Salinity, Conductivity, Temperature and Depth Logge

Small and economical salinity logger. Easy to mount on gear.
For use on subsea gear and moorings for long-term oceanographic studies. Adding Star-Oddi’s protective housing offers flexible mounting options and added protection.

Key Features

Smallest CTD salinity logger on the market
Flexible mounting with protective housing
Different ranges, high or low conductivity
Depth sensors for shallow to deep ocean
On/off saltwater switch for saving memory


Smallest CTD on the market
This small autonomous salinity probe DST CTD measures and records conductivity, temperature and pressure. In addition to the three measured parameters the software calculates and displays salinity values and velocity in graphical and tabular form upon data conversion. It is only 50 mm in length and 15 in width. Due to its small size it is easy to mount it on various gear and nets.

DST CTD is small and economical when compared to bulkier CTDs on the market. The CTD salinity measuring device is used for a variety of studies including:

Oceanography and hydrography – long term stationary monitoring or surveying
Fisheries research – CTD attached to fishing gear
Data collection on underwater vehicles – small sized CTD is an advantage.
For using the CTD on fish and marine animals, click here.
Flexible mounting with protective housing
A plastic protective housing is available, recommended when fastening the logger to subsea gear and moorings.

Depth sensors for shallow to deep ocean
Customers choose between depth calibration ranges up to 100 m, 500 m, 1200 m or 2400 m. The shallower the range the better the depth resolution and accuracy.

On/off saltwater switch for saving memory
It is possible to purchase the logger with a saltwater switch. This optional configuration and saves on the memory capacity, by only recording data when in saltwater. This on/off switch version is ideal for use on fishing gear, to stop recordings when gear is on deck and automatically start again when submerged.

SensorsConductivity (salinity), temperature, pressure (depth)
Size (Diameter x Length)15 mm x 50 mm
Housing MaterialAlumina (Ceramic)
Weight (in Air/in Water)21g/13g
Data Resolution12 bits
Conductivity RangesChoose between: 13 to 63 mS/cm, 13-50 mS/cm, 3-37 mS/cm or 0.3-5 mS/cm
Conductivity ResolutionRange 13-63 mS/cm: 0.02 mS/cm

Range 13-50 mS/cm: 0.01 mS/cm

Range 3-37 mS/cm: 0.01 mS/cm

Range 0.3-5 mS/cm: 0.002 mS/cm

Conductivity AccuracyRange 13-63 mS/cm: +/-2 mS/cm

Range 13-50 mS/cm: +/-1.5 mS/cm

Range 3-37 mS/cm: +/-1.5 mS/cm

Range 0.3-5 mS/cm: +/-0.3 mS/cm

Salinity RangeDepends on conductivity and temp. range (consult with Star-Oddi)
Salinity Resolution*Range 13-63 mS/cm: 0.01 PSU

Range 13-50 mS/cm: 0.01 PSU

Range 3-37 mS/cm: 0.01 PSU

Range 0.3-5 mS/cm: 0.0005 PSU

Salinity Accuracy*Range 13-63 mS/cm: +/-1.5 PSU

Range 13-50 mS/cm: +/-1 PSU

Range 3-37 mS/cm: +/-1 PSU

Range 0.3-5 mS/cm: +/-0.1 PSU

Saltwater SwitchAvailable upon customer request (DST CTD logic)
Temperature Range-1°C to +40°C (30°F to 104°F)
Temperature Resolution0.032°C (0.058°F)
Temperature Accuracy+/-0.1°C (0.18°F)
Temperature Response TimeTime constant (63%) reached in 20 sec.
Standard Depth Ranges1m-100m, 5m-500m, 5m-1200m, 10m-2400m
Depth Resolution0.03% of selected range
Depth Accuracy+/-0.6% of selected range
Depth Response TimeImmediate
Memory TypeNon-volatile EEPROM
Memory Capacity87,217 measurements per sensor
Memory MangementCustom programming
Sampling IntervalUser specified in second(s) minute(s), or hour(s)
Minimum Measuring Interval1 second
Multiple Intervals OptionUp to 7 different intervals
Data Retention25 years
ClockReal time clock. Accuracy +/-1 min/month.
CommunicationsCommunication Box, wirelss transmission when DST sits in the box. Connection to PC: USB cable.
Attachment Hole0.9 mm (diameter)
Battery Life4 years**
Replaceable BatteryNo

*Based on conductivity full scale accuracy at 24°C.
**For sampling interval of 10 minutes.
Warranty: 12 months.

Simple in Use, From Setup to Data Retrieval
The logger and the accompanying items are designed for ease of use throughout the research process, from setting up the logger, attaching it, to retrieving and analysing the data. The CTD logger is supported by the SeaStar software and a Communication Box which have to be purchased with the first order.

Programming the Logger
To launch the CTD probe for measuring it is placed into the Communication Box interface that connects with a USB cable to a PC computer. In the SeaStar software, the user sets the start time, start date and sampling interval before starting the logger in measurement mode. The logger synchronizes its internal clock with the date & time on the computer being used.

Single or multiple intervals
There are two modes for sampling, either at a single interval throughout the period or multiple intervals. When choosing multiple interval programming it is possible to define up to seven different intervals and a number of measurements for each interval. Shifting between wide and narrow intervals can help in extending the measuring period due to memory limitation and have more frequent measurements during certain time periods.

Memory and Battery Life Calculations
The software automatically calculates when memory fills up based on certain interval settings, making it easier for the user to decide how to program the logger. Estimation on battery consumption during that time period is also calculated.

Uploading the Data
After recovering the logger, it is inserted into the communication box and the recorded data is uploaded to the software. The results are displayed both in graphic and tabular form and the data can be exported to other programs. The time series data shows each measurement with its own time stamp.

Low energy consumption
After data retrieval the logger can be reused, as long as the batteries last. Battery life estimation is always reported upon connection with the logger. Due to the low energy consumption circuitry design the battery life is long, but actual lifetime depends on usage and sampling interval used.