David Guerra

Medium wave DRM field test results in urban and rural environments

This paper presents the results of the first Spanish field trial carried out to analyze a DRM (Digital Radio Mondiale) system in the medium-wave band. A 4-kW average power omni directional ground-wave experimental DRM transmission at a frequency of 1359 kHz was surveyed by means of a measurement vehicle for fixed and mobile reception. Several radial routes starting from the transmitter site provided rural and suburban behavior features of the system. Urban reception trials were performed in several dense and open streets of Madrid, within the expected coverage area. Field strength threshold values were determined for the tested transmission configurations and compared with the AM ground-wave ITU model predictions. Reliability versus distance from the transmitter is stated in this paper for different transmission configurations and the causes of dropouts for different reception conditions are explained. This analysis took into account subjective quality features of each configuration, providing practical planning parameter values.

Software tool for the analysis of potential impact of wind farms on radiocommunication services

The prediction of the potential impact of a wind farm on the existing radiocommunication services before its installation allows the planning of alternative solutions to ensure the coexistence of wind energy and telecommunication facilities. Although some guidelines for safeguarding radiocommunication services have been recently published, the precise impact on a specific service can only be determined on a case-by-case basis, due to the multiple factors that must be considered in the analysis. This paper presents a software tool that allows the accurate analysis of the degradation of the different radiocommunication systems. The calculations are based on the configuration of a specific wind farm and the different transmitters and receivers over a terrain database containing high resolution altimetry data. For each type of service, suitable calculation algorithms and interference criteria are applied. Graphic and numerical results of the analysis are presented on a map, which allows an on-the-spot evaluation of the degradation mechanisms for each wind turbine.

Medium Wave Digital Radio Mondiale (DRM) Field Strength Time Variation in Different Reception Environments

This paper examines the temporal variability in fixed reception of the ground-wave propagated DRM (Digital Radio Mondiale) signal. This field strength analysis in the medium wave band has been performed using the first Spanish DRM field trial. Several fixed reception points located along radial routes provided the field strength sample distributions in rural and suburban areas. Additionally a second measurement campaign was carried out in several dense and open areas of downtown Madrid. The maximum likelihood estimations and logarithmic functions were used to analyse the fit of the experimental data with theoretical statistical distributions. A deep analysis of the most important parameters of the distribution has been carried out in order to characterize the field strength behavior in the different reception situations. It has been taken into account the influence of environment, measurement time interval, distance to the transmitter and the presence of critical reception impairments. The most remarkable result of this study has shown that the time variability of the ground-wave medium wave DRM channel is well approximated by a Log Normal and also by a Nakagami process. The Log Normal distribution is preferred as it is the one considered by the analog medium wave broadcasts for the ground-wave propagation case

DTV reception quality field tests for portable outdoor reception in a single frequency network

This paper presents a field measurement campaign developed to study the influence of the special features of a Single Frequency Network (SFN) reception in the C/N thresholds applicable to portable DTV reception. The measurements presented here were performed inside coverage areas of the nationwide SFN which broadcasts DTV (COFDM 8 K mode) services in Spain. The aim of this paper is to present some network planning reference values for portable reception in urban environments where both multipath and multiple transmitter reception have to be taken into account to ensure a good quality of service.

Field measurement based characterization of the wideband urban multipath channel for portable DTV reception in single frequency networks

This paper presents a study developed to obtain several parameters of the small scale fading of the wideband propagation channel applied to the portable and mobile reception of Digital Terrestrial Television (DTV) services in an urban Single Frequency Network (SFN) environment. The study is focused on the calculation of some relevant parameter values related to the multipath behavior of the channel, using field data collected in a real network. Mean values for the Root mean square Delay Spread (RDS) and the frequency domain Level Crossing Rate (LCR) are given, together with an analysis of the influence of the specific environment and network (SFN) features.

External Noise Measurements in the Medium Wave Band

This paper presents an up to date study on external noise levels in the medium wave band based on field trials carried out in Spain and Mexico during years 2004 and 2005 respectively. External noise levels predicted by the ITU-R P.372 recommendation are based on measurements carried out more than 30 years ago and no updated results for the medium wave band have been published in this time. An increment on these noise levels have been measured, which leads to a significant impact on the minimum usable field strength requirements for the broadcasting systems used in this frequency band, such as the new Digital Radio Mondiale (DRM) and In-Band/On-Channel (IBOC) systems

Digital-Radio-Mondiale (DRM) Measurement-System Design and Measurement Methodology for Fixed and Mobile Reception

This paper presents measurement-system design and measurement techniques developed to study digital-radio-mondiale signal behavior and system performance. The solution proposed considers different reception conditions and environments. Some aspects, like antenna selection and both internal and external noise measurements, have turned out to be key factors and are also presented.

An Empirical Comparative Study of Prediction Methods for Estimating Multipath Due to Signal Scattering From Wind Turbines on Digital TV Services

Several authors have theoretically studied the effect of wind turbines on the propagation of electromagnetic waves in the UHF band. The International Telecommunication Union also proposes a simplified model to evaluate the impact caused to television reception by a wind turbine in the Recommendation ITU-R BT.805. This paper presents an empirical study of the above-mentioned prediction methods for estimating signal scattering from wind turbines in the UHF band, comparing predicted values with empirical data obtained from a DTV measurement campaign carried out in Spain. As signal scattering is independent of the transmission standard or modulation, the results are applicable to any broadcasting and wireless communication signals in the UHF band that may be affected by the multipath interference caused by a wind farm.

Analysis of the Attenuation Caused by the Influence of Orography in the Medium Wave Band

This paper presents attenuation values due to the influence of orography in the MW band, based on an analysis of data recorded in a measurement campaign. The decisive influence of the distance of the obstacle from the receiver is demonstrated, and this parameter has been considered in the analysis. Values for the range of the influence are indicated for different values of the height of a single obstacle. These attenuation values are greater than the ones assumed in classical methods, and coincide with measurement campaigns developed by DRM (digital radio mondiale) consortium members. Accuracy in calculating the attenuation due to the irregular terrain is necessary in planning the coverage of digital services, where it is necessary to provide adequate field strength in a high percentage of locations.

Carrier and Noise Measurements in the Medium Wave Band for Urban Indoor Reception of Digital Radio

This paper presents a study of indoor digital radio reception in the Medium Wave band. The results are based on a large database of measurements in indoor locations in cities in northern Spain in frequencies from 600 to 1600 kHz. The paper proposes a prediction model for indoor field strength. The results are combined with indoor noise levels to study the statistics of available C/N (Carrier to Noise) ratios. The model is intended to help broadcasters planning digital broadcasting networks in Medium Wave for indoor reception. Signal time and space variability have also been studied and reference values are provided in the paper. The paper includes curves to calculate indoor losses in respect to ground wave propagation values provided by ITU-R P.368.