Multilingual search for cultural heritage archives via combining multiple translation resources

The linguistic features of material in Cultural Heritage (CH) archives may be in various languages requiring a facility for effective multilingual search. The specialised language often associated with CH content introduces problems for automatic translation to support search applications. The MultiMatch project is focused on enabling users to interact with CH content across different media types and languages. We present results from a MultiMatch study exploring various translation techniques for the CH domain. Our experiments examine translation techniques for the English language CLEF 2006 Cross-Language Speech Retrieval (CL-SR) task using Spanish, French and German queries. Results compare effectiveness of our query translation against a monolingual baseline and show improvement when combining a domain-specific translation lexicon with a standard machine translation system

Domain-specific query translation for multilingual access to digital libraries

Accurate high-coverage translation is a vital component of reliable cross language information access (CLIR) systems. This is particularly true of access to archives such as Digital Libraries which are often specific to certain domains. While general machine translation (MT) has been shown to be effective for CLIR tasks in information retrieval evaluation workshops, it is not well suited to specialized tasks where domain specific translations are required. We demonstrate that effective query translation in the domain of cultural heritage (CH) can be achieved by augmenting a standard MT system with domain-specific phrase dictionaries automatically mined from the online Wikipedia. Experiments using our hybrid translation system with sample query logs from users of CH websites demonstrate a large improvement in the accuracy of domain specific phrase detection and translation

Domain-specific query translation for multilingual information access using machine translation augmented with dictionaries mined from Wikipedia

Accurate high-coverage translation is a vital component of reliable cross language information access (CLIA) systems. While machine translation (MT) has been shown to be effective for CLIA tasks in previous evaluation workshops, it is not well suited to specialized tasks where domain specific translations are required. We demonstrate that effective query translation for CLIA can be achieved in the domain of cultural heritage (CH). This is performed by augmenting a standard MT system with domainspecific phrase dictionaries automatically mined from the online Wikipedia. Experiments using our hybrid translation system with sample query logs from users of CH websites demonstrate a large improvement in the accuracy of domain specific phrase detection and translation

Comparison between Galileo CBOC Candidates and BOC(1,1) in Terms of Detection Performance

Many scientific activities within the navigation field have been focused on the analysis of innovative modulations for both GPS L1C and Galileo E1 OS, after the 2004 agreement between United States and European Commission on the development of GPS and Galileo. The joint effort by scientists of both parties has been focused on the multiplexed binary offset carrier (MBOC) which is defined on the basis of its spectrum, and in this sense different time waveforms can be selected as possible modulation candidates. The goal of this paper is to present the detection performance of the composite BOC implementation of an MBOC signal in terms of detection and false alarm probabilities. A comparison among the CBOC and BOC(1,1) modulations is also presented to show how the CBOC solution, designed to have excellent tracking performance and multipath rejection capabilities, does not limit the acquisition process

Comparative Analysis of Acquisitions Techniques for BOC Modulated Signals

This work will address the analysis of acquisition schemes and algorithms useful for acquiring the Galileo BOC modulated signals and its performance. A modified acquisition strategy based on the Bump Jumping algorithm will be addressed. The impact of the side lobes (in terms of detection probability and false alarm probability) in different system conditions is evaluated. In order to compare the various acquisition systems and to identify the schemes that can be successfully used in the acquisition of Galileo signals, a simulation based analysis has been performed to identify the best strategy (and the relative parameters) that can work with the Galileo signal trading the receiver complexity with the expected performanc

Quality Monitoring for Multipath Affected GPS Signals

Abstract. The ability to monitor and detect any disturbances on the PRN code signals transmitted from the navigation satellite constellation is of primary importance. It is known that the tracking performance of a navigation receiver stems from the correlation property of the PRN code signals transmitted. These anomalies can be detected in several different ways, either observing the outputs of navigation user receivers, or processing the received signal within the receiver. Quality control is the process that defines how well the solution of a problem is known and in the context of navigation, it consists of assuring an agreed level of accuracy, reliability and robustness for the measurements. In this work a modified version of the conventional tracking scheme will be proposed with the aim of monitoring the quality of th

Efficient Signal Acquisition and Tracking for a Real Time GPS/Galileo Software Receiver

