Ocean Seven 320 Plus WOCE-CTD


The OCEAN SEVEN 320Plus WOCE-CTD multiparameter probe is the result of Idronaut’s 35-year-old experience in the design and manufacturing of high-quality fast response CTDs. The OCEAN SEVEN 320Plus CTD well meets the WOCE programme accuracy, precision and resolution specifications.
The CTD can be easily equipped with an additional redundant conductivity and temperature (CT) sensor pair without the need for underwater connectors. The CT redundant sensors permit the gathering of extremely precise data with a verifiable data quality.
The OCEAN SEVEN 320Plus WOCE-CTD is equipped with the well-known IDRONAUT full ocean depth, pump-free and long-term stability sensors.
Central to which, is the high accuracy seven-platinum-ring quartz conductivity cell (patented), which can be cleaned in the field without the need for re-calibration. This unique quartz cell employs a large diameter (8 mm) and a short length (46 mm) to guarantee self-flushing and no clogging after long-term deployment even in biologically active waters. Competitors’ sensors, which present few mm only of cell orifice and very long cell length, are prone to clog even if protected by dangerous and poisonous antifouling devices.
The OCEAN SEVEN 320Plus WOCE-CTD multiparameter probe does not require pumps or any other external device to flush the sensors, which minimizes its power consumption and allows the use in Arctica and Antarctica. However, pump is optional.
Data telemetry available for on-line full ocean depth real-time data transmission. Other interfaces like RS422 and wireless Bluetooth® can be optionally installed.
The OCEAN SEVEN 320Plus WOCE-CTD, because of an innovative 24-bit high-speed CT digitizer circuit, provides 40 Hz sampling rate. Furthermore, the highly precise pressure transducer enhances the pressure sensor accuracy/precision to 0.01 % Full Scale (FS).
The OCEAN SEVEN 320Plus WOCE-CTD multiparameter probe can accommodate up to sixteen 16-bit sensor analogue inputs, which can be added at any time, making this Idronaut probe an investment for the future.

    The high-precision 0.01%FS pressure transducer is based on a piezoresisitive bridge, floating on oil, with drift-free sensor interface. Temperature dependency and non-linearity are mathematically compensated by the interfacing electronics. Standard pressure transducers immediately available: 100, 1000, 2000, 4000, 6000, 10000 dbar.
    Features a very fast platinum resistance thermometer (time constant: 50 ms). Negligible self-heating effect.
    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.
    More reliable operation at sea minimizing risk of data loss. The redundancy principle allows better control of any possible sensor drift during long field campaigns.
  • OXYGEN SENSOR (7000 m operation):
    Features a pressure-compensated polarographic sensor with a replaceable cap or/and advanced optical dissolved oxygen sensor. Both sensor can be installed at the same time.
    High-pressure low impedance glass membrane pH electrode in conjunction with a unique KCl or NaCl gel double junction reference electrode and a differential pH preamplifier, 1013 ÷ 1014 ohm input impedance.
    Via RS232C interface. Optional interfaces are: long distance (10000 m) telemetry, RS422 and Wireless Bluetooth.
    Allows storage of up to 16M dataset, for each of the 7 standard acquired parameters together with date & time, using the 4 GByte non volatile memory.
    The following sensors, probes are currently interfaced:
    » GENERAL OCEANICS – Rosette Water Samplers 1018 and 1015.
    » IDRONAUT – High Precision 0.01 % Pressure Transducer.
    » IDRONAUT – String and Weight Bottom Sensor.
    » IDRONAUT – Optical dissolved oxygen sensor.
    » IDRONAUT – MISS Sampling system.
    » PSA916D Sonar Altimeter, 6000 m.
    » LI-COR – LI-192SA and LI-193SA Underwater Quantum sensors.
    » CHELSEA – MINItracka, Unilux and Trilux Fluorometers.
    » WET Labs – C-Star Transmissometer and ECO Fluorometers.
    » SEAPOINT – Fluorometers and Turbidity Meter.
    » TURNER DESIGNS – Cyclops, CFluor Fluorometers.
    » D & A INSTRUMENT COMPANY – OBS-3 Sensor.
    » VALEPORT – MiniSVS Sound Velocity Sensors.

