M.M. Velez

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.

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.

MIMO Performance of the Next Generation DVB-T

This paper analyses the performance of a DTT (digital terrestrial television) broadcasting system that includes MIMO-OFDM techniques. The benefits of these techniques are studied comparing the results for different MIMO 2 x 2 (multiple input multiple output), MISO 2 x 1 (multiple input single output) and SISO (single input single output) system configurations. Different propagation channel models and configurations are considered for each diversity scheme. This study has been carried out in the context of development of the next generation DVB-T, called DVB-T2.

DVB-T BER measurements in the presence of adjacent channel and co-channel analogue television interference

This paper presents some laboratory tests carried out to measure the BER degradation caused by an analogue PAL-G television interference on a COFDM 8 K digital television signal. The tests made include co-channel and both upper and lower adjacent channel interference situations. Previously, the ITU-R has presented some protection ratios to be sought when planning DVB-T networks. The results of the work presented here include a wider range of power ratios and their effect on the BER rather than the limit protection values. The new digital services will share the same frequency bands as the conventional analogue television so the exact characterization of mutual interference is a major concern of broadcasters during the transition period when both systems have to co-exist.

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.

Use of the Channel Impulse Response of the DVB-T Service for the Evaluation of the Reflected Signals of Wind Farms

Wind turbines can cause degradation to the existing transmission systems, especially in the analogue television terrestrial broadcasting and radar services. The main effects of the interference are caused by the reflected signals in the support tower and in the rotating blades of the wind turbines. Empirical trials are necessary in order to adequately characterize the influence on the quality of the transmitted services, and to determine the parameters involved. The existing techniques to evaluate this influence are cost prohibitive or do not offer the required accuracy. In this paper, a low cost technique for evaluating the reflected signals from wind turbines is proposed, based on the analysis of the channel impulse response of the digital terrestrial television services. The results show that this technique provides accurate and reliable results.

DVB-T2 modulator design supporting multiple PLP and auxiliary streams

This paper presents the design of a DVB-T2 modulator algorithm supporting multiple PLP and auxiliary streams. The algorithm works over an asynchronous modulator design, presenting per stream scheduling policies, T2 Frames capacity management, and DFL computation. A software tool was developed in order to create system configurations, validate input parameters, and manage per stream capacity distribution, according to proposed scheduling policies.

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.

Analysis of the electric field strength location variability in the UHF band for mobile and portable multimedia broadband services in SFN networks

This paper describes the location variability of the received field strength derived from the statistical analysis of data obtained during a set of tests carried out in the cities of Bilbao and Madrid. The systems and services referred in this study are those ones operating in UHF band, specifically in TV Bands IV and V (470 – 860 MHz). Their evaluation has been based on the empirical references of standards originated inside the DVB (Digital Video Broadcasting) Consortium. Nevertheless, the obtained results can be extrapolated to the deployment of other standards operating in similar frequencies with a comparable bandwidth such us MediaFlo, ATSC M/H and so on. The main conclusion of this work is that the current values recommended by ITU-R and ETSI are pessimistic for SFN and MFN scenarios, different reception environments and digital terrain database granularities sizes below 100 meters (“small areas” according to the planning procedures). In that case, the standard deviation of the received field strength values is always lower than 3 dB.