RESOLVE

Fig. 184 A RESOLVE system in operation. A base station is also deployed for DGPS and magnetometer. Source: USGS.

RESOLVE is a frequency-domain multi-coil system operated by CGG. The system has evolved over years, but here we describe the basic specification of the system based on RESOLVE III system.

Coils

Table 6 : RESOLVE III system specifications

Frequency (Hz)	400	1.8k	3.3k	8.2k	40k	140k
Configuration	HCP	HCP	VCA	HCP	HCP	HCP
Separation (m)	7.86	7.86	8.99	7.86	7.86	7.86

The system consists of six pairs of coils operating at six discrete frequencies and in horizontal coplanar (HCP) or vertical coaxial (VCA) configurations as listed above. The actual operating frequencies can be slightly different from the nominal frequencies in the table.The relative geometry of the coils are illustrated in Fig. 185. The measured data is the secondary magnetic field (Hs) normalized by the primary field (Hp) in part per million (ppm).

Fig. 185 A RESOLVE bird and the coils.

Flight

RESOLVE has a nominal terrain clearance of 30 m and a nominal aircraft speed of 30 m/s. The aircraft is positioned using post-processed differential GPS in processing, and real-time satellite differential GPS in flight. A typical sampling rate of data is 10 Hz (approximately 3 m sounding spacing).