0106804 b - Model 106 Current Meter - Operating Manual
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2019 – Valeport Ltd
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2.
System Description
2.1.
Instrument - Model 106
The instrument contains all of the measurement sensors and electronics. The current meter works on a basic
1-second cycle, during which the impeller counts are taken and a single compass heading reading is made.
From this, East and North velocity vectors are calculated, which are then summed over the averaging period.
The additional parameters of temperature and pressure (if fitted) are sampled once every sample period, and
averaged over the averaging period.
Note that at very low flow speeds (of the order of a few centimetres per second), it will be necessary to set a
reasonably long averaging period to improve the resolution and accuracy of the flow measurements.
The Model 106 is fitted with a data acquisition micro-controller, operating at 12-bit resolution. The
temperature and depth sensors operate on a basic 16 Hz sampling rate and the samples are sequential.
When in Self-Recording mode, the instrument logs raw data. In real time mode, the calibration constants in
the instrument software are used to calculate the actual temperature and pressure readings within the
instrument, and the 8008 Surface Unit or PC reads this data. When logged data is extracted, the raw data is
transferred to the PC and then the Windows software automatically converts the data to engineering units.
This operation is covered in the supplementary software manual.
Optional sensors that can be fitted are a thermistor temperature sensor and strain gauge pressure
transducer. The type and range of transducer actually fitted is defined in the calibration sheet.
