Block V: Receiver Array

For option W OASM will compute the plane wave replicas for the specified array. Matched field and other replicas are read from an external file of the format described in Sec. 11.4.2, and here the array geometry in Block IV is just used for consistency check. Note that such a consistency is not required for the covariance matrix file, which allows for simulation of array mismatch. The first line of this block specifies the number of sensors. Then follows the position, type and gain for each sensor in the array. The the sensor positions are specified in cartesian coordinates in meters. The types currently implemented are as follows

1.

Hydrophone. Normal stress (negative of pressure in water) in Pa for source level 1 Pa (or Pa for source level 1 Pa).

2.

Geophone. Particle velocity in x-direction (horizontal). Unit is m/s for source level 1 Pa (or m/s for source level 1 Pa).

3.

Geophone. Particle velocity in y-direction (horizontal). Unit is m/s for source level 1 Pa (or m/s for source level 1 Pa).

4.

Geophone. Particle velocity in z-direction (vertical, positive downwards). Unit is m/s for source level 1 Pa (or m/s for source level 1 Pa).

The gain is a calibration factor in dB which is applied to the replica on all sensors. When combining hydrophones and geophones in array processing it is important to note that there is a difference in order of magnitude of pressure and particle velocity of the order of the acoustic impedance. Therefore the geophone sensors should usually have a gain which is of the order 120 dB higher than the gain applied to the hydrophone sensors.