The STREAM X Multichannel GPR System: First Test at Vieil-Evreux (France) and Comparison with Other Geophysical Data ALEXANDRE NOVO 1 *, MICHEL DABAS 2 AND GIANFRANCO MORELLI 1 1 Geostudi Astier, Via Nicolodi, 48, Livorno, Italy 2 Geocarta, 5 rue de la Banque, Paris, France ABSTRACT A new multichannel ground-penetrating radar (GPR)system was tested at the Gallo-Roman site of Vieil-Evreux (Evreux, France). The resultant maps are compared with previous ones obtained with the ARP© system and oth standard geophysical techniques at the same site. Results show how full-resolution GPR data acquisition meth gies, together with a robust integration of navigation and positioning mounted on a vehicle for fast prospe the best results. The objective of this work was to present the results of the first test of the system STREA option for non-destructive prospection of large archaeological sites. Copyright © 2012 John Wiley & Sons, Key words: Ground-penetrating radar; multichannel; three-dimensional visualization; array system; ARP©; Roman sites Introduction Ground-penetrating radar (GPR) has been one of the most utilized tools for archaeological prospection in the past two decades (Conyers and Leckebusch, 2010) due to its high-resolution data and three-dimensional visualization capabilities. In particular, GPR has a successfulhistory in discovering Roman villasand towns (Neubauer et al.,2002;Leckebusch, 2003;Piro etal.,2003;Linford, 2004;Berard and Maillol,2008). Although full-resolution images can be generated with single-channel systems (Grasmueck et al., 2005;Novo et al., 2008) and can benefit the interpretation of subtle features over complex archaeological sites (Novo et al., 2012), the extra time needed for collecting this type of data has minimized its use. Therefore,the standard methodology is stillbased on coarse profile spacing data collection and subsequent interpolation to fill in the data gaps during three-dimensional processing (Novo et al., 2010). Small array systems using two antennae in parallel have shown a potential simple solution (Leckebusch, 2005).In fact, Grasmueck etal.(2010)were able of halve the time needed forobtaining full-resolution images with a self-developed system (Grasmueck and Viggiano,2007).However,the use of such modular array systems for full-resolution surveying in large- scale archaeological prospection stillpresentssome limitations (Verdonck and Vermeulen, 2011). The new generation ofmultichannelGPR instru- mentstry to solve the spatial sampling biaswhile speeding-up data acquisition. A paramount advantage of multichannelsystemsis that the full-resolution of GPR recording on the ground can be handled adequately by systems in which the antenna channel separation approaches distances close to a quarter of the wavelength of the transmitted wavelength of the central antenna frequency. These design characteristics have been accomplished by many of the current GPR manufacturers of multichannel systems. Even though the first introduction ofmultichannelGPR systems dates back more than 15 yr (Warhus et al., 1993),the complete acceptance of multichannelrecording was limited by the quality ofthe data and complex data processing (Franceset al., 2009).Wildly different frequencyresponsesof the multichannelantenna prevented useful amalgamation of the individual pro- files into useful images (Goodman et al., 2011). How- ever,in the past few years, most of the multichannel * Correspondence to: A. Novo, Via Nicolodi, 48, 57121 – Livorno, Italy. E-mail: novo@geoastier.it Copyright © 2012 John Wiley & Sons, Ltd. Received 21 February 2012 Accepted 8 July 2012 Archaeological Prospection Archaeol. Prospect. (2012) Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/arp.1426