D. de la Vega

Digital terrestrial television (COFDM 8K system) field trials and coverage measurements in Spain

This article presents the results of the first digital terrestrial television field trials and coverage measurements in Spain. First of all the VIDITER project is presented. The main objective of this work is to study the behavior of a whole digital terrestrial television network, from source coding up to the final signal reception. At this point, the experimental network installed in Madrid is described. Next, the measurement campaign is explained, first, by describing the network configuration used for these first field trials, and then, paying attention to the criteria used to select the measurement points and the parameter set to be tested. Some of the results obtained are shown as a first approach to the figures needed to develop and plan a fully operational digital terrestrial television service.

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.

Improving measurement techniques for testing digital broadcasting systems

This paper presents a methodology for efficient measurement of digital broadcasting signals, both with field trials or at the laboratory. The study is focused on measuring the C/N requirement for achieving a threshold BER. A comparison between the traditional techniques and the proposed methodology is analyzed in this work. The key of the methodology presented in this paper is the use of general purpose equipment such as a vector signal analyzer for recording baseband IQ samples.

Local-area field strength variation measurement of the digital terrestrial television signal (COFDM 8K) in suburban environments

This paper presents the results of a field measurement campaign at the experimental COFDM 8K digital terrestrial television network developed by the partners of the VIDITER project in Madrid (Spain). This article focuses on the field strength spatial variation distribution inside small coverage areas. Due to the fact that the distribution parameters strongly depend on the survey area type, during this first stage the only environments taken into account have been those traditionally considered as suburban.

Performance evaluation procedure for mobile DVB-T2 reception in urban environments

This paper presents a procedure for testing the mobile reception performance of DVB-T2 in urban environments. The main goal of this procedure is to reduce and simplify the measurement and processing stages, which are especially critical in the non-stationary and heterogeneous conditions of urban mobile reception. This procedure is supported by field trials carried out by the authors in these environments. The paper is focused on the DVB-T2 standard, but the methodology is also applicable to other new digital broadcasting systems designed for mobile urban reception, such as T2Mobile or DVB-NGH systems.

Methodology for the empirical analysis of the scattering signals from a wind turbine

This study proposes a field data-based methodology to characterize the scattered signals from wind turbines. The method is based on the scattering pattern of the wind turbine, empirically obtained from the estimation of the channel impulse response, which allows the accurate estimation of the amplitude and the time variation of the scattered signals. The analysis of the Channel Impulse Response at different situations, such as the rotation speed, the orientation of the turbine or the elevation and azimuth angles of the receiver location, will allow the proper characterization of this phenomenon, and therefore, the development of an empirical model for the estimation of the potential interference of wind farms.

First results of a field trial to evaluate the impact of wind turbines on DTV reception quality

This paper describes the first results of an extensive measurement campaign for evaluating the potential impact of scattered signals from wind turbines to terrestrial DTV reception quality in the UHF band. The field trial carried out in Northern of Spain has two main objectives: the empirical characterization of the scattered signals from the wind turbines, and the assessment of the potential impact of these scattered signals to the reception quality of the terrestrial DTV systems. This paper includes preliminary results relating to the second objective. Some empirical threshold carrier-to-noise ratios in the area of influence of a wind farm are presented in order to verify whether scattered signals from wind turbines could affect the threshold carrier-to-noise ratio required for quasi-error-free reception in the DVB-T system.

Field measurement based performance analysis of digital audio broadcasting (DAB) reception in mobile channels

This paper analyzes the reception of terrestrial digital audio broadcasting (T-DAB) signals at L-band in mobile channels, where multipath fading, Doppler spread and noise effects degrade the received signal. Receiver power levels and DAB base-band parameters have been recorded in order to study real performance of DAB signals in mobile propagation channels, with different vehicle speeds and with different multipath levels, considering environment types with different degrees of building density. The degradation of the received signal is presented in curve showing relationships between the pseudo-channel BER and the carrier to noise ratio. Threshold values for these two parameters are presented, considering different channel conditions (vehicle speed and environment type). The results presented in this paper contribute to a detailed characterization of the DAB signal degradation and the required C/N threshold values in mobile channels.

Adjacent and co-channel interference disturbances from a digital terrestrial television signal (COFDM-8K system) on analogue PAL systems

This paper presents some results of a measurement campaign in the service area of the digital terrestrial television (COFDM-8K system) experimental network of Madrid (Spain). The purpose of this survey has been to determine the degradation suffered by analogue PAL-G signals in the presence of co-channel and adjacent channel digital emissions. The result is a curve that estimates the protection ratios between analogue and digital received power levels.

Location correction factor for coverage planning tools for DRM (Digital Radio Mondiale) in the 26 MHz band

DRM (Digital Radio Mondiale) is the only digital radio system standardized for the high frequency bands. The traditional application of these bands is the broadcasting service by means of the ionospheric propagation to cover large areas at long distances. However, the 26 MHz band is nowadays scarcely used because it presents worse ionospheric propagation conditions than the lower frequencies, partially due to the 11 year period sunspot cycle. Nevertheless, some companies and research institutions have tested the possibility of using the DRM standard in these frequencies for local broadcasting due to the potential of this band for tropospheric (line of sight) propagation. New planning tools must be developed for this new application of the DRM future networks. This paper studies the signal spatial variability, an important parameter needed in the coverage prediction planning tools.