CTD Profiler Model SD208


  • Wireless Communication with extremely low power consumption
  • Compact & robust design
  • Auto-range for Turbidity & Fluorescence
  • Long term stability sensors
  • High memory capacity
  • Sonar equipment compatibility
  • Year-long battery capacity
  • Depth to: 6000 meters
  • Windows based software
  • Output in physical units (Calibrated Data)
  • Online plotting

CTD Profiler



Wireless remote WR104

Wireless PC dongle (range 50m)

The model SD208 is often also called CTD profiler, STD profiler, Sound Velocity profiler, CTD Instrument and CTD sonde .
The model SD208 measures, calculates and records sea water conductivity, salinity, temperature, depth (pressure), sound velocity and water density. Therefore is often the SD208 called sound profiler. Three optional sensors can be added, f. example: dissolved oxygen, fluorescence and turbidity. For optional sensors with several sensitivity ranges, the SD208 has auto range capability to automatically obtain the best sensitivity. The programmed settings and calibration coefficients are maintained in nonvolatile eeprom, and will not be changed/lost if power is disconnected. Data is recorded in physical units and simultaneously transmitted via an RS232 I/O watertight connector for on-line use or wireless serial communication by built in radio. The built in radio is a radio transmitter and receiver that operate on the band with 868Mhz. The operation length is 50 meters free air. To use: A USB radio dongle connected to a Windows computer is needed together with the software SD200W.
Main difference between SD204 and SD208 is better accuracy on the conductivity sensor. This will than also result in better salinity and sound velocity.

The accompanying software, SD200W, contains versatile functions for programming, post- and online data processing and presentations: multigraph, online plotting, density and real depth calculations (weighed profile). The program is continuously extended according to customer requests. Robustness and complete protection from leakage is obtained by vacuum molding the electronic and all other components in solid polyurethane. On/Off-switching is by a magnetic key or from keyboard by cable or wireless communication. A sealed battery compartment contains two replaceable 3.6V C-cells. In practical operation the battery capacity is sufficient for continuous year-around operation with good margin. The instrument is equipped with a mooring bar with a shackle at each end. For use in fixed position or in APB5 (Automatic Profiling Buoy), the manufacturer offers worldwide remote read-out on Internet via GPRS/Satellite (IMARSAT) by Communication Unit CU801.


Conductivity: Inductive cell, Temp & Press. Comp.
Range: 0 to 80 mS/cm
Resolution: 0.00008 mS/cm
Accuracy: +/- 0.003 mS/cm

Salinity: Calculated from C,T & D
Range: 0 to 50 ppt
Resolution: 0.00008 ppt
Accuracy: +/- 0.003 ppt

Range: -2 to +40°C
Resolution: 0.0002°C
Accuracy: +/- 0.002°C
Response time: 0.1 sec

Pressure: Specify desired depth range with order
Ranges: 500, 1000, 2000, -- 6000 m
Resolution: 0.01 dbar (m)
Accuracy:  +/- 0.01% FS
Response time: 0.1 sec

Sound Velocity: Calculated from S,T & D
Range: 1300 to 1700 m/s
Resolution: 0,5 cm/s
Accuracy: +/-2 cm/s

Dissolved oxygen: (optional)
Sensor type: SAIV205 (electro-chemical) and RINKO III (optical)
Range: 0 to 20 mg/l 0 to 20 mg/l
Resolution: 0.01 mg/l 0,08 mg/l
Accuracy: +/- 0.2 mg/l +/- 0,5 mg/l

Fluorescence: (optional)
Sensor type: Fluorescein/Chlorophyll/Rhodamine/CDOM
Ranges: 2.5, 7.5, 25, 75 ug/l selectable/autorange
Resolution: 0.03 µg/l

Turbidity: (optional)
Sensor type: Backscatter
Ranges: 12.5, 62.5, 250, 750 FTU
selectable /autorange
Linearity: < 2%

Real time clock: +/- 2 sec/day

Modes: STD/CTD with/without sound velocity, oxygen and optional sensor.

Intervals: 1 sec to 180 min.

Capacity: 56000 data sets of STD/CTD

Data output:
Cable: RS232 ASCII code.1200-38400 baud, 1 start, 7 data, 1 stop, even parity or
1 start, 8 data, 1 stop, no parity selectable via menu

Wireless: 868 Mhz RS232 code 9600 baud, 1 start, 8 data, 1 stop, no parity
Range: 50m

Power: 2 ea. 3.6V lithium C-cells.
Recommended type: SAFT LSH14/LS26500 (Sufficient for 1.500.000 data sets)
External: 10-30VDC

Material: Vacuum molded polyurethane and titanium
Dimension: Length 400 mm. Diameter 60 mm
Weight: In air: 2 kg.  In water: 0.8 kg.

Packing: Suitcase (534x427x157 mm), Grossweight 5,5 kg

Accessories: (included) On/Off magnetic key, PC communication cable 2,5m, MINISOFT
SD200W program and Operating Manual
(optional): Wireless Receiver with USB Connector (optional)

Warranty: Two years against faulty materials and workmanship

Download datasheet as PDF