The internal and the optional external submersible battery packs permit continuous probe operation for about 7 and 70 hours respectively. Rechargeable or lithium batteries can also be used. Twelve batteries: 1.2 V, 2.85 Ah, NiMH cells are installed in the internal battery pack.
The OCEAN SEVEN 320Plus CTD can measure, store and transmit sensor data by these modes of operation:

  • Pressure:
    Data is sampled at regular pressure intervals. Multiple profiles can be obtained by switching the CTD ON and OFF.
  • Timed:
    OS320Plus collects a series of samples and then sleeps for the configured time interval before waking up again and repeating the acquisitions. Time interval can be configured from 0.1s up to 1 day. Battery power is conserved while the probe is in sleep mode.
  • Conditioned:
    Data is sampled at configurable data rates starting when the selected parameter overcomes the configured boundary. Sampling continues until the selected parameter falls below the configured boundary. Whenever the acquisition cycle starts, a configurable sampling rate 0.1..20 Hz is used. Monitoring of the selected parameter occurs at the configurable interval between 0.1s up to 1 day.
  • Continuous:
    Data is sampled at configurable sampling rates starting when the operator switches on the probe. Sampling continues until the probe is switched off. Multiple cycles can be obtained by switching the CTD ON and OFF.
  • Real-time:
    Data is sent to the control system at sampling rates of: 20, 30 and 40 Hz using REDAS-5 software.

The unattended acquisition can be activated by means of a magnetic switch present on the probe top cover. Extension of the internal battery life is automatically obtained through a power management procedure that switches the probe OFF between data acquisitions. The probe is equipped with an internal non-volatile memory which can store up to a 16M dataset, each data set being composed of date, time and measurement of the standard sensors. Stored data is uploaded at the end of the measuring cycles.
The OCEAN SEVEN 320Plus CTD can be configured to be directly interfaced to a personal computer by means of the RS232C serial port or by telemetry. The telemetry and RS422 interfaces remedy the limitations of the RS232C serial interface (cable length and number of conductors). When using the telemetry interface, the Telemetry Deck Unit is required to convert serial, RS232C type signals from a PC communication port, into telemetry signals (and vice versa) which must flow superimposed on the probe power supply along the armoured single conductor coaxial cable.
Probe communication is achieved through one of the two male connectors installed on the top end cap of the probe. A six-pole connector is used for the RS232C and RS422 interfaces and for the power input, while, a two-pole connector is used for the telemetry interface.

REDAS-5 software, through a simplified and friendly operator interface, allows taking full control of the OCEAN SEVEN 320Plus CTD and facilitates real-time data acquisitions, configuration of unattended acquisition cycles and uploading of data stored in the probe memory. REDAS-5 programme is a true 32-bit Windows application, which flawlessly runs on Windows. REDAS-5 shows the acquired data graphically and numerically thus allowing the operator to dynamically change the graphical and numerical set-up during data acquisition. Post-processing functions and data extraction procedures, in function of time, pressure or numerical intervals can be applied to acquire data in real time or on data retrieved from the probe memory. Among the operations that REDAS-5 can perform, it is worth mentioning: automatic start and stop of data acquisition; management of the bottle sampling (Rosette); processing and filtering of acquired data in real time (time lag compensation, smoothing etc.); acquisition of geographical coordinates from a GPS device; acquired data conversion into text files; automatic scaling of the graphical window X and Y axis. REDAS-5 software allows 20, 30 and 40 Hz sampling rate.

OCEAN SEVEN 320Plus Telemetry System Performance Chart

(*) The above performance is obtained using the 6.4 mm diameter (1/4 inch) Rochester cable 1-H-255 which has an electrical resistance of 23 Ω/Km and capacity of 138 pF/m.
The Ocean Seven 320Plus CTD operates with the standard Rochester coaxial armoured cables (1/10, 1/8, 1/4, 1/2 inch) present in oceanographic vessels having a total resistance up to 250 ohms.

All the sensors installed in the OCEAN SEVEN 320Plus CTD (see table for SENSOR SPECIFICATIONS) are manufactured by IDRONAUT and are exported all over the world. They are used by several other multiparameter probe manufacturers. All sensors have extremely low time constants: 50 milliseconds for physical parameters (CTD) at 1 m/s profiling speed and 3 seconds for chemical parameters. CTD sensor high resolution and accuracy are obtained because of the advanced sensor conditioning circuits and the 24-bit Sigma Delta A/D Converters.
The OS320Plus multiparameter CTD can be equipped with the following sensors to measure:

