paper outlines the complexity of perceived audio quality based on accepted characteristics of human hearing and industry attempts to provide objective metrics to aid perception of quality.