[Acoustics] Using a Streampro with GPS

Thu May 8 08:58:09 CDT 2008

We tried a compass that provides Heading (basically two antennas in a
single enclosure) and our very first results showed that under the
conditions where we typically measure (i.e. near bridges, shore edges,
tree canopies), the GPS acquisition conditions are less than adequate to
provide the data required for reliable results.  These were however
preliminary tests of such a GPS, but we did lots of GPS/ADCP testing and
chances are not too good for it.  We are not planning any more trials of
such system but please let us know if anyone has good news as this woudl
be a good way to get rid of magnetic interferences creating errors in
mmts via the flux gate compass...

F.
Francois Rainville 
Water Survey of Canada / Services hydrologiques du Canada 
Ottawa 613-992-1673 

________________________________

From: acoustics-bounces at simon.er.usgs.gov
[mailto:acoustics-bounces at simon.er.usgs.gov] On Behalf Of David S.
Mueller
Sent: Tuesday, March 18, 2008 12:13 PM
To: 'Tracy Vermeyen'; acoustics at simon.er.usgs.gov
Subject: RE: [Acoustics] Using a Streampro with GPS

Tracy,

You will need to use an external compass of some type, mounted on the
Streampro or on the boat, with the compass calibrated and aligned with
the coordinates of the Streampro.

A single antenna GPS will not help you. Successive measurements of
position will give you your course but not necessarily the heading of
the boat and instrument. There are GPS units available that come with
two antennas and these two antennas work together as a compass and
report a heading within 0.5 degree. I have one of these devices but
haven't tested it.

WinRiver II should take an external heading from either a compass, gyro,
or GPS compass.

David S. Mueller

Office of Surface Water

U.S. Geological Survey

9818 Bluegrass Parkway

Louisville, KY 40299

Office: (502) 493-1935

Fax: (502) 493-1909

Cell: (502) 558-5907

From: acoustics-bounces at simon.er.usgs.gov
[mailto:acoustics-bounces at simon.er.usgs.gov] On Behalf Of Tracy Vermeyen
Sent: Monday, March 17, 2008 5:08 PM
To: acoustics at simon.er.usgs.gov
Subject: [Acoustics] Using a Streampro with GPS

Hello,

I am considering using a Streampro transducer in a fixed mount on a
small Jon boat combined with RTK-GPS input to WinRiver II to collect
data in shallow backwater areas or during extremely low flows.  

I understand the limitations of the Streampro i.e. no compass or pitch
and roll sensors.  But I am not sure if bringing GPS into Winriver II
will overcome the no compass limitation and provide heading information
necessary to compute velocity in earth coordinates.  I think we can
minimize the pitch and roll errors, or at least live with the errors.

FYI, This project involves collecting data to verify a 2-D hydraulic
model to be used to evaluate fish habitat in a regulated river.

I was wondering if anyone has done this and how the data worked out?  If
the computations have to be done in post-processing I would like to know
how you did that.

Thanks for the help.

Tracy B. Vermeyen, P.E.                           
Hydraulic Engineer                      
Bureau of Reclamation                        
Hydraulic Investigations and Laboratory Services Group
P.O. Box 25007, 86-68460
6th and Kipling Street
Denver, Colorado  80225-0007

Phone:  303-445-2154
FAX :     720-544-0551 
Cell:       303-870-9178
e-mail: tvermeyen at do.usbr.gov 
http://www.usbr.gov/pmts/hydraulics_lab/tvermeyen/index.html

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