Number of discarded echoes: k (1, 3, 5, 10)
Under disadvantageous conditions (air movement, not perpendicular or bad
reflecting surfaces) some of the echoes may miss the sensor. Paying
immediate attention to this, might lead to frequent error indication and big
measurement errors. Therefore the unit first checks the measured distance to
verify that it is within range.
Measured distances outside the range will be disregarded during average
calculation and the output signal maintains the former value. The unit can
disregard k number of consecutive distance samples before an error will be
indicated.
If due to bad reflection a substantial number of echoes are lost and the number
of invalid (incorrect) echoes between two valid ones, is smaller than k the unit
will maintain the output signal continuously. The greater the programmed value
of k, the less sensitive the unit will be to invalid echoes but the reaction time for
error indication will increase. To maintain continuous operation the
programmed range should be kept as narrow as possible (with far-end
blocking).
The greater the speed of the target the smaller the chosen averaging number
should be. The worse the reflection of the target the higher the chosen value of
k (number of discarded echoes) should be.