Ocean Seven 308 CTD Logger
VERY LOW POWER, SELF-RECORDING, UV-ANTIFOULING, ARCTIC, ANTARCTICA, BRINE, MOORINGs, ROVs, AUVs
The OCEAN SEVEN 308 CTD combines very high-quality electronics with exceptional sensors accuracy fulfilling the demand for a self-recording high performance CTD probe with very compact dimension and very low power consumption. This CTD can be easily integrated/adapted to third-party systems such us floating profilers and/or oceanographic moorings, ROVs and AUVs. IDRONAUT prides itself on the design of its full ocean depth, pump-free, low-maintenance sensor, central to which is the high accuracy seven-platinum-ring quartz conductivity cell. The self-flushing sensors makes this CTD ideal for fast profiling in a wide range of water types. The OS308 CTD standard interface is RS232C; other optional interfaces are: RS485 and wireless. The OS308 housing can be manufactured with either a 316 grade L stainless steel or titanium allowing deployment to depths of 1000 or 7000/10.000 dbar respectively.
FEATURES AND OPTIONS AVAILABLE
Features a very fast platinum resistance thermometer (response time: 50 ms). Negligible self-heating effect. Optionally combined C/T sensor featuring a 7ms fast thermistor (20 ms after processing) integrated in the conductivity cell is available upon request.
The high accuracy seven-platinum-ring quartz conductivity cell (patented) can be cleaned in the field without the need for re-calibration. This unique quartz cell employs a large diameter (8mm) and a short length (46mm) to guarantee self-flushing and no clogging after long-term deployment even in biologically active waters. Furthermore, an optional UV LED (280 nm), integrated into the conductivity cell, sterilizes the sample under measurement, thus avoiding the early growth of biofouling inside the quartz measuring cell.
Automatic, real-time data transmission compatible with: Bluefin and OEX AUVs are available, together with a proprietary data transmission format. To further reduce weight and size a shorter housing is available upon request.
| Continuous: | Sampling at configurable rate: 0.1 Hz to 22 Hz. Multiple acquisition cycles can be obtained by switching the CTD on/off. |
| Pressure: | Data is sampled at pressure intervals. Multiple profiles are obtained by switching the CTD on/off. |
| Timed: | CTD collects a series of samples and then sleeps for the configured time interval. Time intervals are between 20s up to1 day. |
| Conditional: | Data acquisition is started and continues while the reading from a selected sensor is above a threshold value at configurable sampling rate 0.1 Hz up to 22 Hz. Monitoring of the selected sensor threshold value can be configured to occur at intervals between 20s up to 1 day. |
| Burst: | Burst sampling carried out at configured time intervals: between 20s up to 1 day. |
The OS308 can be equipped with an internal lithium battery rechargeable, without opening the probe, preserving its mechanical integrity and ensuring maximum operational safety.
The integrated battery gauge continuously monitors the lithium battery temperature, providing real-time protection and optimized re-charging performances. Ongoing consumption analysis delivers accurate and reliable runtime estimation, enabling safer, more predictable, and fully controlled unattended operation cycles.
The OS308 CTD can be equipped with the following sensors to measure:
| Parameter | Extension | Range | Initial Accuracy | Resolution | Response Time |
|---|---|---|---|---|---|
| Pressure | 0..1000 dbar (1) | ±0.05% FS | 0.002% FS | 50 ms | |
| Temperature | -3..+50 °C | ±0.0015 °C | 0.0001 °C | 50 ms | |
| Conductivity | Salt water | 0..70 mS/cm (4) | ±0.003 mS/cm | 0.0001 mS/cm | 50 ms (2) |
| Fresh water | 0...7000 µS/cm | ±5 µS/cm | 0.1 µS/cm | 50 ms (2) | |
| Brine | 0..350 mS/cm (3) | ±0.01 mS/cm | 0.0001 mS/cm | 50 ms (2) |
(1) Other standard pressure transducers, immediately available, have: 10, 40, 100, 200, 500, 2000, 4000, 7000 dbar ranges.
(2) At 1 m/second flow rate.
(3) A special calibration is needed.
(4) Extended ranges available upon request.
The fundamental properties of seawater like: Salinity, Water Density, Oxygen ppm are obtained using the algorithms described in the UNESCO “Technical papers in marine science no.44”.
The fresh water properties like: TDS (Total Dissolved Solids), Fresh Water Conductivity corrected at 20°C and 25°C are automatically calculated.
| Real-time and logging: | Up to 22 Hz. |
| Interfaces: | Wired: RS232C, RS485. Wireless: WiFi, Bluetooth. |
| Communication speed: | 115k2 bps, up to 921k6 bps. |
| Data memory: | 4 GBytes. |
| Power Supply - Battery: | 3.1..5.5 VDC. Running: 70 mA @ 3.6VDC. Standby: 4 μA @ 3.6VDC. |
| Power supply - External power: | 9..30 VDC. |
| Housing | 1000 dbar Body:AISI316L End Caps:POM (1) | 1000 dbar Body:TITANIUM End Caps:POM | 7000 dbar Titanium |
|---|---|---|---|
| Weight in air | 1.1 Kg | 1.5 Kg | 1.8 Kg |
| Diameter | 43 mm (Upper cap: 48 mm) | 48 mm | 48 mm |
| Weight in water | 0.65 Kg | 0.9 Kg | 1.1 Kg |
| Length | 535 mm | 540 mm | 535 mm |
(1) AUV version shorter housing is available upon request.
Idronaut software allow the operator to configure the OS308 data acquisition, logger functions and upload data from the memory. They are:
- WTERM: Windows Terminal emulation software to easily communicate with the OS308 using the built-in operator interface and communication protocol. Users are easily able to view real time data, configure the probe for unattended acquisition and upload stored data.
- REDAS-5: Windows Data processing and retrieval software, which allows the display and plotting of conductivity, temperature, pressure and derived variables such as salinity, sound speed and water density, according to UNESCO formulas and recommendations.
