• Light & portable (2.0 kg in air & 1.0 kg in water)
  • No cable required due to built-in large memory capacity
  • Wet connector (patented) prevents water leakage
  • Rechargeable Lithiium-lon battery pack
  • Calendar/time memory
  • Simple connection between the instrument & PC through
    an interface box
  • 16-bit high resoIution
  • Optional Chlorophyll / Turbidity sensor avaiIable
  • Robust titanium pressure case - no corrosion

Wet connector (patented technology)
& easily visible pilot lamp
The COMPACT-CTD is a small, light and precise data logger equipped with sensors to measure conductivity, temperature & depth. A chlorophyll / turbidity sensor is available as an option. Since the COMPACT-CTD is so light and because no communication cable is required, it is very easy to take profiling measurements just by lowering the COMPACT-CTD with a rope.
Along with profiling capabilities in depth trigger and time trigger modes, the COMPACT-CTD can be used for short-term mooring observations.
The COMPACT-CTD has a built-in 2M-byte flash memory that enables multiple casts without the need to transfer data between casts.
For example, the COMPACT-CTD can take 190 profiles to 100 m depth with 10 cm depth pitch without the need for data transfer. With the built-in rechargeable lithium-ion battery, the COMPACT-CTD is capable of 10 hours of continuous measurements (time trigger mode with 0.2 second measuring intervals). The non-volatile flash-memory prevents data loss in case of power failure or irregular battery voltage.
The COMPACT-CTD has been designed to avoid complicated operation and maintenance issues that can cause data acquisition problems. A wet connector (patented technology) is used for data transfer and battery charging. Since there are no penetrating parts, there are no leakage problems. The pressure case does not have to be opened to access the data transfer connector or for charging the battery.
The data processing program offers clear and logical screens for easy operation.

Sensor Specifications
Parameters Type Measuring Range Resolution Accuracy Time Constant
Depth Semiconductor
Pressure Sensor
0 to 600m 0.01 m 0.3%FS 0.1 sec
Temperature Thermistor -5 to 40 XC 0.001 XC 0.02 XC 0.1 sec
UNESCO Formula
(Inductive Cell)
0 to 40
0 to 60 mS/cm
0.001 mS/cm
0.02 mS/cm
0.1 sec
Turbidity (Option) Ultra red light
0 to 1000 FTU
0.03 FTU 2% of measured data
or Zero-drift 0.3 FTU
0.2 sec
Chlorophyll (Option) Fluorescent 0 to 400 µg/l (Uranine) 0.01 µg/l 1 % of lineality (0 to 200 µg/l)
or Zero-drift 0.1 µg/l
0.2 sec

Specification of logger
Deployment mode Depth trigger mode Time trigger mode
Interval 0.1, 0.2, 0.5 ,1.0 m 0.1, 0.2, 0.5,1.0 second
Memory Type 2M-byte flash memory
Recording capacity at 0.1 m pitch,
190 measurements
for 100 m profile
about 200,000 data
Power rechargeable lithium-ion battery
(to be changed once a year)
measurable 10 consecutive hours
Weight 2.0 kg in air,1.0 kg in water
Dimension dia 60mm , length 462 mm
sensor guard diameter 136mm
Material Titanium
Others Calendar memory function
Interface Specification
Transfer Time About 12 min (Full data)
Charging Time Within 3 hours approx.
Weight 1.1 kg approx.
Dimension 170 x 169 x 66 mm approx.
Material Die-cast Aluminum
Power Alkaline battery (4pcs.) UM-3
(Approx. 40 hours for communication use),
AC100 - 240V (Comm / Charge use)
RS232-C Cable 5 m standard (Max. 20 m)

Sensor Picture