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The premise of reciprocal acquisition geometry is intimately related to
symmetric data acquisition.
The idea of symmetric wave field sampling was described by Ongkiehong
and Vermeer 
.
Their recommendation is to record seismic data as generally
as possible and perform
data reduction later, in the processing step. Array forming is thus done
not in the field but on the computer. This method, of course,
requires sufficient
dynamic range of recording equipment, but does not discriminate
against propagation effects.
(vector) source throughout the survey we must have a (vector) receiver
Figure 
and are examples of nearly reciprocal
data acquisition.
With the exception of the
source gap, the acquisition geometry is regular. Each source is located
between a receiver
position. Figure and represent the symmetric
and antisymmetric components of a time slice through the prestack data set.
Source and geophone positions were linearly interpolated
before
determining the amount of symmetry and deviation. The surprising result is
that the symmetric part and the antisymmetric part are about the same magnitude.
One would not expect this if one thought that equation 2 holds
for this data set. The lack of symmetry (or reciprocity) demands some
explanation. I chose to explain it by differences in source behavior,
assuming that differences in receiver behavior are small compared to the
potentially nonlinear behavior of seismic sources. The lack of symmetry
can be employed to set up a minimization problem, where the objective function
maximizes symmetry in a source-location and source-component consistent way.