AQUAscat
The AQUAscat 1000 represents a new generation of high frequency acoustic instrumentation. It has applications in sediment transport studies, including measurement of suspended sediment profiles, ripple bed morphology, precision altimetry, dredge plumes and turbulence.
 The AQUAscat transmits pulses of high frequency sound on up to four transducers, each of which may operate at a different frequency. It measures the sound scattered by sediment or other suspended materials at discrete spatial intervals programmable from 2½ millimetres to 4 centimetres. For altimetry, this may span a few tens of centimetres; for monitoring sediment suspension profiles, a total range of around 1- 2 metres is typical; while dredge plume estimation may extend to 10 metres. The instrument is supplied in a subsea housing suitable for long-term unattended deployments. There is also a laboratory version of the instrument, supplied in a bench-top instrument case. Batteries for various deployment schedules are available to order.
Specification
| Sediment Range |
Sensitive to grain sizes of less than 1 micron
Size inversion typically feasible for 20 micron to 500 micron radius
Typically 0.01 g/l to 20 g/l over 1 m, or more over shorter range |
| Frequencies |
Up to 4 frequencies, from 500 kHz to 5 MHz |
| Transducers |
Typically Ø10-25mm ceramic discs (beam width according to frequency), with other optional configurations |
| Transducer Arrangement |
AQUAscat 1000S: 4-frequency transducer head (0.5 / 1 / 2 / 4 MHz) integral to housing;
Other models: 4 connectors for individual cabled transducers |
| Gain |
Software controlled transmitter and receiver gain adjustment |
| Range |
150 cm (typical), up to 10 m below 2MHz depending on options and environment |
| Transmitted Signal |
1 W rms typical transmit CW pulse
Pulse length to match cell size |
| Transmission Rate |
128 Hz max pulse rate for each frequency (i.e. 512 pulses per second for four frequencies), subject to acoustic range limits. Minimum rate 1 Hz for calibration |
| Data Averaging |
Cell ensembles averaged over time by powers of 2 up to 64 before storage |
| Range Cells |
256 cells, 10 mm standard (at 1500 m/s speed of sound)
Options for 2.5 mm, 5 mm, 20 mm and 40 mm
Start/end range set by software |
| Burst Duration |
Defined by number of profiles requested |
| Burst Trigger |
Either external hardware trigger when required or internal software trigger at regular intervals |
| Burst Interval |
Internally generated from once every minute to once every 255 minutes, user definable start time of first burst |
| Trigger Output |
A digital output allows triggering of external instruments |
| Power Requirement |
8 V to 24 V dc
Typically 1 W when logging, and with standby of typically 1 mW when not logging |
| Battery Packs |
Internal alkaline battery pack gives 10 days typical low duty cycle deployment
External battery packs available according to deployment needs |
| Additional Sensors |
Temperature: -2 to +30°C standard, ±0.05°C, resolution <0.0015°C
Pressure: Choices to 100 bar, ±0.2%FS, resolution 0.005%FS
Turbidity: Optional remote turbidity sensor
Other: Connect up to two external sensors |
| Disk Storage |
Compact Flash (proprietary format)
4-8 GB standard |
| Data Comms |
RS232 up to 115 kbaud
USB 1.1 typically 2-3 Mbaud |
| Housing Options |
1000m rated aluminium alloy housing for subsea systems
Plastic IP68 bench-top instrument case for AQUAscat 1000L |
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AQUAscat
