This paper presents the results of a study covering measurement and characterization of the wide-band impulsive noise present in a digital TV radio channel. Measurements were conducted at a frequency of 762 MHz in different outdoor and indoor environments using vertical and horizontal polarization. The measurement system was built on commercial equipment only. The calibration process, which is an important stage of this kind of measurements, is described. To analyze the measurements the impulsive noise has been modeled as a pulse train where the pulse amplitude, pulse duration and elapsed time between pulses are considered random variables. It has been found that the pulse duration and elapsed time between pulses is not dependent on the antenna polarization while the pulse amplitude is, especially in the case of the noise generated by a fluorescent lamp. It has also been found that the pulse duration of the noise measured in the outdoor environments presents some clustering features and is correlated with the pulse amplitudes. This correlation may be caused by a RF noise bandwidth that is larger than the bandwidth of the measurement system. The noise in busy streets presents larger pulse durations, larger amplitude, and shorter elapsed time between pulses that the noise measured in a pedestrian area. Several statistical tests have been done to find the distribution function that best fits these random variables. Power Rayleigh, lognormal, exponential, Poisson, and Gamma distributions have been tested. According to the assessment carried out, none of the distribution functions is adequate to model the pulse amplitudes or the elapsed time between pulses, while the pulse duration seems to be Gamma distributed.

Impulsive noise measurements and characterization in a UHF digital TV channel

New emission limit requirements are needed to protect digital communication systems from radiated interference. Traditionally, standard emission requirements have focused on protecting analog amplitude modulated radio services. However, developments in digital technology require emission limit requirements adapted to protect digital radio communication services. The amplitude probability distribution (APD) of the envelope or the quadrature components of an interfering signal has been shown to be related to the bit error probability of some digital radio receivers. However, a general description of the APD of an interfering signal and its impact on digital coherent radio receivers has not been presented. The aim of this paper is to clarify this relationship for a larger group of digital radio receivers. A method of incorporating the APD in conventional error expressions developed for digital coherent radio receivers in additive white Gaussian noise is presented. Furthermore, the relation between the maximum error probability for different digital modulation schemes and the APD is described, which allows definition of emission requirements on the APD

Relation between the amplitude probability distribution of an interfering signal and its impact on digital radio receivers

Measurements of radio impulsive noise in industrial and urban electromagnetic environments have been conducted and its effect on radio communication systems is studied. An impulsive noise measurement system has been designed and built. It meets and improves the main features of classical equipments used to measure noise, offering both in-phase and quadrature outputs simultaneously. The system was carefully calibrated before a measurement campaign was conducted in industrial and urban environments to get impulsive noise statistics. Results show that shot noise events are less frequent in the industrial than at the urban environment, but when a noise event occurs, noise pulses appear more grouped in bursts, exhibit larger amplitude and wider bandwidth. In both cases, shot noise pulses have very high amplitude, long duration and high repetition rate, so the performance of radio communication systems could be significantly reduced in the industrial environment. The effect of the noise burst on digital radio communication systems using different types of modulation is analyzed.

Interference and impairments in radio communication systems due to industrial shot noise

Measurements of impulsive noise in the universal mobile telecommunications system (UMTS) electromagnetic environment in urban areas have been conducted and its effect on the UMTS system is analyzed. An impulsive noise-measurement system for the UMTS frequency band has been designed and built, which meets and improves the main features of classical equipments used to measure noise, offering inphase and quadrature outputs simultaneously. This measurement system was carefully calibrated before a measurement campaign was conducted in an urban environment to get impulsive noise statistics. Results show that noise pulses may have high power, long duration, and high repetition rate, so the performance of UMTS could be significantly reduced.

Urban wide-band measurement of the UMTS electromagnetic environment

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.

C. Amato

Papers

Measurements of Amplitude Probability Distributions and Power of Automobile Ignition Noise at HF