NAVIGATION AND DATA ACQUISITION

The vessel was set-up for multibeam data acquisition and navigation with RESON PDS-2000 and COMM-TECH NAVPRO softwares. Two workstations were used forthe acquisition of

• (PDS-2000) multibeam data, interfacing by a multiserial and Ethernet link a RESON 8160 P1 processor, an TSS MAHRS MRU and FOG compass, DGPS receiver, by a MOXA Multi/serial I/O, TC/P and UDP network sockets;
• (NAVPRO) Microtecnica gyrocompass, Atlas Krupp's DESO echosounders, coring cable tension and the DGPS receiver, by a Digiboard Multi/serial I/O card.

The latter workstation also collected the navigational data every 5 minutes.

The MBES was the 50kHz, 126 0.5°, 150°aperture RESON 8160 (5000 m range). The sonar head is positioned on the ship's keel using a V-shaped steel frame. A sound velocity probe at the Sonar Head is interfaced directly to the MBES processor, thus providing the necessary real-time data for the beam-forming.

The datum WGS84 and the UTM, zone 35, were chosen for navigation and display purposes. Timing was set to UTC for data acquisition. The PDS-2000 production DTM was set to grid sizes ranging from 1 to 15-20m. The SBP-CHIRP workstation received positions trough an NMEA sentence by the DGPS receiver. The positions were therefore recorded on the XTF trace headers as lat/long of the DGPS antenna.

The instrumental offsets (PDS-2000) are presented in Fig. 14 and in Tab. 3

Table 3: Instrumental Offsets on Ship Urania (PDS2000). The GPS antenna (primary positioning system) is located on point DGPS.

POSITION	ACROSS	ALONG	HEIGHT
REFERENCE	0.00	0.00	0.00
DGPS	1.64	14.30	14.18
MBEAM	0.00	14.36	-4.96
MAHRS	0.00	0.0	-3.40
CHIRP	-1.0	11.80	-4.00
CORER	6.5	-6.70	0.0
STERN	0.00	-30.60	0.00
STERN-LEFT	-4.00	-30.60	0.0
STERN-RIGHT	4.00	-30.60	0.0
GI-GUN ARRAY	4.0	-48.0	0.0
FIRST ACTIVE 48CH	0.0	-168.0	0.0

figure

Figure 14: Cruise MARM05. Instrumental Offsets (PDS-2000) on R/V Urania