In this video, I will explain what is QAM modulation and what is 16QAM.
QAM Stands for Quadrature Amplitude Modulation. QAM is both an analog and a digital modulation method. But here, we are only talking about QAM as a digital modulation.
Quadrature means that two carrier waves are being used, one sine wave and one cosine wave. These two waves are out of phase with each other by 90°, this is called quadrature.
At the receiving end, the sine and cosine wave can be decoded independently, this means that by using both a sine wave and a cosine wave, the communication channel's capacity is doubled comparing to using only one sine or one cosine wave. That is why quadrature is such a popular technique for digital modulation.
QAM modulation is a combination of Amplitude Shift Keying and Phase Shift Keying, both carrier wave is modulated by changing both its amplitude and phase. As shown in this 8QAM waveform, the top is the sine wave carrier, for bit 000, the sin wave has a phase shift of 0°, and an amplitude of 2. While for bit 110, the phase shift is 180°, and the amplitude now is 1. So both phase and amplitude are changed.
In 16QAM, the input binary data is combined into groups of 4 bits called QUADBITS.
As shown in this picture, the I and I' bits are sent to the sine wave modulation path, and the Q and Q' bits are sent to the cosine wave path. Since the bits are split and sent in parallel, so the symbol rate has been reduced to a quarter of the input binary bit rate. If the input binary data rate is 100 Gbps, then the symbol rate is reduced to only 25 Gbaud/second. This is the reason why 16QAM is under hot research for 100Gbps fiber optic communication.
The I and Q bits control the carrier wave's phase shift, if the bit is 0, then the phase shift is 180°, if the bit is 1, then the phase shift is 0°.
The I' and Q' bits control the carrier wave's amplitude, if bit is 0, then the amplitude is 0.22 volt, if the bit is 1, then the amplitude is 0.821 volt.
So each pair of bits has 4 different outputs. Then they are added up at the linear summer. 4X4 is 16, so there is a total of 16 different combinations at the output, that is why this is called 16QAM.
This illustration shows an example of how the QUADBIT 0000 is modulated onto the carrier waves.
Here I and I' is 00, so the output is -0.22 Volt at the 2-to-4-level converter, when timed with the sine wave carrier, we get -0.22sin(2πfct), here fc is the carrier wave's frequency. QQ' is also 00, so the other carrier wave output is -0.22cos(2πfct).
Here is the proof that quadbit 0000 is modulated as a sine wave with an amplitude of 0.311volt and a phase shift of -135°. You can now pause for a moment to study the proof.
This list shows the 16QAM modulation output with different amplitude and phase change for all 16 quadbits. On the right side is the constellation diagram which shows the positions of these quadbits on a I-Q diagram.
You can visit FO4SALE.com f
The Quadrature Phase Shift Keying QPSK is a variation of BPSK, and it is also a Double Side Band Suppressed Carrier DSBSC modulation scheme, which sends two bits of digital information at a time, called as bigits.
Instead of the conversion of digital bits into a series of digital stream, it converts them into bit pairs. This decreases the data bit rate to half, which allows space for the other users.
QPSK (Quadrature Phase Shift Keying) is type of phase shift keying. Unlike BPSK which is a DSBCS modulation scheme with digital information for the message, QPSK is also a DSBCS modulation scheme but it sends two bits of digital information a time (without the use of another carrier frequency).
The amount of radio frequency spectrum required to transmit QPSK reliably is half that required for BPSK signals, which in turn makes room for more users on the channel.
In this video, I will explain what is QAM modulation and what is 16QAM.
QAM Stands for Quadrature Amplitude Modulation. QAM is both an analog and a digital modulation method. But here, we are only talking about QAM as a digital modulation.
Quadrature means that two carrier waves are being used, one sine wave and one cosine wave. These two waves are out of phase with each other by 90°, this is called quadrature.
At the receiving end, the sine and cosine wave can be decoded independently, this means that by using both a sine wave and a cosine wave, the communication channel's capacity is doubled comparing to using only one sine or one cosine wave. That is why quadrature is such a popular technique for digital modulation.
QAM modulation is a combination of Amplitude Shift Keying and Phase Shift Keying, both carrier wave is modulated by changing both its amplitude and phase. As shown in this 8QAM waveform, the top is the sine wave carrier, for bit 000, the sin wave has a phase shift of 0°, and an amplitude of 2. While for bit 110, the phase shift is 180°, and the amplitude now is 1. So both phase and amplitude are changed.
In 16QAM, the input binary data is combined into groups of 4 bits called QUADBITS.
As shown in this picture, the I and I' bits are sent to the sine wave modulation path, and the Q and Q' bits are sent to the cosine wave path. Since the bits are split and sent in parallel, so the symbol rate has been reduced to a quarter of the input binary bit rate. If the input binary data rate is 100 Gbps, then the symbol rate is reduced to only 25 Gbaud/second. This is the reason why 16QAM is under hot research for 100Gbps fiber optic communication.
