Siemens Sitrans LR400 Instruction Manual page 96

Determining the Differential Frequency
frequency
Example
The linear frequency deviation is 200 MHz at a modulation duration of 10 ms. The surface
of the measuring medium is 10 m away from the transmitting antenna. The difference
signal then has a frequency of:
f
Every reflection at a surface generates a different frequency. The reception signal
therefore consists of a frequency mix from which the disturbance frequencies must be
filtered. These can be caused by fixed targets like struts inside the vessel.
Page 92 SITRANS LR400 (7ML5421) – INSTRUCTION MANUAL
f
d
B
t
T
⋅ ⋅ ⋅
8
2 2 10
--------------------------------- -
=
d
⋅ ⋅
3 –
10 3 10
10
,
= 13 333kHz
8
reception
transmission
signal
signal
time
7ML19985FH06