SUKDMDCR, SUKDMDCS	


Downward continuation of sources and/or recievers using Kirchhoff Data
Mapping method.  SUKDMDCR extrapolates receivers given common-source
gathers, SUKDMDCS extraploates sources given common-receiver gathers.
These codes are first generation codes of this type, in that they are
kinematically correct in heterogenous models using ray tracing travel
times, but assume constant background wavespeed for amplitude calculations.
Thus, they are 2.5D true-amplitude in constant wavespeed media, but only
approximate in other models.  A full integral expression for the process
in heterogenous media is published, but these codes only implement the
constant wavespeed form of the integral for amplitude determination. 

These simple demos assume horizontal recording and datuming surfaces,
however, the codes do allow for topographic variations on both of these
surfaces (see selfdoc for codes).  


Demo 1 - Downward continuation of receivers on a single shot gather.

This demo demonstrates the basic parameters required to use the codes,
by downward continuing just the receivers on a single shot gather, from
a horizontal recording surface at z=0m to a horizontal datum surface at
z=300m.  The data is generated for a single horizontal reflector at 
z=1500m in a constant wavespeed medium.  The demo script is general
enough to use as a template for more complex models, though.

DataDemo1  -  Generates data for a single shot gather for the demo.
DCDemo1    -  Performs the downward continuation of receivers, and 
              displays the output. 


Demo 2 - Downward continuation of an entire survey (both receivers
and sources). 

This demo generates a set of data with 25 shot gathers, each with
100 receivers, again for a constant wavespeed medium with a horizontal
recording surface over a single horizontal reflector at 1500m depth.  
Then both the receivers and the sources are downward continued to a
new datum at 300m depth.  As in the first demo, the script for this
simple example is general, so that it can be used as a template for
more complex situations.

DataDemo2  -  Generates survey data for the demo.
DCDemo2    -  Performs downward continuation of receivers then
              resorts and extrapolates sources.
XDCDemo2   -  View input and output shot gathers for Demo 2. 

Additional files:

Clean      -  Removes data and output files from both demos
vel.mod    -  velocity model file for demos (do not remove)

If you have further questions, please contact:

John Stockwell	 | jstockwe@mines.edu
Center for Wave Phenomena (The Home of Seismic Un*x)
Colorado School of Mines
Golden, CO 80401 | http://www.cwp.mines.edu/cwpcodes
voice: (303) 273-3049  |    fax: (303) 273-3478.
