Page 36 February 2020 – TD 266 OPERATING MANUAL – ZPulse® DCS 4420/4830/4520/4930
Spread Mode
Burst Mode
Figure 2-19: Spread mode and burst mode ping distribution during the recording interval
Enable Single Interval is for use in Smart Sensor Terminal mode. If enabled and you send a Start command to the
sensor then the sensor will do one single recording before it enter sleep again. An alternative is to do a power reset
instead of the Start command. Note that if the sensor is in sleep when you switch off the power then it will be some time
before the sensor is discharged and you can put the power back on again to start a new interval. Alternatively you may
send a wake-up character to the sensor before power reset.
The transmitted pulse has a fixed length of 0.75m. Internal ringing in the transducers will always occur after transmitting
acoustic pulses; the transducers cannot receive backscattered signal until the ringing stops. For the ZPulse DCS the
pulse must have travelled at least a distance of minimum 0.4m before backscattered signals from the pulse can be
received by the transducers. This is called the Start Distance. The transducers continue to receive backscattered signal
from particles present in the beam until the pulse has propagated a distance equal to the Cell Size.
The total area from which the DCS receives backscattered energy is called the Measurement Area. Due to the shape of
the pulse, the main contribution to backscattered energy is from particles that are present in an area around the Cell
Centre. The measurement area outside the cell contributes very sparsely to the measured Doppler frequency shift.
Refer Figure 2-20 for an illustration.
Surrounding objects must be further away from the DCS than the described measurement area to avoid influencing the
measurements.
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