# VMT_FilterBS

## PURPOSE

This routine filters the backscatter data.

## SYNOPSIS

function A = VMT_FilterBS(z,A)

## DESCRIPTION

     This routine filters the backscatter data.

     (adapted from code by J. Czuba)

     P.R. Jackson, USGS, 12-9-08

## CROSS-REFERENCE INFORMATION

This function calls:

This function is called by:

- VMT_PreProcess This function is a driver to preprocess the transects data. Several

## SOURCE CODE

    0001 function A = VMT_FilterBS(z,A)
    0002 % This routine filters the backscatter data.
    0003 %
    0004 % (adapted from code by J. Czuba)
    0005 %
    0006 % P.R. Jackson, USGS, 12-9-08
    0007
    0008
    0009 %% Filter
    0010 % filter backscatter when climbing walls
    0011
    0012 for zi = 1 : z
    0013
    0014     A(zi).Clean.backstandf=nan(double(A(zi).Sup.nBins),A(zi).Sup.noe);
    0015     A(zi).Clean.bsf=nan(double(A(zi).Sup.nBins),A(zi).Sup.noe);
    0016
    0017     % Determine the standard deviation of the backscatter for the four beams in
    0018     % one bin in one ensemble
    0019     back=A(zi).Wat.backscatter;
    0020     back(back>=255) = NaN;
    0021     A(zi).Clean.backstandf = std(back,0,3);
    0022
    0023     % Remove backscatter intensities >= 255 (bad value) and backscatter
    0024     % intensities with a standard deviation greater than 10 (mainly climbing
    0025     % walls)
    0026     A(zi).Clean.bsf = nanmean(A(zi).Wat.backscatter,3);
    0027     A(zi).Clean.bsf(A(zi).Clean.bsf>=255) = NaN;
    0028     %A(zi).Clean.bsf(A(zi).Clean.backstandf>10)=NaN;  %Removed STD screening PRJ 2-15-11
    0029
    0030     A(zi).Nav.depth(A(zi).Nav.depth==-32768)=NaN;
    0031
    0032 end