The conventional calibration method usually uses the classic input/output referred offset model, in which the receiver IF programmable gain amplifiers (PGAs) have offset sources that varies a lot with different gain settings.
The following ionization parameters were used: polarity, ES+; capillary, 30 kV; source temperature, 100 °C; sampling cone, 80; source offset, 80; source gas flow, 0 ml min−1; desolvation temperature, 300 °C; cone gas flow, 0 l h−1; desolvation gas flow, 600 l h−1; nebulizer gas flow, 6 bar.
In ES−/ES+ section: source capillary, 2.8 kV; sampling cone, 30; source offset, 60; source temperatures, 120 °C; desolvation temperatures, 450 °C; cone gas flow, 50 L/h; desolvation gas flow, 800 L/h; high-purity helium (He) as collision gas, high-purity nitrogen (N2) as nebulizer and auxiliary gas.
This file is sufficient for some observations, but if the field contains multiple sources or if the source is offset, both source and background extraction regions may need to be customized.
Electrospray conditions were capillary voltage 2.0 kV, cone voltage 30 V, source offset 60 V, source temperature 120°C, desolvation temperature 550°C, cone gas 20 l/hr, and desolvation gas 900 l/hr.
Then, numerical modeling is applied for building the relationship between the minimum depth of investigation and various properties, including resistivity of the earth, offset, and source length.
where (k_{h_z}) refers to the vertical offset between source and receiver wavefields (Biondi and Shan 2002).
Because of the offset, the source road might on average be farther away from the homologous road than from the "wrong" second road, i.e. the one that is running parallel to it in close vicinity.
A further complication that arises with this method is the need to offset the source distributions along the airfoil area between the two free shear layers by adding a pressure jump to the panel stations situated on this separation region.
A zero-offset source comparison was also conducted to assess the use of different impulsive sources for future VSP surveys in similar settings.
