Image Processing Reference
In-Depth Information
Frequency spectrum use areas of
different processes/devices
WISA-POWER
WISA-COM
Arc welding
Spot welding
RFID, antitheft dev.
Induction heating
Switch mode power supplies
Motor contr. inverters
High HP motors
ISM transmitter
Contactors relays
10
100
1 k
10 k 100 k 1 M 10 M100 M 1 G
10 G 100 G
Frequency (Hz)
FIGURE .
Electromagnetic interference from typical applications in industry.
In the interference-free case, one in about uplink messages required a retransmission (marked
as “reference” in Figure .).
The effect on the WISA transmissions due to interference from other WISA base stations was also
measured in a realistic scenario. he antennas of the interfering base stations are set to point toward
the WISA system under test, thus simulating multicell operation as shown in Figure . (top).
28.4.3 Industrial Electromagnetic Interference
Investigation of a number of potential industrial sources of interference showed that no interference
is to be expected in the . GHz band from high power welding equipment or frequency converters.
Figure . gives an overview of typical industrial devices, their basic frequency, and indications for
their harmonics in the spectrum (Figure .).
The only interference may come from legal ISM transmitters. hey are not widespread but have to
be taken into account if unshielded. They can have very high power levels (e.g., microwave drying
applications in the kW range).
A spot welding gun used in induction welding, e.g., operates at up to kA and generates very high
electromagnetic field strengths. However, the majority of the high frequency noise decays strongly
above GHz and therefore has a minimal impact on WISA. he only measurable interference with
high frequencies (up to MHz) was identified as being generated by arc welding. WISA devices
have been tested with positions only a few centimeters away from the welding spots.
28.4.4 Interference from Other Communication Systems
A number of measurements and tests have been conducted to quantify the effect of interference
from other communication systems in the . GHz band. In a first scenario, interference was caused
