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MIDAS DWR – Directional Wave Recorder

The most cost-effective solution to directional wave monitoring requirements in all shallow water coastal applications, The MIDAS DWR Directional Wave Recorder represents a significant advance in PUV wave recording technology.

The MIDAS DWR brings a range of unique features, as well as the standard non-directional data available from the MIDAS WTR, the MIDAS DWR performs full onboard directional data analysis, allowing real-time directional information at an unsurpassed 2° resolution.


Support

MIDAS DWR Datasheet
Midas DWR Operating Manual

Software

WaveLog Express
F7

Technical Specifications

Sensors

The MIDAS DWR is fitted with a choice of strain gauge or high accuracy piezo-resistive pressure sensors, and a fast response PRT temperature sensor as standard. Note that whilst the piezo-resistive sensor offers a higher absolute accuracy, the quality of wave data owes more to deployment location and sampling pattern than to sensor performance. Optional additional sensors include Conductivity and Turbidity.

Pressure (high accuracy)

Type
Piezo-Resistive
Range
100dbar (90m water)
Accuracy
+/-0.01%
Resolution
0.001%

Pressure (standard)

Type
Strain Gauge
Range
50 dbar (40m water)
Accuracy
+/-0.04%
Resolution
0.001%

Temperature

Type
PRT
Range
-5 - +35°C
Accuracy
+/-0.01°C
Resolution
0.005°C

Compass

Type
Fluxgate
Range
0 – 360°
Accuracy
+/-1°
Resolution
0.1°

Current

Type
2 Axis EM
Range
+/-5m/s
Accuracy
+/-1%
Resolution
0.001m/s

Conductivity (optional)

Type
Inductive Coils
Range
0 – 80 mS/cm
Accuracy
+/-0.01 mS/cm
Resolution
0.004 mS/cm

Turbidity (optional)

Type
Seapoint STM
Range
0 – 2000 FTU
Accuracy
+/-2%
Resolution
0.005% Scale

Data Acquisition

In order to correctly measure wave activity, Linear Wave Theory requires a specific number of data points to be sampled over a period of time. These data points are then processed on board the instrument to generate an accurate summary of the wave activity during the measured period. The MIDAS DWR therefore operates in a strict pattern of “sample, process, sleep”, with the user controlling the number of samples and the sampling rate, together with the duration of the sleep period. This may be minimised for almost continuous sampling, but obviously at the expense of battery and memory usage.

Sample Rate:
1, 2, 4 or 8Hz.
No of Samples:
Powers of 2, 128 - 4096 (more samples = better data)
Cycle Time:
Minimum cycle time is nearest whole number of minutes after processing has finished.
Delay Start:
Instrument can be programmed to begin sampling at a specific time.
Conditional:
Wave Sampling only occurs if pressure activity exceeds a
defined level.

Memory

The MIDAS DWR is fitted with 64Mb solid state non-volatile FLASH memory. Total capacity depends on setup. User may save any or all of the following: · Raw sensor data from each burst · Summary statistics of wave burst · Tide & additional sensor data · Spectral analysis of wave burst. If all data is saved, memory will typically record over 4000 data bursts. Sampling once every 2 hours, this is over 2 months data.

Software

System is supplied with WaveLog Express PC software, for instrument setup, data extraction and display. WaveLog Express is licence free.

Electrical

Internal:
32x D cells, 1.5V alkaline or 3.6V lithium
External:
9 – 30V DC
Power:
1.7W (sampling), <1mW (sleeping)
Battery Life:
Depends on sampling setup, typically:
>1 month operation (alkaline)
>2 months operation (lithium)
Connector:
SubConn Titanium MCBH10F

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 adapter
RS485 - Up to 1000m cable, addressable half duplex comms
Optional FSK
2 wire power & comms up to 6000m cable

Baud Rate: 2400 - 115200 (FSK fixed at 38400, USB 460800)
Protocol: 8 data bits, 1 stop bit, No parity, No flow control

Physical

Materials:
Acetal housing
optional stainless steel (316) cage
Depth Rating:
500m pressure sensor may be less
Size:
300mmØ x 290mm deep
Weight:
13Kg
Frame Size:
940 x 940 x 420mm
Frame Weight:
35kg

Ordering

0730035
MIDAS DWR Wave Recorder -
Piezo-Resistive type, supplied with:
0730036
MIDAS DWR Wave Recorder
Strain Gauge type,
Supplied with:
· SubConn switch plug,
· 3m communications lead,
· USB adapter, WaveLog Express software
· Manual, tool kit and transit case.
0730037
Stainless steel deployment cage
0400011
Optional Conductivity sensor
0400021B
Optional Turbidity sensor
0400021BI
Turbidity sensor interface

Product Enquiry

Valeport's Tide Range