5 th Meeting on Italian Antarctic Glaciology 2005 I talian RES I nvestigation in Antarctica: The New Radar System I.E. T ABACCO 2 , C. BIANCHI 1 , J.B. AROKIASAMY 1 , L. CAFARELLA 1 , U. SCIACCA 1 , A. ZIRIZZOTTI 1 & E. ZUCCHERETTI 1 1 Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Roma - Italy 2 Dip. Scienze della Terra, Sez. Geofisica, Via Cicognara 2, Milano - Italy *Corresponding author (ignazio.tabacco@unimi.it) THE I TALI AN RADI O ECHO SOUNDI NG SYSTEM A Radio Echo Sounding (RES) system is an active remote-sensing instrument that uses electromagnetic wave penetration into the ice to obtain information on the depth of the bedrock and on the ice thickness and its inhomogeneities, i.e. internal layering of glaciers and subglacial lake exploration. In 1995 the INGV developed its own airborne radio echo sounding system, which is continuously being upgraded. During the 1995, 1997, 1999, 2001 and 2003 Italian Antarctic Expeditions, the RES system was used to investigate different Antarctic regions. During 2007-2008 campaign, new RES systems will be used. In the following the main characteristics of the systems will be briefly described. THE OLD SYSTEM During the 1997 and 1999 Italian Antarctic Expeditions, the RES system developed at the INGV was placed on an aircraft flying 1000 feet above the ice surface; two folded dipole antennas, one for transmitting and the other for receiving echo pulses, were mounted beneath the aircraft wings (Tabacco et al., 1999; Bianchi et al., 2001). This airborne radio sounding system operated at 60 MHz with a pulse length of 0.3 μs -1 μs in 1997 and of 0.25 μs - 1 μs in 1999. The maximum delay of the received signal was 51.2 μs in 1997 and 64 μs in 1999, corresponding to a maximum penetration depth into the ice of about 4.3 km in 1997 and 5.3 km in 1999. The RF pulsed generator used a Phase Lock Loop (PLL) frequency synthesizer which allowed fine frequency corrections, thereby preventing mismatches due to the reflected peak power from the folded dipole antenna. The 4 kW transmitted power allowed us to obtain an adequate amplitude echo signal at the receiver. The receiver consisted of a solid-state low-noise Log envelope detector. The dynamic range of the receiver was 80 dB, and the received echo signal was digitised (8 bit) at a 20 MHz sampling frequency to obtain a temporal precision of about 50 ns. A Trimble 4000 SSE GPS system receiver with antenna mounted on the aircraft fuselage was installed and linked to the radar. Navigation relied on an onboard GPS receiver which recorded the longitude, latitude, altitude and time of acquisition Terra Antartica Reports 2008, 14 , 213-216 © Terra Antartica Publication