Has anyone completed a hydrographic survey using typical GNSS equipment with Carlson field controller and integrated sounder? ?ÿI see the sounder option in SurvPC but have never done it. What did you use? ?ÿWhat sounder? ?ÿHow did it connect? ?ÿ How did you add difference from sounder to ARP of antenna? ?ÿDid you use network corrections or on site base/rover? ?ÿ
I assume the sounder continuously updates the height of rod field in SurvPC? ?ÿDid you just auto topo gobs of ground shots that you then created a dtm using standard modeling software??ÿ
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Would love to know more about your experiences.
Thanks. CB.?ÿ
RTK-GNSS to SurvCE on DC. Lowrance HDS Gen 3 sounder, spitting NMEA depth data via BT to SurvCE on the DC. SurvCE constant rod height (the height to the transducer). Records X,Y,Z with Z being the elevation of the seabed, calculated by SurvCE as the elevation of the transducer minus the depth from the sounder.?ÿ
This is a home brew kit, and there are many tricks to getting to work. In hindsight I'd probably get a proprietary black-box kit. However, the Lowrance has sidescan which is sweet - you get a picture of what you are surveying.
Most output a NMEA data stream to the controller, either via cable connection or bluetooth. As Richard mentioned, the depth is sent to the controller, where it is then added to the rod height (usually measured up from the transducer). Most controllers will record just the depth as well so you can output just those if desired.
We have a marine services division for more complex hydro work, so our crews typically run a basic single-beam system. When I used to do this sort of thing, it was with the Hydrolite from Seafloor.
Like most of the basic units, it is turnkey.
Once you have figured out how to connect the controller, and set the correct NMEA output format, it is simple - turn on the echosounder, start an RTK survey, pick the hydro measurement option or survey style, and start measuring. Usually the sounder just keep sending depths, and when a point is observed the controller uses the value sent at that epoch.
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