mbm_rollerror
Section:  MB-System 5.0  (l)
Updated:  4 January 2001 
Index


 
NAME

mbm_rollerror - Macro to read a swath sonar bathymetry file, calculate the noise in the vertical reference used by the sonar, and generate a file containing roll corrections which can be applied to the data.

 
VERSION

Version 5.0

 
SYNOPSIS

mbm_rollerror -Fformat -Ifile [-Wfilterwidth]

 
DESCRIPTION

mbm_rollerror is a macro which generates crosstrack slope
corrections from the apparent vertical reference noise of swath sonar
data.  The crosstrack slopes are obtained by running
mblist. The resulting time series is filtered using the GMT
utility filter1d, which uses a time domain median filter with
a time width of 5 minutes.  The filtered signal contains little of
the actual bathymetric signal, and thus represents a combination of
noise in the seafloor reflection travel times and the vertical 
reference data stream.  Close inspection of Hydrosweep data collected 
on the R/V Ewing with an interactive editor (mbedit) reveals
clear variability in the observed crosstrack slope, even when
surveying essentially flat seafloor.  This suggests that the filtered
signal is probably dominated by vertical reference noise on the Ewing.
The corrections can be applied to Hydrosweep data during the calculation
of bathymetry from travel times using mbbath.

 
AUTHORSHIP

 
AUTHORSHIP

David W. Caress (caress@mbari.org)




  Monterey Bay Aquarium Research Institute



Dale N. Chayes (dale@ldeo.columbia.edu)




  Lamont-Doherty Earth Observatory



Suzanne H. O'Hara (sohara@ldeo.columbia.edu)




  Lamont-Doherty Earth Observatory

 
OPTIONS


-F


format



Sets the format for the input swath sonar data using 
MBIO integer format identifiers. 
This macro uses the MBIO library and will read any swath sonar
format supported by MBIO. A list of the swath sonar data formats
currently supported by MBIO and their identifier values
is given in the MBIO manual page.
Default: format = 24.
-I


file



Data file from which the input data will be read.
-W


filterwidth



Sets filter width in seconds. Default: filterwidth = 60.


 
EXAMPLES

Suppose one has obtained a Hydrosweep DS swath sonar data file 
called hs_ew9302_157_bcen.mb24 in the
L-DEO binary in-house format (format id 24). In order to generate a 
slope correction file:



       mbm_rollerror -F24 -Ihs_ew9302_157_bcen.mb24 




The output will be in a file called hs_ew9302_157_bcen.mb24.cor

 
SEE ALSO

mbsystem(l), mblist(l), mbbath(l)

 
BUGS

So far it is pretty rare for this utility 
to significantly improve bathymetry data 
(but occasionally it happens!).



 
Index

NAME

VERSION

SYNOPSIS

DESCRIPTION

AUTHORSHIP

AUTHORSHIP

OPTIONS

EXAMPLES

SEE ALSO

BUGS

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