CTD 48

CTD 48

The CTD48 is a high quality, high accuracy 4 channel online probe for oceanographic and limnological measurement of conductivity, temperature, depth and one optional parameter for depth up to 6000 m.

Standard models:
Online probe for measurement of conductivity, pressure, temperature + 1 optional sensor

Standard sensors:

  • Conductivity (С)
  • Temperature (T)
  • Pressure (D)

Additional sensors:

  • Dissolved Oxygen
  • Turbidity
  • pH
  • Redox (OPR)

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SKU: 3010000 Category:


Multiparameter probe CTD 48

The CTD48 is a very small and handy microprocessor controlled multiparameter probe for precise online measurements of pressure, temperature, conductivity and one optional parameter.

The probe is especially designed for limnological measurements on lakes, rivers and estuaries but can be used also in shallow water and in the oceanographic range up to 6000 m depth.

The CTD48 is equipped with a 4 channel data acquisition system with internal 20 bit resolution. Data output is 16 bit. A high long-term stability and automatic self-calibration of the analogue digital converter guarantees stable and precise CTD measurements for many years.

The CTD48 is equipped with several interfaces:

  • RS-232
  • RS-485
  • FSK.

The RS-232 port can be used with multi-conductor cable up to distances of several hundred meters. The user can operate the probe easily from small boats and ships. The serial data will be applied directly to the serial port of a PC. Power has to be provided externally e.g. by a 12V battery or a regulated power supply.

RS-485 is used for data transfer in areas with high environmental electromagnetic noise, a safe data transmission requires cable with twisted pairs. RS-485 interface can drive up to 1000 m cable length on nearly any cable. The RS-485 signals need to be converted into RS-232 before being acquired by a PC.

FSK transmission is used mainly on single-conductor cables. Data is modulated on the power supply rail for a long distance data transmission. FSK operation requires a special power supply interface with a demodulator unit that converts the FSK data into RS-232 or USB 2.0 format.

The supplied Standard Data Acquisition Software package “SST-SDA” includes the handling of the logging process and the display of online or recorded data with a shared graphic user interface. The “SST-SDA” is a part of our shipment.

Standard models:
Online probe for measurement of conductivity, pressure, temperature + 1 optional sensor

Standard sensors:

  • Conductivity (С)
  • Temperature (T)
  • Pressure (D)

Additional sensors:

  • Dissolved Oxygen
  • Turbidity
  • pH
  • Redox (OPR)

Calculated parameters:

  • salinity
  • sound velocity
  • Kappa 25 mS/cm
  • sigma

Main Features:

  • low weight
  • easy handling
  • up to 4 sensors on the bottom cap
  • non-corrosive titanium housing
  • depth range up to 6000 m
  • SDA data acquisition software running under various versions of Microsoft Windows (a part of the shipment)
  • calculations according to UNESCO formulae
ten year warranty

Additional information

Max. Depth

up to 50 m, up to 100 m, up to 200 m, up to 500 m, up to 1000 m, up to 2000 m, up to 4000 m, up to 6000 m

Field of Application

Brackwater, Drinking water, Ground water, Fresh water, Salt water, Offshore

Measuring mode


Special functions

borehole probe


0 – 10 ms/cm, 0 – 70 ms/cm, 0 – 300 ms/cm

Temperature PT100

From -2 – 36°C, From -2 – 60 °C


H2S resistant, Standard


H2S resistant, standard




0 – 25 ftu/ntu, 0 – 125 ftu/ntu, 0 – 500 ftu/ntu, 0 – 4000 ftu/ntu

Special sensors

Current meter, H2S

The data transfer and the power supply of the probes over longer cables (up to 6000 m) is carried out when using multi-conductor cables (at least 4-wire) via a serial interface (RS-485) or when using a “single-conductor cable” (steel cable with internal conductor) via the FSK- Interface (Freqency Shift Keying).

For shorter cable lengths (up to 500 m) the RS-232 interface can be used.

If the probe is equipped with a USB interface, it is recommended to read the stored data via this interface, since a shorter read-out time can be achieved. The cable length of the USB interface should not be longer than 5 m.

Special probes (for example for installation in an underwater vehicle) can be equipped with a fast Ethernet interface (LAN).

The probes are provided with a program (SDA) for the configuration, readout of stored data, numerical and graphical representation of the data.

Power: 9…30 VDC
Power consumption: approx. 0,5 W (sensor-dependent)
Serial port: RS-232 or RS-485 (optional FSK)
Data transmission : 5 CTD sets/s
Connector: SUBCONN MCBH4M Ti


  • Housing: titanium, grade 2 (up to 2000 m); titanium, grade 5 (up to 6000 m)
  • Connector: titanium, neoprene

Dimensions and Weights

  • Length (housing):
    240 mm (probes up to 2000 m)
    260 mm (probes up to 6000 m)
  • Length (protection frame): 130 mm
  • Length (overall with connector):
    approx. 450 mm (probes up to 2000 m)
    approx. 470 mm (probes up to 6000 m)
  • Diameter (housing): 48 mm
  • Weight (in air): approx. 1.2 kg
  • Robust plastic case
  • CTD48
  • Probe user manual
  • Software manual SST-SDA
  • Calibration documents
  • Software
  • Shackle
  • Dummy cap with locking sleeve
  • Configuration cable (5m)
  • RS-232 to USB converter
  • Quick start guide

We offer calibration of several probes and sensors

  • Pressure (dead weight tester)
  • Temperature: Millikelvin Thermometer Pt 100 (ITS 90, IEC 751)
  • Conductivity: Salinometer, Guildline Autosal 8400B / Portasal 8410A (standard sea water)
  • pH / Redox (buffer solutions)
  • Oxygen