Did you know that wireless communication has been used in industrial applications
for over 30 years?
Yes, and some of the first applications were the wireless control
of “Automated Guided Vehicles” and “Warehouse Cranes”.
Wireless technologies have become progressively widespread
in industrial automation applications
for solutions with system integrators, government agencies, and industrial companies.
And over the last 10 years, radio technologies have become standardized,
like Wireless LAN, and Bluetooth technology
in which have become leading technologies for industrial automation applications.
A powerful advantage with wireless networks
is that they can be deployed easily to transmit data to areas
eliminating the requirement to run expensive cable infrastructures.
And in addition to location flexibility,
wireless technologies offer real time communication for applications
such as with SCADA and RTU communications,
high bandwidth for video transmission used for remote security
and offers a lower total cost of ownership.
Have you ever wondered how information like text messages,
pictures, videos, and voice moves between wireless connected phones,
computers, laptops and cameras?
It’s magical to most
but can be realized when we learn about the invisible force
performing all the work called electromagnetism.
Electromagnetism is the creation of a magnetic field from the movement
of electrically charged particles
or movement or interaction between electricity and magnetism
such as when a changing electric field generates a magnetic field
or with the inverse when a changing magnetic field generates an electric field.
This same force is used to transmit radio waves when alternating electric current flows,
propagating the signal through internal wires into a transmitting antenna
which in turn makes electrons vibrate producing radio waves.
Essentially, the antenna radiates the alternating current as an electromagnetic wave,
this is where wireless transmission starts.
When the radio waves travel through the air at the speed of light
and when these waves reach the receiving antenna,
they, in turn, make electrons vibrate within it,
reproducing the same waveform generated by the transmitting radio.
During the time at (1) electricity flows into the transmitting antenna
and makes electrons vibrate up and down creating radio waves.
The radio waves begin to travel at (2) through the air at the speed of light
and when the waves reach the receiving antenna at (3)
they make electrons vibrate inside it
and this, in turn, produces an electric current
that recreates the original sound or data.
The frequency or alternating waveform of the signal
changes based on how fast the signal from the transmitter is output,
creating waves with different frequencies.
Various frequencies can be used for different purposes.
We call a range of different frequencies a spectrum
and are divided into areas of specific usage or bands.
Frequency is about how many electromagnetic waves
pass through a point of reference every second.
This is measured by counting the peaks of each wave
which will be measured in units of Hertz or cycles per second.
Wavelength is the distance measured between the two highest peaks in a wave,
this distance is referred to as a period.
Wavelengths could be smaller than the size of an atom
and longer than the diameter of the planet earth!
Within this electromagnetic band of different frequencies,
radio waves have the longest wavelengths and the lowest frequencies
which allows them to travel the farthest.
The different spectrum of bands allows FM and AM radio waves,
cell phone signals, WiFi signals, and a lot more to share the same space
because they are grouped within specific frequency ranges.
Some of the specific frequency bands you may be aware of are:
ELF or Extremely low frequency with a frequency of “3–30 Hz”
and a wavelength of “105–104 km”.
and VHF or Very high frequency with a frequency of “30–300 MHz”
and a wavelength of “10–1 m”.
and UHF or Ultra high frequency with a frequency of “300 MHz to 3 GH”
and a wavelength of “1 m to 10 cm.
And just so you know, in the US,
authorities like the Federal Communications Commission or FCC,
or the European Electronic Communications Committee or ECC,
are responsible for assigning frequency ranges for specific usage.
An electromagnet signal does not go straight out to a receiver after being transmitted
but radiates the signal in multiple directions.
Radio waves can reflect off buildings,
they can bend on sharp edges or even scatter on small objects
and still be able to reach the receiver.
During the journey, waves radiated from multiple paths
endure different types of attenuation or weakening and delay.
The receiving antenna captures all the waves as a combined signal
and when the wave travels more than one route it is called a multipath channel.
This multipath generated combined signal, now distorted and mixed
must be decoded by the receiver to read the data generated.
This is not easily accomplished
since the received signal contains a lot of unwanted anomalies.
So, to make the receiver’s job easier we add some additional steps before transmission.
Before sending any data, the transmitting components perform the encoding.
The encoding operation appends additional bits into the message
which makes the data recovery at the receiver much simpler.
After the encoding digital data are mapped onto symbols
then modulated by varying the signal amplitude
and then passed to the transmitting antenna.
This concludes, “How does Industrial Wireless Communication work Part 1 of 2”.
In the next part, we will discuss more about modulation,
radio path loss, line of sight propagation,
path profile engineering to help radio propagation.
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