Trimble SCS900 Hydrographic extensions

Users of Trimble Construction SCS900 software are now able to easily measure water depth and execute accurate small-scale hydrographic surveys. Ohmex Ltd has made use of the SCS900 Software Developers Kit (SDK) to produce a software utility that runs on the controller and supplies depth data to SCS900. This increment in functionality further enhances the use of the SCS900 system on marine construction sites where dams or waterways are present.

The concept of the Sonar extension to SCS900 is to enable the construction user to execute simple Hydrographic surveys using their SCS900 software together with existing positioning equipment, no need to learn another package or convert to new reporting facilities, the sonar effectively behaves as an extension to the existing survey detail pole for measuring water depth. The software is an inter-application package with both the SCS900 and SonarMite applications running concurrently on a TSC2, Tablet or PC platform. For evaluation purposes the SonarMite application has a 'Simulator' mode that generates sine wave data without the need for a SonarLite echo sounder to be connected ...

Trimble SCS900 Site Controller Software calculates position data in conjunction with the ATS Total Station, 5605 DR200+ Total Station, SPS700 Total Station, SPS780 and SPS880 Smart GPS Antennas, SPS750 and SPS850 Modular GPS Receivers, and SPS770 GPS Receiver. Developed by Trimble the SCS900 Extension SDK (software developers kit) enables software engineers to link third party sensors to the existing position data. The first system integrator to apply this link was Ohmex Instruments, a manufacturer of portable shallow water echo sounders for water depth measurement.

The SonarMite complements SCS900 by providing easy-to-use functionality for measuring water depth. Users no longer need to be a trained hydrographic surveyor to carry out this type of work, as the operator would be familiar with SCS900 and would simply add the echo sounder into the process. Users can leverage their existing Trimble SCS900 software and positioning equipment, with no need to learn another software package or convert to new reporting facilities. Since the SCS900 supports both Precision GPS and Robotic Total Stations, this system can be used in both open areas and in GPS-limited areas such as under bridges.

SCS900 Extension Module Drivers

A new feature of the SonarMite XP, Vista and Mobile software are extension module interface drivers to the popular SCS900 construction software from Trimble. These drivers enable the user to interface a water depth measurement to the position measurements within a machine control environments. Uses include many applications within the areas of marine and civil engineering.

SCS900 v2.8 - Ohmex Extension module

SonarMite v3.1 application software - SCS900 version

Both the PC and PDA versions of the software have been updated to facilitate updates of operating systems (Windows 7 and Windows Mobile 6).

Modifications to QA filter settings

It was found the QA settings were previously set a little tight for reliable collection of data. The settings were made on the basis that reliable data would be required under the following conditions ...


SCS900 would be used in turbid water conditions in a construction environment.


It would be unlikely the software would be used in depths greater than 25m.

As there were several situations in which this was not the case and data was filtered out the QA filter slider has been modified for a wider range of operation and that a windows error beep is also sounded if data fails to pass the filter settings. Previously the slider filter point ranged from QA values 80 to 110, the new settings are set for a range of 40 through to 100.

Explanation of the QA value

The QA value is a numeric representation of the inverse gain applied to the sonar transmission in order to maintain minimum beamwidth. In simple terms more power has to be applied in bad conditions to achieve the same return. The value of this number is complex and depends on several parameters ...


Turbidity - Quality of water in the column under the transducer.


Relection – The ‘hardness’ of the bottom surface.


Sound Velocity – The transmission speed of sound in water.


Depth – The total depth the sound has to travel through the water.

Auto enumeration of COM: ports.

The PC software has been modified to detect and auto enumerate com ports when making a serial connection to the SonarMite. This gets over the technical problems with port numbers greater than 10 in Winows Vista and Windows 7. The PDA version is still limited to ports COM1 to COM10.


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