Valeport MIDAS - Monitor CTD Profiler

The MONITOR CTD has been developed from Valeport’s MIDAS CTD, utilising the same accurate, robust sensors and synchronised sampling technique, but packaged as a smaller, lightweight unit to suit small boat or shallow water applications.

Sensors
The MONITOR CTD is fitted with Valeport’s high stability conductivity sensor, a high accuracy temperature compensated piezo-resistive pressure transducer, and a fast response PRT temperature sensor.

Conductivity

• Range: 0 - 80 mS/cm
• Resolution: 0.002mS/cm
• Accuracy: ±0.01mS/cm

Temperature

• Range: -5°C to +35°C
• Resolution: 0.005°C
• Accuracy: ±0.01°C

Pressure

• Range: 50 Bar standard, others available
• Resolution: 0.005% range
• Accuracy: ±0.1% range

Data Acquisition
The MONITOR CTD uses the concept of distributed processing, where each sensor has its own microprocessor controlling sampling and calibration of readings. Each of these is then controlled by a central processor, which issues global commands and handles all the data. This means that all data is sampled at precisely the same instant, giving superior quality profile data.

Sampling Modes

• Continuous: Regular output from all sensors at 1, 2, 4 or 8Hz.
• Burst: Regular sampling pattern, where instrument takes a number of readings, then sleeps for a defined time.
• Trip/Profile: Data is output as a chosen parameter changes by a set value, usually Pressure for profiling.
• Conditional: Instrument sleeps until a selected parameter reaches a set value.
• Delay: Instrument sleeps until predefined start time

Communications
The instrument will operate autonomously, with setup and data extraction performed by direct communications with PC before and after deployment. It also operates in real time, with a choice of communication protocols for a variety of cable lengths, all fitted as standard and selected by pin choice on the output connector:

Standard

• RS232 Up to 200m cable, direct to serial port via USB adaptor
• RS485 Up to 1000m cable, addressable half duplex comms
• Baud Rate: 2400 - 115200 (FSK fixed at 19200, USB 460800)
• Protocol: 8 data bits, 1 stop bit, No parity, No flow control

Memory
The MONITOR CTD is fitted with 16Mb solid state non-volatile FLASH memory. Total capacity depends on sampling mode; continuous & burst modes have a single time stamp at the start of the file, trip mode (profiling) stores a time stamp with each reading. A single line of CTD data uses 6 bytes, and a time stamp uses 7 bytes.

• Continuous: >2,750,000 data points
• Profile: >1,200,000 data points (>600 profiles to 500m).

Electrical

• Internal: 8 x C cells, 1.5v alkaline or 3.6v lithium
• External: 9 - 30vDC
• Power: 0.6W (sampling), <1mW (sleeping)
• Battery Life:
• <100 hours operation (alkaline)
• <250 hours operation (lithium)
• Connector: Subconn MCBH10F

Physical

• Materials: Acetal housing, polyurethane and titanium sensor components, stainless steel (316) cage
• Depth Rating: 500m
• Instrument Size: 88mmØ x 540mm long
• Cage Size: 640 x 140 x 120mm
• Weight (in cage): 7.5kg (in air), 4.5kg (in water)
• Shipping: 74 x 35 x 27cm, 17kg

Software
System is supplied with DataLog Express Windows based PC software, for instrument setup, data extraction and display. DataLog Express is license free.