Level/Distance measurements

Measurement duration

The duration of a single measurement. During this time the ultrasonic signal is recorded and the distance to the monitored surface calculated. Generally, a measurement duration of 6 s is recommended.

Level/distance test

Function to test the level/distance measurement. Initiates a measurement and returns the current distance and level.

Adjust level

Function to adjust the level measurement of the USH-9 to the actual level. It first initiates a measurement and then requests the actual level.

Distance to zero level

The distance between the sensors lower edge and the ground surface, e.g. lowest point of river bed, ground without snow.

Application

Switch to activate the settings for specific applications as listed in the following table:

ID	Option	Description
1	snow(default)	Settings for snow applications are active. These settings include precipitation detection and snowfall limits (see Status limits and Advanced settings). Rate of change filtering (RoC, max. without precip. (./h) and RoC, max. at precip. (./h)) is active.
2	water	Settings for water application are active. Precipitation detection and rate of change filtering (RoC) are deactivated.
3	others	Settings for water and snow applications are inactive. Used for generic level/distance measurements. A constant rate of change filter (Rate of change, maximum (./h)) is active.

ATTENTION  By default the USH-9 is configured for snow-depth measurements. If the instrument is used for water level monitoring, adapt its configuration as described in Configuring the USH-9 for water level measurements.

Moving filter, duration

Every level/distance measurement is stored internally in a buffer for filtering. This setting defines the length of the time window of which the data are stored in the buffer. If the buffer is full, the oldest value is replaced by the most recent one.

The figure below illustrates the default moving filter duration of 180 seconds. While a Measurement Interval of 90 seconds embraces two measurement values, an interval of 45 seconds includes 4 values.

Moving filter, type

The level/distance values in the buffer can be filtered by one of the following options:

ID	Option	Description
1	average	The mean value of all buffered values iss calculated.
2	elim. neg. spikes	To eliminate negative spikes, the mean value is calculated without the 5 lowest buffered values. If the buffer size is smaller than 10, half of the values are eliminated.
3	maximum	The highest value from the buffer is returned.
4	median	The median value of the buffered data is returned.
5	elim. pos. spikes	To eliminate positive spikes, the mean value is calculated without the 5 highest buffered values. If the buffer size is smaller than 10, half of the values are eliminated.
6	elim. all spike (default)	To eliminate positive and negative spikes, the mean value is calculated without the 5 highest and 5 lowest buffered values. If the buffer size is smaller than 15, two third of the values are eliminated.