The I and Q bits control the carrier wave's phase shift, if the bit is 0, then the phase shift is 180°, if the bit is 1, then the phase shift is 0°.
The I' and Q' bits control the carrier wave's amplitude, if bit is 0, then the amplitude is 0.22 volt, if the bit is 1, then the amplitude is 0.821 volt.
So each pair of bits has 4 different outputs. Then they are added up at the linear summer. 4X4 is 16, so there is a total of 16 different combinations at the output, that is why this is called 16QAM.
This illustration shows an example of how the QUADBIT 0000 is modulated onto the carrier waves.
Here I and I' is 00, so the output is -0.22 Volt at the 2-to-4-level converter, when timed with the sine wave carrier, we get -0.22sin(2πfct), here fc is the carrier wave's frequency. QQ' is also 00, so the other carrier wave output is -0.22cos(2πfct).
Here is the proof that quadbit 0000 is modulated as a sine wave with an amplitude of 0.311volt and a phase shift of -135°. You can now pause for a moment to study the proof.
This list shows the 16QAM modulation output with different amplitude and phase change for all 16 quadbits. On the right side is the constellation diagram which shows the positions of these quadbits on a I-Q diagram.
You can visit FO4SALE.com f
The Quadrature Phase Shift Keying QPSK is a variation of BPSK, and it is also a Double Side Band Suppressed Carrier DSBSC modulation scheme, which sends two bits of digital information at a time, called as bigits.
Instead of the conversion of digital bits into a series of digital stream, it converts them into bit pairs. This decreases the data bit rate to half, which allows space for the other users.
QPSK (Quadrature Phase Shift Keying) is type of phase shift keying. Unlike BPSK which is a DSBCS modulation scheme with digital information for the message, QPSK is also a DSBCS modulation scheme but it sends two bits of digital information a time (without the use of another carrier frequency).
The amount of radio frequency spectrum required to transmit QPSK reliably is half that required for BPSK signals, which in turn makes room for more users on the channel.
Design and implementation of qpsk modulator using digital subcarrierGongadi Nagaraju
The digitally implemented QPSK modulator is developed for satellite communication for future satellite missions. As we know that for space application power and bandwidth are most important parameters.The size of PCB and component count are also important parameters. To reduce these all parameters we design new approach. The new approach also minimizes the component count and hence reduces the PCB size. In this modulator summation, orthogonal sub-carrier generation and mixing of subcarrier with data are all digitally implemented inside the FPGA
Frequency-Shift Keying, also known as FSK is a type of digital frequency modulation. It is also often called as binary frequency shift keying or BFSK
Similar to analog FM, it is a constant-amplitude angle modulation.
This presentation will discuss the concepts behind FSK
Design and implementation of qpsk modulator using digital subcarrierGongadi Nagaraju
The digitally implemented QPSK modulator is developed for satellite communication for future satellite missions. As we know that for space application power and bandwidth are most important parameters.The size of PCB and component count are also important parameters. To reduce these all parameters we design new approach. The new approach also minimizes the component count and hence reduces the PCB size. In this modulator summation, orthogonal sub-carrier generation and mixing of subcarrier with data are all digitally implemented inside the FPGA
Frequency-Shift Keying, also known as FSK is a type of digital frequency modulation. It is also often called as binary frequency shift keying or BFSK
Similar to analog FM, it is a constant-amplitude angle modulation.
This presentation will discuss the concepts behind FSK
Power point presentation of Amplitude modulation from DSBSC.pptxvairaprakash3
The equation of AM wave in simple form is given by,
eAM(t) = Ec sin 2πfct+(mE_c)/2 cos2π(fc + fm)t - (mE_c)/2 cos2π(fc - fm)t
Here, power of the carrier does not convey any information. Most of the power is transmitted in the carrier is not used for carrying information. Hence the carrier is suppressed and only sidebands are transmitted.Therefore, if the carrier is suppressed, only sidebands remain in the spectrum requiring less power.
DSB-SC Contains two side bands i.e USB & LSB
Power efficiency is 100%
% Power saving in DSB-SC w.r.t AM is 66.67%.
the modulation of a wave by varying its amplitude, used especially as a means of broadcasting an audio signal by combining it with a radio carrier wave.
SSBSC Single Side Band - Suppressed Carrier CompressedArijitDhali
This PowerPoint presentation is all about the definition of SSBSC or Single Side Band Suppressed Carrier. It consists of rich visuals along with the technique of modulation. Also a simplified version of derived expressions help the student to understand more about the topic. Moreover its suitable for students aiming for electronics and communication engineering.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
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Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
3. 3
Single Side Band Suppressed Carrier
From DSB-SC spectrum:
• Information ωm is carried twice
• Bandwidth is is high
ωc - ωm ωc ωc + ωm
Carrier
USBLSB
Single frequency
Question: Why transmit both side bands?
Ans:
Question: Can one suppress one of the side bandcarrier?