(1) Other standard pressure transducers, immediately available, have: 100, 1000, 2000, 4000 and 6000 dbar ranges.
(2) At 1 m/second flow rate.
(3) Optional.
(4) From nitrogen to air.
(5) A special FAST membrane, with time constant 3s, is available upon request.
(6) Through the auxiliary inputs, optional sensors like: Fluorometer, Turbidity Meter, Transmissometer, Altimeter, Par, can be interfaced. Ten auxiliary analogue inputs are available inside the probe.
The fundamental properties of seawater like: Salinity, Sound Speed, Water Density, Oxygen ppm are obtained using the algorithms described in the UNESCO “Technical papers in marine science no.44 – Algorithms for computation of fundamental properties of sea water”.
The fresh water properties like: TDS (Total Dissolved Solids), Fresh Water Conductivity corrected at 20°C and 25°C are automatically calculated.

    The new MKPlus Deck Unit powers and interfaces the OCEAN SEVEN 3xx CTDs with an auto-adaptive V32/V32bis modem to optimize the full-duplex communication in real time, depending on the connection conditions. The communication speed of 14.400 bps over the oceanographic cable allows obtaining a higher transfer rate from the interfaced OCEAN SEVEN 3xx CTDs. Visual feedback is provided to the operator during communication to indicate the line quality and speed automatically selected by the MKPlus modem.
    The MKPlus innovative V32/V32bis telemetry modem has been added to the basic electronics and functions of the well-proven MK Deck Unit. Up to 100 units were sold all over the world. The MKPlus Deck Unit provides high voltage telemetry power supply (220 VDC) to allow the OCEAN SEVEN 3xx CTDs to interface and power several additional probes. The MKPlus Deck Unit is housed in a 19″ rack-mountable metallic box and is designed for on-board operations. The MKPlus Deck Unit operates with: 115/220 VAC +/-10%, 50-60 Hz +/- 5%. Telemetry power supply: 220 VDC (max 1A@12V).
    Dimensions: 480x160x90. Weight: 3 Kg.
    Portable lightweight and extremely rugged reader based on the Windows Mobile™ software, which overcomes the limitations that the use of a PC in the field and in hostile environments normally implies, like: battery endurance, display reading under sunlight, water and dust tightness, weight, etc. The Portable Reader interfaces the probe through a built-in RS232-C interface and a dedicated programme.
    Includes 2-way or 5-way slip ring and it can hold up to 350 m of 5 mm polyurethane jacketed armoured cable or 100 m of 8.3 mm polyurethane multi-conductor shielded cable.
    A strain relieved 5 mm polyurethane jacketed armoured cable type Idronaut – breaking strength: 200 kg – weight per km: 40 kg.
  • RS232C/RS422 CABLE – Ø 8.3 mm – POLYURETHANE:
    Multi-conductor shielded cable – Kevlar amoured – type Idronaut Ø 8.3 mm – specifically designed for RS422 or RS232C interface. Composed of 2 pairs: one 2×24 AWG twisted together and one 2×19 AWG – breaking strength: >250 kg. RS232C data transmission limits this cable length to 200 metres. RS422 data transmission enables this cable length to 1000 metres. Weight: 3,6 kg/100 m in water; 9.6 kg/100 m in air.
    For sensor and/or upper connector protection: Ø 260 mm. Mooring frame to house the CTD and two additional probes: on custom request.
    The following battery packs, 14.4VDC (no. 12 NiMH cells), 4.5 Ah are available:
    – Ø 75 x 315 mm, 1500 m max depth operation.
    The external battery pack is held by the probe by means of one or two POM flanges.
    Easily connectable to a pumped source of seawater (water volume 200÷300 ml), this option converts the Ocean Seven 320Plus CTD from a profiling CTD into a very accurate FerryBox thermosalinograph.
    More reliable operation at sea minimizing the risk of data loss. The redundancy principle allows better control of any possible sensor drift during long filed campaigns.
    The IDRONAUT Wireless Adapter allows full duplex communications between the OCEAN SEVEN 320Plus probe and a personal computer or PDA devices equipped with a Bluetooth® device. The Wireless Adapter provides an interface conforming to the Bluetooth® class 1 (100 m) connectivity SPP protocol.
    Instead of the RS232C interface, allows real-time communication with the probe using cables long up to 1000 m.
    General Oceanics Rosettes mod. 1018 and 1015 (Tone or Voltage Firing) are interfaced to perform attended and unattended bottle firing in function of time and/or depth variations. The latter is obtained through user’s configurable depth profiles or depth steps. Furthermore, bottle firing can be accomplished in real time whenever the probe operates with the telemetry system.