摘要 |
<p>The dynamic sounding measurements are affected by the movement of the probe, which causes signal noise. The probe depth is related to an arbitrary reference surface and is changed in steps by a cable supporting the electrical supply conductors to the probe sensors, and the signal cables to retrieve the data. Readings are taken during the intervals between steps, by sensors capable of instantaneous response. In media partially filled with water, the depth is measured by hydrostatic pressure sensor. The system requires at least a power supply and a signal read-out unit, for example a recorder. It also includes a device for starting and stopping a programmed read-out sequence, a timer to initiate the sequence at regular intervals, and to advance the probe depth. There is an override for manual operation and therefore the cable will have markings at regular intervals. The measurements read-outs can also be monitored through audio signals.</p> |