OTT SVR 100 X-Series Integration Guide

The OTT SVR 100 Surface Velocity Radar Sensor is designed for measuring flow in open channels and rivers. The sensor is compatible with NexSens X-Series data loggers utilizing the SDI-12 communication protocol and sensor interface. Parameter data is transmitted, in real-time, at a user-specified interval (e.g., 10 minutes) to the NexSens WQData LIVE Web Datacenter. There, data is stored on customizable dashboards with statistics and graphical interfaces for each parameter. Users can download and send data reports via Email, FTP, or an API. Below is information on the settings and wiring required to integrate OTT SVR 100 Surface Velocity Radar Sensors with NexSens X-Series data loggers.

OTT SVR 100 Surface Velocity Radar Sensor product page.

Figure 1: OTT SVR 100 Surface Velocity Radar Sensor integration with NexSens X-Series data loggers.




Compatible Models

OTT provides a single model of the SVR100 that is compatible with NexSens X-Series data loggers. Measurements collected by the sensor are based on the physical Doppler effect. A radar pulse is emitted at a 24.2 GHz frequency and is reflected from particles moving on the water’s surface. If the water is moving, the radar pulses are reflected with a slight frequency shift that can then be calculated as the surface velocity.



OTT SVR 100 Surface Velocity Radar Sensor product page.

Figure 2: OTT SVR 100 Surface Water Velocity Radar Sensor



Sensor Integration

Using the CONNECT software, a generic SDI-12 script can be generated to provide communication between the logger and sensor at a user-specified interval. The only settings that may require adjust is the SDI-12 address to ensure it is unique from all other connected sensors.

1. Wiring

NexSens can provide a connectorized UW8 plug on the end of the OTT SVR 100 factory cable for integration with an X-Series data logger, or a UW8 to flying lead cable may be utilized for wiring into a junction box. The following table refers to the latter application.

NexSens UW8 Plug PinNexSens UW8-FLx Wire Color*SignalOTT Sensor Cable Wire Color
2BlackGroundGrey & White
5Red12V PowerBrown

*NexSens UW Plug to Flying Lead Cable

Figure 3: NexSens UW8 Plug pin numbers.



2. Configure Communication

An RS-232 USB cable with a separate external power source may be utilized for communication with the OTT SVR 100 sensor in the OTT SVR 100 Operating Program. Default SDI-12 settings do not need to be changed for communication with the X-Series data logger. This operating program allows for viewing real-time data and changing the following settings:

  1. Device SDI-12 address
  2. Filter Type
  3. Filter Length
  4. Radar Sensitivity
  5. Flow Direction Filter
NexSens RS-232 USB Cable Wire ColorSignalOTT Sensor Cable Wire Color
YellowRS-232 TxGreen
OrangeRS-232 RxYellow
BlackGroundWhite & Grey

*No external power source should be connected to the USB cable.
**An external power source must be utilized to provide between 9-27VDC to the sensor. Ensure that the external power source has a common ground with the USB cable and OTT sensor cable.


3. Automatic Sensor Detection

The user must create a Generic SDI-12 script through the NexSens CONNECT software to communicate and gather measurements from the sensor. The user must reference the SDI-12 address and parameters output by the sensor for proper configuration. Follow the link below to review the process for creating a Generic SDI-12 script through the CONNECT Software:

SDI-12 Script Generation

The Generic manufacturer and SDI-12 model must be selected in the SDI-12 script utility. The measurement command should always be ‘C’, which allows for measurements to be obtained concurrently with other SDI-12 sensors connected to the logger. Switch power provides a balance between power consumption and data accuracy. SDI-12 sensors require a specific warmup time depending on the number of parameters to be measured. Determine the appropriate warmup time by communicating with the sensor in the CONNECT SDI-12 Tool:

ManufacturerModelSDI-12 AddressPortWarmupMeasurement CommandPower
GenericSDI-120-9 (Default = 0)P0, P1, or P2At least 5 seconds longer than the sample durationCSwitch


Parameter List from C Command

The default parameter list for the sensor is below. Match the parameter output below in the script.

CONNECT Parameter NameUnitsOTT SVR 100
Parameter Name
Velocitym/sMean Velocity of FlowAverage flow velocity over approximately 30 seconds.
Velocitym/sCurrent Velocity of FlowCurrent flow velocity.
Parm 01degSensor Tilt AngleInclination relative to the water surface. Optimal range is between 30 and 45 degrees.
Parm 02Signal Quality IndexQuality of radar signal received for measurement.

0 – Good Signal
3- Very bad signal

Parm 03Vibration IndexMeasure of vibrations in deployment area.

0 – No vibration
3- Very strong vibrations (Data unacceptable)

SNRdBSignal-to-Noise RatioMeasure of desired radar signal to the level of background noise.

>6 – Good signal


Run the Sensor Detection

Once the script is created, transfer and enable it on the data logger.

Configure Sensor Scripts

After the script is enabled, run a sensor detection to program the sensor onto the logger.

Run a Sensor Detection


Read Sensor Configuration – Confirm Sensor Detection

After ~5-10 minutes, read the sensor configuration to confirm the sensors have been detected on the data logger. Thoroughly review the parameter list to ensure all parameters are accounted for and are measured in the desired units. Let the unit gather a few readings to confirm accurate and reasonable parameter data.

Read Sensor Configuration


4. Setting up WQData LIVE

Once an X-Series data logger has finished a new sensor detection, it will automatically push the sensor configuration to the WQData LIVE Web Datacenter. Follow the three articles below to create a WQData LIVE account and a project/site. Then add the data logger to the project using the included claim code.



Real-Time System Application

Real-time surface velocity measurements from the OTT SVR 100 Surface Velocity Radar Sensor are useful in various environmental monitoring applications.

Applicable Systems

Discover applicable uses for the OTT SVR 100 Surface Velocity Radar Sensor.

Case Studies

Read about specific applications using the OTT SVR 100 Surface Velocity Radar Sensor.

Sensor Manual

For additional information on the OTT SVR 100 Surface Velocity Radar Sensor, please refer to the OTT SVR 100 Surface Velocity Radar Sensor Manual.