Sequoia LISST-ABS, Руководство пользователя

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Section 2: Instructions
2.1 Introduction
Thank you for your purchase of Sequoia's LISST-ABS acoustic
backscatter sensor. The LISST-ABS is a single-point acoustic
sediment sensor, designed to provide higher quality data than
optical turbidity sensors. Its key advantages over optical
turbidity sensors are:

Superior response to particles of grain size >30 microns.

Relatively flat sensitivity to particles from 30-400 microns in
sizes.

Greater immunity to fouling.

Wide dynamic range of concentrations from 1mg/L to 30 g/L.
The LISST-ABS internally measures the Attenuation Corrected
Backscatter(ACB). The ACB value is converted to an
Uncalibrated Concentration (C
u
) and then output. To convert the
Uncalibrated Concentration to sediment concentration a simple
multiplier is required. The multiplier, or Cal Factor, is
dependent on the specific type and size of sediment being
measured. When a user recalibrates an instrument, it is this
multiplier that is updated. For more detailed understanding of
the technology, please see
Appendix C
.
The LISST-ABS can output the Uncalibrated Concentration
using three different methods, SDI-12, RS232, and analog
output. All three of these outputs are available on the
underwater connector on the end of the LISST-ABS. The
output used is determined by how the instrument is connected
to a datalogger.
The LISST-ABS can be powered in two ways. For testing
purposes, a special USB cable is available. When using this
cable, power to the instrument is provided by the USB port.
When connecting to a datalogger you will need to supply a
voltage between 10-18VDC. The current drain at 12V is 100
ma when actively collecting data. If the supply voltage is too
low the LISST-ABS will output an Uncalibrated Concentration
value of -999.
When the LISST-ABS is powered up the green LED on the
endcap will start to blink at about once per second. This
indicates the instrument is powered up and operating normally.
When the LISST-ABS is actively sampling it will double blink
(two blinks in quick succession). When idle but still powered up
it will do a single blink once per second.