The CTD48M is a high quality, high accuracy 4 channel memory 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: 001 Category:


Multiparameter probe CTD 48M

The CTD48M probe is a very small and handy microprocessor controlled multiparameter memory probe for for limnologic and oceanographic measurement with up to 4 sensors and for depth up to 6000 m. It measures conductivity, temperature, pressure and one optional parameter.

Data are stored in a standard flash memory card with a capacity limited to 128 Mbytes by the internal firmware. Up to 3 000 000 CTD data sets can be recorded on this memory.

The CTD48M allows operation in different modes:

  • Continuous mode: each data set is stored.
  • Time mode: data sets are only stored at programmable intervals with several selectable schemes.
  • Increment mode: data sets are stored at programmable depth increments, up to 255 files can be stored without the need for data retrieval in between
  • Online mode (RS-232 – on multiconductor cables)

The CTD48M is equipped with a 4 channel data acquisition system with 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 probe power supply is activated by touching a reed contact with a magnetic rod. LED displays power supply status and optical control of memory access.
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 and memory 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 (titanium)
  • 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

Memory, Online

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


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. It is also used to configure and readout the data memory.

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 and storage of data for all probes in online- or memory mode.

  • 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 MCBH5M 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
  • CTD48M
  • Probe user manual
  • Software manual SST-SDA
  • Calibration documents
  • Software
  • Batteries
  • Hexagon key with t-shaped plastic handle
  • Shackle
  • Dummy cap with locking sleeve
  • Configuration cable (5m)
  • USB cable
  • RS-232 to USB converter
  • Magnetic rod
  • O-rings
  • Titanium screws
  • Silicon grease
  • 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