User Manual

OPERATION

OPTIWAVE 7400-24 C

www.krohne.com12/2015 - 4004901901 - MA OPTIWAVE7400-24 R01 fr

6.4.8 How to make a filter to remove radar signal interference

If the device measures level in a tank that contains obstructions (agitator, supports, heating

pipes etc.), these objects can cause radar signal interference (parasitic signals). You can use the

empty spectrum function (menu item 2.1.2) in the Quick Setup menu to make a filter to remove

radar signal interference.

6.4.9 How to measure correctly in tanks with curved or conical bottoms

You can offset the tank bottom reference point to find the delayed radar reflection. Obey the

instructions that follow:

•

• Increase the tank height in menu C.1.2.

• Go to the signal screen

signal screensignal screen

signal screen in operator mode.

i You will see a graph of reflections.

• Push [>

>] to move the cursor to the reflection with the largest amplitude (given in dB).

• Make a note of the distance of the reflection measured by the device.

i The distance to the reflection will be the new tank height.

INFORMATION!

We recommend that you do an empty spectrum scan when the tank is empty and all the moving

parts (agitators etc.) are in operation..

Figure 6-7: How to make a filter to remove radar signal interference

1 Empty tank before the device uses the empty spectrum scan (with a graph of reflections shown)

2 Partially filled tank before the device uses the empty spectrum scan (with a graph of reflections shown)

3 Partially filled tank after the device uses the empty spectrum scan (with a graph of reflections shown)

4 Agitator blades location

5 Tank bottom signal

6 Agitator blades signals (interference signals) before the device does the empty spectrum scan

7 Bad quality (mixed) signals of the liquid and the agitator blades before the device does the empty spectrum scan

8 Reflected signal if the device uses the data from the empty spectrum scan. The device only uses the reflection on the

surface of the liquid to measure distance.

INFORMATION!

For more data on empty spectrum scans

–

table 2: Supervisor (menu item 2.1.2).