In a Global Navigation Satellite System (GNSS) receiver the acquisition algorithms as well as the signal tracking play an important role in the receiver functioning. When the receiver is implemented in software radio technology the demanding computational complexity becomes a critical issue as much as the algorithms performance and stability. This paper presents the solutions adopted for the signal acquisition and tracking for the N-Gene fully software receiver. The acquisition algorithm is a variant of the classical "fast acquisition algorithm" where the signal correlation is obtained in time domain by means of two Fast Fourier Transforms (FFTs) and a single Inverse Fast Fourier Transform (IFFT). A solution for improving the tracking performance in case of low C/N0, is also proposed. The work on the signal tracking focuses on a robust normalization of the discrimination functions within the tracking loops. The algorithms are presented highlighting case by case the advantages both in terms of computational complexity, robustness and performanc

Acquisition Performance Analysis for BOC Modulated Signals

The advent of the new European satellite navigation system Galileo and the current study of a new generation of GPS satellites are increasing the interest towards navigation related systems, services and applications. Both the systems foresee improved performances with respect to the present GPS C/A code, mainly achieved by using novel modulation schemes for the signals-In-Space. The Binary Offset Carrier (BOC) modulation, different (and longer) codes, and pilot channels have been proposed as a mean to reduce the mutual interference on common carriers, and also as a way to improve the expected performance. On the receiver side these system design choices have a relevant impact on the receiver architecture which as now to deal with different signals. One of the core techniques affected by these choices is certainly the acquisition stage, which has the goal to detect the presence of a certain satellite and to provide a rough estimation of the local code alignment and Doppler shift. This work will address the comparison of the acquisition schemes useful for acquiring the Galileo BOC modulated signals It is well known that several 1

Quality Monitoring for Multipath Affected Signals Using an Extended Kalman Filter

The ability to monitor and detect any disturbances on the PRN code signals transmitted from the navigation satellite constellation is of primary importance. It is known that the tracking performance of a navigation receiver stems from the correlation property of the PRN code signals transmitted. These anomalies can be detected in several different ways, either observing the outputs of navigation user receivers, or processing the received signal within the receiver. Quality control is the process that defines how well the solution of a problem is known and in the context of navigation, it consists of assuring an agreed level of accuracy, reliability and robustness for the measurements. In this work a modified version of the conventional tracking scheme will be proposed with the aim of monitoring the quality of the measurements at the signal processing level. The proposed tracking scheme is able to give a measure of the distortion of the correlation function and consequently, of the reliability of the signal tracked. In particular the problem of multipath distortion is considered The amplitude and multipath delay can be estimated with an extension of the linear Kalman Filter which can be implemented inside the traditional DLL architecture. Simulations show that due to its prediction capability, Kalman Filter enhances the robustness of the system when weak signals are present or there is loss of lock on the signals, trading off the performance improvement with an increase in complexity of the new architecture. The recognition of a multipath corrupted signal estimating the amplitude and delay of the reflection can be used to select the more reliable pseudo-range measurements for the evaluation of the positioning equations. Mitigation of the multipath effects may be performed where the number of tracked signals is not sufficien

Design of a Reconfigurable Low/Complexity Tracking Loop for Galileo Signals

The increased use of digital technology in communications is resulting in more functions of contemporary radio systems that are being implemented using a Software- Defined-Radio (SDR) approach [1]. The growing interest towards navigation applications, the advent of the European Navigation System Galileo and the new generation GPS, make the SDR approach an interesting perspective to develop a software reconfigurable receiver for positioning applications. Even if the present technology does not allow to totally implement a personal communications receiver, navigation terminals demand for less stringent processing and can be almost completely designed with software defined radio techniques. One of the basic function of a navigation receiver is the signal tracking of a CDMA modulated Signal-In-Space (SIS) broadcast by the satellites constellation (GPS or the future European Galileo). Better is the sequences alignment performed in this stage, better is the pseudorange measurements used for the user position triangulation. This paper discusses the digital implementation of a delay-lock-loop (DLL) tailored for navigation application where a fine synchronization is required, with the aim of keeping as small as possible the system complexity requirement for a software-defined implementation