Installation, Operation & Maintenance Manual
IP262/Z0, Rev. AB
February 2012 | MSL600 |
7.9.3.5Noise SD Mult – P635
The Municipal 1 algorithm scans the echo profile for echoes. Prior to sending pulses to the transducer, the noise floor is measured. It calculates the mean and standard deviation of fluctuations in the noise floor.
In order to be significant, the echo from a blanket must not only exceed a threshold value determined in terms of the standard deviation of the echo amplitudes (P634) but it must also exceed a threshold value determined in terms of the standard deviation of the noise floor (P635).
The default value is 2.75 standard deviations.
Parameter values:
Default | Min | Max |
2.75 | 0.00 | 9.99 |
7.9.3.6Dirty Mult – P636
It is often the case that the supernatant becomes dirty. In this case, large echoes can be seen directly in front of the transducer that should not necessarily be ignored or blanked out. If the amplitude of these signals is typically above 50% of the screen width, it is likely the supernatant was dirty and an alarm would be helpful in this situation. This can be achieved by programming a relay to operate in alarm mode and setting the alarm condition to Dirty
Parameter P636 is used to linearly scale the default threshold of 50%. The default value is a multiplier of 0.5, which represents 50% of the maximum displayable amplitude.
Parameter values:
Default | Min | Max |
0.5 | 0.00 | 2.00 |
7.9.3.7Lost Echo Time - P637
The Municipal 1 algorithm has a facility such that if the echo is lost from a set range (see P633) then the last reading is held for the programmed time. This allows the unit to accommodate any false echoes from targets other than the sludge blanket. In other words, the device is able to recognise that the sludge level does not change rapidly.
The parameter can be set between 1 to 255 minutes
Parameter values:
Default | Min | Max |
30 | 1 | 255 |
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