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Block VI: Receivers

The default specification of the receiver depths is the same as for SAFARI, i.e. through the parameters RD1, RD2 and NRD in Block VI, with

RD1
Depth of uppermost receiver in meters
RD2
Depth of lowermost receiver in meters
NRD
Number of receiver depths

The NRD receivers are placed equidistantly in the vertical.

Non-equidistant Receiver Depths

In OASES the receiver depths can optionally be specified individually. The parameter NRD is used as a flag for this option. Thus, if NRD < 0the number of receivers is interpreted as -NRD, with the individual depths following immidiately following Block VI. As an example, SAFARI FIPP case 2 with receivers at 100, 105 and 120 m is run with the following data file:

SAFARI-FIPP case 2.
V H F O			       # Complex frequency integration. 
5 0
4
  0    0     0 0   0   0   0
  0 1500     0 0   0   1   0
100 1600   400 0.2 0.5 1.8 0
120 1800   600 0.1 0.2 2.0 0
95
100 100 -3                     # 3 receivers
100.0 105.0 120.0              # Receiver depths in meters
300 1E8                      
1024 1 950 0
2048 0.0 12.5 0.006 0.5 0.5 5

The PP Post-processor is compatible and will depth-stack the traces at the correct depths.

Tilted Receiver Arrays

The new option `T' allows for specification of an array tilt in the vertical plane containing the source and the receivers.

The tilt angle and rotation origin is specified in the receiver depth line (Block VI):

Standard For option T
RD1 RD2 NR ZREF ANGLE

The vertical arrays are rotated by an angle `ANGLE' in deg relative to the vertical. The rotation is performed with origin at depth `ZREF'.

The parameters RD1, RD2 and NR always refer to the untilted case. In the tilted case these parameters do therefore define the array geometry and not the actual depths of the receivers in the tilted array. The same is the case for the graphics output produced by the post-processor PP.

The source(s) is always at the origin and is therefore not rotated. Thus, for zero-offset tilted VSP-s, the reference depth ZREF should be set equal to the source depth SD!


next up previous contents
Next: Block VII: Wavenumber integration Up: Block II: OASP options Previous: Block V: Sources
henrik schmidt
1999-08-25