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Receiver location in SEGD

Posted: Wed Mar 03, 2021 2:45 pm
by gfname
SEG-D standard ... rev2.1.pdf (page 8) states that "Receiver positions are defined by a Receiver Line Number (three integer bytes and two fraction bytes), a Receiver Point Number (three bytes integer and two bytes fraction), and a Receiver Point Index (one byte). This index allows for defining the receiver group in the grid, the original value is 1 and that value is incremented by 1 every time the receiver is moved, even when it is moved back to the previous location". Similar statements are found for source position as well.

To me, a receiver position on surface is adequately defined by a line number and a point number. So what is a Receiver Point Index? How does it matter in positioning a receiver? Am I missing some concepts in seismic acquisition design?

Also, it seems there is no corresponding definition in SEG-Y.

Re: Receiver location in SEGD

Posted: Thu Mar 04, 2021 7:20 am
by Michael_Seman
If you only worked in the desert and the geophones were planted across a claypan and never disturbed, it may seem odd. But in transition zone survey, cables may be sloshed around by surf, so the receiver point index is used to indicate that the receiver is not in the same place it was yesterday. SPS files also allow for "receiver point index".

Re: Receiver location in SEGD

Posted: Thu Mar 04, 2021 3:15 pm
by gfname
Thanks for the explanations, Michael_Seman. It makes sense now.

Re: Receiver location in SEGD

Posted: Wed Mar 31, 2021 5:31 am
by AstridWilma
Do you guys have a link to more info. I'd like this a little bit elaborated.