VEGA VEGAPULS 56V - Manual (Page 5)

VEGAPULS 56V 5
Time transformation
Pulse sequence
Meas. distance
emission - reflection - receipt
1 ns
278 ns
t t
Product description
The radar impulses are emitted by the an-
tenna system as impulse packets with a
pulse duration of 1 ns and pulse breaks of
278 ns; this corresponds to a pulse package
frequency of 3,6␣ MHz. In the impulse breaks
the antenna system operates as receiver.
Signal running periods of less than one mil-
lionth of a second must be processed and
the echo pictures must be evaluated in a
fraction of a second.
VEGAPULS radar sensors can reach this in a
special procedure of time transformation
which spreads more than 3,6 million echo
pictures per second in a slow motion picture,
then freezes and processes them.
Hence it is possible for the VEGAPULS 56
radar sensors to process the slow-motion
pictures of the sensor environment precisely
and in detail in cycles of 0,5 up to 1 second
without using very time consuming frequency
analysis (e.g. FMCW) necessary for other
radar principles.
Virtually all products can be measured
Radar signals physically react similar to vis-
ible light. According to the quantum theory
they penetrate empty space. Hence they are
not bound such as e.g. sound to a conduc-
tive product (air) and spread like with light
velocity. The radar signals react to two elec-
trical primary quantities:
- the electrical conductivity of a substance.
- the dielectric constant of a substance.
All products which are electrically conductive
reflect radar signals very well. Even only
slightly conductive products ensure a suffi-
cient signal reflection for a reliable measure-
ment.
All products with a dielectric constant
ε
r
of
more than 2,0 reflect radar impulses suffi-
ciently (note: air has a dielectric constant
figure
ε
r
of 1).
Reflected radar power dependent on the dielectric
constant figure of the measured product
2
0
0
10
25 %
40 %
5
10
5 %
20
30
40
50
%
4 6 8 12 14 16 18
20 r