Welcome back to our Wireless Radio series.
In this video,we will continue with where we left off
discussing wave modulation in Part 1,
“How does Wireless Radio Communication work?”,
where we also discussed electromagnetism
and how radio waves are transmitted and received.
You can find the link to this video in the description.
And now that we have a better understanding of electromagnetism
and how radio waves are generated,
let’s continue with this knowledge of wireless communication in our Part 2 video,
“How can we Improve Wireless Radio Modulation?”
In this video, we will discuss radio modulation,
what is pathloss and how to decrease it,
line of sight propagation, path profiles, and path profile engineering.
So, what exactly is modulation?
Modulation is a technique of converting and mixing data into radio waves
by adding this information to a carrier or base signal.
This is accomplished by a modulator in which,
mixes the data signal with a carrier signal.
A carrier wave is a wave of constant frequency, like a sine wave.
And as we have learned previously the transmitter
combines the modulated and amplified signals to the antenna,
which is specifically designed to emit this signal to the air.
The now modulated and amplified signal which emanates from the antenna
propagates through the air towards the receiving station antenna
where the modulated signal is demodulated,
separating the data from the carrier signal.
So, in other words, modulation alters the shape of a carrier wave
to encode the speech or sound and data information
we want to be transported by hopping on a normal signal wave.
A wave can be identified by its frequency,
measured in oscillation per second,
its wavelength measured in units of lengths
and its amplitude or power measured in “decibels” or “meters”.
This means the wavelength is inversely proportional to frequency,
in that, the longer the wavelength, will result in a lower frequency.
Or, the shorter the wavelength, will result in a higher frequency.
There are essentially three basic types of modulation,
Amplitude modulation, then there is Frequency modulation and finally, Phase modulation.
The difference between these modulation methods
is how the carrier wave is modulated, hence altered.
Let’s talk about the first two types.
Amplitude or AM modulation is where the amplitude of the carrier signal is modulated
or changed in proportion to the data signal.
And with Frequency or FM modulation,
the frequency, or the number of times per second the wave changes direction
determines how the carrier signal is modulated or altered.
Ok, now let’s discuss how far a radio wave will travel or propagate
and what are the elements interfering or attenuates the signal,
with a brief introduction to pathloss.
The transmitter radiates a signal
having a specific power based on the size and type of an antenna.
The signal as it travels begins to weaken or attenuate
based on the environment and landscape the signal travels.
The phenomenon known for how the electromagnetic wave weakens
is known as pathloss.
Radio waves are not aware of the exact path to a receiver
and therefore once transmitted
propagates in a direction of where antenna radiates the signal.
But the receiver only captures a certain portion of the signal
based on the power used at transmission
and depending on the different obstructive factors,
such as distance or free space,
obstacles such as buildings and mountains for example.
As electromagnetic waves propagate and travel further and further away,
the initial power at which the transmitted signals spreads out over a large area.
In the beginning, the entire transmitted power
is confined to a small spherical area or bubble.
To illustrate the degradation of the signal,
if the receiver is close to the transmitter
it will capture more power
and if the receiver is further away from the transmitter
the receiving antenna can only capture a smaller fraction of the transmitted power.
There are several parameters involved with attenuation,
they are distance, wavelength and the transmit power.
As we now know, the power of the signal reduces as the signal propagates
and so just to let you know,
the shorter waves or higher the frequency waves will experience higher attenuation.
Pathloss or L depends on distance and wavelength.
The greater the distance means lower power to be received
and with the wavelength, attenuation is greater for shorter wavelengths.
Power loss is the weakening of the signal no matter how much power is transmitted.
This means, if the path attenuation is 20dB
it will affect a strong signal in the same way as a weak signal.
However, if we transmit a weak signal and becomes attenuated,
even more, the demodulation of the signal becomes less reliable or even impossible.
How can we overcome path loss?
One way is to use an “RF Line-of-Sight” tool.
It allows us to easily drag and drop blue and green markers at different locations.
The tool then provides point to point line-of-sight information
anywhere using Google Maps for example.
Check out this free online tool from “SCADACORE”.
You can find the link to this tool in the description.
The “RF Line-of-Sight” tool is very helpful in mapping long distance radio communications
for remote SCADA monitoring remote sites and data acquisition applications.
The online tool considers antenna height and the topographical patterns of the earth
to calculate the line-of-sight of a radio path.
What about security,
isn’t this a concern with all this information transmitting out over free space?
Yes, and wireless network security becomes a very important factor
for IT and SCADA administrators to consider.
Soon the RealPars video,
“Wireless Security on the Plant Floor Explained” will be released.
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