The authors present the results of average and impulsive noise measurements inside several office buildings and retail stores. The noise measurement system operated at 918 MHz, 2.44 GHz, and 4 GHz with a nominal 40-MHz, 3-dB RF bandwidth. Omnidirectional and directional antennas were used to investigate the characteristics and sources of RF noise in indoor channels. Statistical analyses of the measurements are presented in the form of peak amplitude probability distributions, pulse duration distributions, and interarrival time distributions. Simple first-order mathematical models for these statistical characterizations are also presented. These analyses indicate that photocopiers, printers (both line printers and cash register receipt printers), elevators, and microwave ovens are significant sources of impulse noise in office and retail environments. >

http://faculty.poly.edu/~tsr/wp-content/uploads/CV/MTJ/1993-09-Measurements%20and%20models%20of%20radio%20frequency%20impulsive%20noise%20for%20indoor%20wireless%20communications.pdf

Measurements and models of radio frequency impulsive noise for indoor wireless communications

Nonparametric Methods in Statistics.

This paper presents an experimental study of impulsive noise in urban hospitals and clinics. A receiver was designed to resolve impulsive noise bursts as short as 2 /spl mu/s in duration in the 450-MHz band. Extensive measurements were taken at three hospitals and three clinics in three major urban areas across the United States and empirical models are provided for the amplitude, interarrival time, and duration distributions of observed impulsive noise events. This work may be used in modeling the noise found in indoor wireless communication channels.

Characteristics of impulsive noise in the 450-MHz band in hospitals and clinics

Fast and accurate diagnosis of array failure is important for the maintenance of array antennas. Locations of failing elements are usually detected using near field data, which may be polluted by noises. Most existing diagnosis methods assume non-impulsive noise in the measurement data. However, the practical measurement environment may contain impulsive noises, which has not been considered in existing methods. This work proposes to impose a penalty function in the residual between the measured and recovered near field. The impulsive noise in the near field data can then be suppressed by using an appropriate function as the penalty function. Furthermore, minimum lp-norm is imposed on the excitation vector. The condition imposed on the noise and the minimum lp-norm constraint on the excitation vector constitutes an optimization problem, which is solved using the unsupervised support vector regression. The proposed method is more accurate than existing methods when impulsive noise presents in the near field data, and it is able to deal with a wide range of number of failing elements by adjusting the value of p. Numerical results are presented to show the advantages of the proposed method and to study the choice of p.

Diagnosis of Array Failure in Impulsive Noise Environment Using Unsupervised Support Vector Regression Method

The need for electromagnetic compatibility (EMC) is crucial in health care environments, since electromagnetic interference (EMI) effects on critical care medical equipment may be life-threatening. Field strength measurements, made inside and outside five Montreal hospitals at frequencies between 30-1000 MHz, were compared to fields predicted using line-of-sight, and hybrid methods. Although measured fields generally remained below 3 V/m, EMI still caused medical equipment malfunctions at the five hospitals. The line-of-sight prediction method provided a worst-case estimate of the electromagnetic environmental hazard, predicting outside fields to within 20 dB of those measured. The hybrid method predicted fields to within 10 dB.

The measured and predicted electromagnetic environment at urban hospitals

1 Radio Frequency Measurements.- Fundamental Relationships: System Noise Factor.- 2 The Radio Frequency Environment.- Surface Electromagnetic Ambients.- Airborne Electromagnetic Ambients.- Satellite Electromagnetic Ambients.- References.- 3 Radio Propagation Fundamentals.- Propagation Processes Encountered in Radio Frequency Surveys.- Expressions for and Representation of Radio Propagation Processes.- References.- 4 Survey Planning.- Measurement Objectives and Procedures.- Site Evaluation and Selection.- Data Set Dimensions.- Test Duration Planning.- Measurement Risk Assessment in Power Density Surveying.- References.- 5 Characterization of Specialized Test Sites.- Electromagnetic Measuring Sites.- Measurements.- References.- 6 Antennas.- Antenna Parameters.- Relationships between Antenna Parameters.- Types of Receiving Antennas.- Antenna Calibration.- References.- 7 Receiving Equipment.- Receiving System.- Detector Functions.- Calibration of the Receiving System Predetection Circuit.- Detector Calibration.- Computer Support.- References.- 8 Survey Execution.- Documentation.- General Procedures of Surveying.- Power Distribution System Surveys.- References.- 9 Data Analysis Techniques.- Statistical Data Functions.- Sampling Quantization Error.- Least Squares Curve Fitting to Measured Data.- Correlation.- Signal Signature Correlation Measure.- References.- Glossary of Symbols.

Albert A. Smith

Papers

Measuring the radio frequency environment

Data Analysis Techniques

Radio Frequency Measurements

The Radio Frequency Environment

Characterization of Specialized Test Sites