Ans.: Yes, just transmit one side band (i.e SSB-SC)
System complexity at the receiver
But what is the penalty?
4. 4
SSB-SC - Implementation
• Frequency discrimination
MultiplierMultiplier
Message
m(t)
Local oscillator
c(t) = cos ωct
Local oscillator
c(t) = cos ωct
DSB-SC
t
ME
t
ME
ttEtc
mc
c
mc
c
cmm
)(cos
2
)(cos
2
coscos)(
ω−ω+ω+ω=
ωω=
Band pass
filter
ωc+ ωc
Band pass
filter
ωc+ ωc
Band pass
filter
ωc- ωc
Band pass
filter
ωc- ωc
t
ME
tc mc
c
)(cos
2
)( ω+ω=
t
ME
tc mc
c
)(cos
2
)( ω−ω=
Upper sideband
Lower sideband
6. 6
SSB-SC - Implementation cont.
• Phase discrimination (Hartley modulator)
XX
SSB-SC
signal
XX
Em sin ωmt sin ωct
sin ωct
cos ωctCarrierCarrier
90o
phase shift
90o
phase shift
Message
m(t)
90o
phase shift
90o
phase shift
∑∑
+
-
Em cos ωmt cos ωct
Em sin ωmt
Em cos ωmt
v(t) =Em cos ωmt cos ωct + Em sin ωmt sin ωct
= Em cos (ωm - ωc)t LSB
v(t) =Em cos ωmt cos ωct + Em sin ωmt sin ωct
= Em cos (ωm - ωc)t LSB
v(t) =Em cos ωmt cos ωct - Em sin ωmt sin ωct
= Em cos (ωm + ωc)t USB
v(t) =Em cos ωmt cos ωct - Em sin ωmt sin ωct
= Em cos (ωm + ωc)t USB
7. 7
SSB-SC - Hartley Modulator
• Advantages:
– No need for bulky and expensive band pass filters
– Easy to switch from a LSB to an USB SSB output
• Disadvantage:
– Requires Hilbert transform of the message signal. Hilbert
transform changes the phase of each +ve frequency
component by exactly - 90o
.
8. 8
SSB-SC - Detection
• Synchronous detection
MultiplierMultiplier
Low
pass
filter
Low
pass
filter Message signal
SSB-SC
Local oscillator
c(t) = cos ωct
Local oscillator
c(t) = cos ωct
Condition:
•Local oscillator has the same
frequency and phase as that of the
carrier signal at the transmitter.
ωm 2ωc+ωm
Low pass filter
high frequencyinformation
tt
ME
ty cmc
c
ω∗ω+ω= cos)(cos
2
)(
t
ME
t
ME
ty mc
c
m
c
)2(cos
4
)(cos
4
)( ωωω ++−=
t
ME
tv m
c
ω= cos
4
)(
9. 9
SSB-SC - Synch. Detection cont.
• Case 1 - Phase error
MultiplierMultiplier
Low
pass
filter
Low
pass
filter Message signal
SSB-SC
Local oscillator
c(t) = cos (ωct+θ)
Local oscillator
c(t) = cos (ωct+θ)
Condition:
•Local oscillator has the same
frequency but different phase as
that of the carrier signal at the
transmitter.
ωm 2ωc+ωm
Low pass filter
high frequencyinformation
)(cos)(cos
2
)( θ+ω∗ω+ω= tt
ME
ty cmc
c
)2(cos
4
)(cos
4
)( θωωθω +++−= mc
c
m
c
t
ME
t
ME
ty
t
ME
tv m
c
)(cos
4
)( θ−ω=
10. 10
SSB-SC - Synch. Detection cont.
• Case 1 - Frequency error
MultiplierMultiplier
Low
pass
filter
Low
pass
filter Message signal
SSB-SC
Local oscillator
c(t) = cos
(ωc+∆ω)t
Condition:
•Local oscillator has the same
phase but different frequency as
that of the carrier signal at the
transmitter.
ωm +∆ω 2ωc+ωm +∆ω
Low pass filter
high frequencyinformation
tt
ME
ty cmc
c
)(cos)(cos
2
)( ω∆+ω∗ω+ω=
t
ME
t
ME
ty mc
c
m
c
)2(cos
4
)(cos
4
)( ωωωωω ∆+++∆−=
t
ME
tv m
c
)(cos
4
)( ω∆−ω=
11. 11
SSB-SC - Power
• The total power (or average power):
R
ME
ME
R
P
c
c
SCSSBT
8
)(
2
2/1
2
2
=
=−−
• The maximum and peak envelop power
2
4
)(
R
ME
P c
SCSSBP =−−
12. 12
SSB-SC - Summary
• Advantages:
– Lower power consumption
– Better management of the frequency spectrum
– Less prone to selective fading
– Lower noise
• Disadvantage:
- Complex detection
• Applications:
- Two way radio communications
- Frequency division multiplexing
- Up conversion in numerous telecommunication systems
