VEGA VEGAPULS 81 - Manual (Page 4)

4 VEGAPULS 64 and 81
Product description
1 Product description
1.1 Function
Radio detection and ranging: Radar.
VEGAPULS radar sensors are used for con-
tinuous and non-contact distance measure-
ment. The measured distance corresponds to
a filling height and is provided as level.
emission – reflection – receipt
Smallest 5,8 GHz radar signals are emitted
from the antenna of the radar sensor as short
pulses. The radar impulses reflected by the
sensor environment and the product are re-
ceived by the antenna as radar echoes. The
running period of the radar impulses from
emission to receipt is proportional to the dis-
tance and hence to the level.
VEGAPULS radar sensors can reach this in a
special procedure of the time transformation
which spreads more than 3,6 million echo
pictures per second in a slow-motion picture,
then freezes and evaluates them.
The radar pulses are emitted by the antenna
system as impulse packets with a pulse dura-
tion of 1 ns and impulse breaks of 278 ns; this
corresponds to a pulse package frequency of
3,6 MHz. In the pulse breaks the antenna
system operates as receiver. Hence signal
running periods of less than one millionth of a
second must be processed and the echo
pictures must be evaluated in a fraction of a
second.
Hence it is possible for the VEGAPULS radar
sensors to evaluate the slow-motion pictures of
the sensor environment precisely and in detail
in cycles of 0,1 seconds without using very
time consuming frequency analysis necessary
for other radar principles.
Virtually all products can be measured
Radar signals physically react similar to visible
light. According to the quantum theory they
penetrate empty space. Hence they are not
bound such as e.g. sound to a conductive
product (air) and spread like light with light
velocity. The radar signals react to two electri-
cal primary quantities:
- the electrical conductivity of a substance.
- the dielectric constant of a substance.
1 ns
278 ns
emission - reflection - receipt
Measur-
ing
distance
Time transformation
t t
Pulse sequence