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FAQ
How to set up parameters to avoiding false altitude
Revised 11/18/2021
In order to have a real Altitude at appx. 6.0m (2)
èIncrease Deadzone to ~500mm in order to avoid the first peak (1)
èOr increase Altimeter Threshold (yellow dotted line)
so that the threshold can meet the real peak (2) first, not peak (1)
The rules of thumb are,
-Set the Deadzone big enough to avoid initial reverberation (1)
-In Altimeter modes (Simple, NMEA, PSA-916) increase the Gain, so that the Echo signal
can be big enough (saturated). This will help to keep the Echo signal amplitude minimizing
fluctuation. But also watch other unwanted reflections amplified by this Gain.
-The Threshold should be as small as possible. But it should be more than the unwanted
signals, otherwise false values will be calculated from these unwanted reflections, not from
the bottom of the water. This is when users feel the altitude values from the device are not
accurate, but this is a matter of setting optimal parameters using Echogram at Echosounder
mode (not at Altimeter mode)
*Example of settings – Altimeter mode for altitude measurement
ECT400, ECS400, EU400 (450kHz):
Tx Length: 100 µsec
Deadzone: 300 mm
Threshold: 10%
Gain: +10 dB
Offset : +35 mm (when altitude from the front face of the transducer is required) Speed of
sound :1,480 m/s (fresh water at 20degC)
Make the most of the Echogram, where real-time echo signal is shown. The
altitude is determined where the threshold meets the first echo-signal. For accurate
altitude data appropriate Threshold, Dead zone and Gain have to be chosen.