[Acoustics] GPS Receivers

[David S. Mueller]

OSW staff have received several recent requests for recommendations on GPS
receivers for use with ADCP's.  Since there is some general interest in
this, we thought it might be good to share the following information
regarding GPS receivers for use with ADCPs.  

 

In the past we have suggested the Trimble AgGPS 132 or DSM 132, however, we
have experienced some minor issues with these receivers and with obtaining
information from Trimble. That is not so say these are not good and
acceptable receivers.  Over the years they have proven to be reliable and
generally trouble free.

 

Some of the issues we have run into with these Trimble models are:

1)   P/V Filter must be turned off. This filter will be automatically turned
on if a firmware update is applied.

2)   When no VTG data is available the unit will output a velocity of 0.00
rather than no data. 

3)   When GPS signal is lost the VTG sentence will continue to output the
last valid velocity, rather than no data.

4)   It has been impossible to reach support engineers who are willing to
discuss some of the filtering and behavior of the instrument with us.

 

Water Survey of Canada have been using Novatel receivers for several years.
Novatel now makes a Smart V1 Antenna that is a one-piece receiver. I have
used one of these during a training class in Ottawa and it seemed to work
very well. Details on the V1 can be found at:

 

http://www.novatel.ca/products/smartv1.htm

 

I have used a CSI Wireless Seres smart antenna one-piece receiver for
several years and have been very happy with it. CSI Wireless changed their
name to Hemisphere GPS a couple of years ago. The Seres is no longer
available but they now have an A100 Smart Antenna that appears to be the
next generation of the Seres. For details on the A100 see:

 

http://www.hemispheregps.com/Products/PrecisionProductsGroup/PrecisionProduc
ts/A100SmartAntenna/tabid/349/Default.aspx

While I don't have a lot of experience with the V1 or A100 they are what I
would purchase if I were purchasing a GPS unit for use with an ADCP. Both
units support WAAS differential corrections. The V1 also supports Omnistar,
if you use that subscription service.   

 

Regardless of what GPS receiver you purchase, be sure and read the manual,
configure the unit appropriately, and test the receiver before collecting
critical data.

 

Any use of trade, product, or firm names is for descriptive purposes only
and does not imply endorsement by the U.S. Government.

 

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

 

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