1. Digital modulation techniques are used to modulate digital information so that it can be transmitted via different mediums. Common digital modulation methods include binary amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK).
2. FSK conveys information by changing the instantaneous frequency of a carrier wave. It is less susceptible to errors than ASK but has a larger spectrum bandwidth. PSK varies the phase of the transmitted signal. BPSK uses two phases while QPSK uses four phases.
3. The performance of digital modulation techniques can be compared using the energy per bit to noise power spectral density ratio (Eb/N0). Lower Eb/N0 values
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
Phase-shift keying (PSK) is a digital modulation scheme that conveys data by changing (modulating) the phase of a reference signal (the carrier wave). The modulation is impressed by varying the sine and cosine inputs at a precise time. It is widely used for wireless LANs, RFID and Bluetooth communication
Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal.[1] The technology is used for communication systems such as amateur radio, caller ID and emergency broadcasts
It is a digital representation of an analog signal that takes samples of the amplitude of the analog signal at regular intervals. The sampled analog data is changed to, and then represented by, binary data.
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
Phase-shift keying (PSK) is a digital modulation scheme that conveys data by changing (modulating) the phase of a reference signal (the carrier wave). The modulation is impressed by varying the sine and cosine inputs at a precise time. It is widely used for wireless LANs, RFID and Bluetooth communication
Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal.[1] The technology is used for communication systems such as amateur radio, caller ID and emergency broadcasts
It is a digital representation of an analog signal that takes samples of the amplitude of the analog signal at regular intervals. The sampled analog data is changed to, and then represented by, binary data.
In digital modulation, minimum-shift keying(MSK) is a type of continuous-phase frequency-shift keying that was developed in the late 1950s and 1960s.
Similar to OQPSK(Offset quadrature phase-shift keying),
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.
The most fundamental digital modulation techniques are based on keying: PSK (phase-shift keying): a finite number of phases are used. FSK (frequency-shift keying): a finite number of frequencies are used. ... QAM (quadrature amplitude modulation): a finite number of at least two phases and at least two amplitudes are used.
This presentation covers:
Some basic definitions & concepts of digital communication
What is Phase Shift Keying(PSK) ?
Binary Phase Shift Keying – BPSK
BPSK transmitter & receiver
Advantages & Disadvantages of BPSK
Pi/4 – QPSK
Pi/4 – QPSK transmitter & receiver
Advantages of Pi/4- QPSK
In communication system, intersymbol interference (ISI) is a form of distortion of a signal in which one symbol interferes with subsequent symbols. This is an unwanted phenomenon as the previous symbols have similar effect as noise, thus making the communication less reliable.
In communication system, the Nyquist ISI criterion describes the conditions which when satisfied by a communication channel (including responses of transmit and receive filters), result in no intersymbol interference(ISI). It provides a method for constructing band-limited functions to overcome the effects of intersymbol interference.
Base band transmission
*Wave form representation of binary digits
*PCM, DPCM, DM, ADM systems
*Detection of signals in Gaussian noise
*Matched filter - Application of matched filter
*Error probability performance of binary signaling
*Multilevel base band transmission
*Inter symbol interference
*Eye pattern
*Companding
*A law and μ law
*Correlation receiver
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In digital modulation, minimum-shift keying(MSK) is a type of continuous-phase frequency-shift keying that was developed in the late 1950s and 1960s.
Similar to OQPSK(Offset quadrature phase-shift keying),
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.
The most fundamental digital modulation techniques are based on keying: PSK (phase-shift keying): a finite number of phases are used. FSK (frequency-shift keying): a finite number of frequencies are used. ... QAM (quadrature amplitude modulation): a finite number of at least two phases and at least two amplitudes are used.
This presentation covers:
Some basic definitions & concepts of digital communication
What is Phase Shift Keying(PSK) ?
Binary Phase Shift Keying – BPSK
BPSK transmitter & receiver
Advantages & Disadvantages of BPSK
Pi/4 – QPSK
Pi/4 – QPSK transmitter & receiver
Advantages of Pi/4- QPSK
In communication system, intersymbol interference (ISI) is a form of distortion of a signal in which one symbol interferes with subsequent symbols. This is an unwanted phenomenon as the previous symbols have similar effect as noise, thus making the communication less reliable.
In communication system, the Nyquist ISI criterion describes the conditions which when satisfied by a communication channel (including responses of transmit and receive filters), result in no intersymbol interference(ISI). It provides a method for constructing band-limited functions to overcome the effects of intersymbol interference.
Base band transmission
*Wave form representation of binary digits
*PCM, DPCM, DM, ADM systems
*Detection of signals in Gaussian noise
*Matched filter - Application of matched filter
*Error probability performance of binary signaling
*Multilevel base band transmission
*Inter symbol interference
*Eye pattern
*Companding
*A law and μ law
*Correlation receiver
This presentation contain each and every single information on the topic.
If you like it do follow and like my presentation.
It would be worth my efforts.
introduce the basic modulation tech (PSK, FSK, QAM etc)
and comparison between them.
ref : Communication System (4ed, Haykin)
this ppt is for my seminar
This slide describe the techniques of digital modulation and Bandwidth Efficiency:
The first null bandwidth of M-ary PSK signals decrease as M increases while Rb is held constant.
Therefore, as the value of M increases, the bandwidth efficiency also increases.
Design and analysis of different digital communication systems and determinat...eSAT Journals
Abstract For a specialized device or set-up in case of any practical communication related problem definition, a sound communication system consisting of the necessary integral parts is very crucial. As such, the design and an analysis of the various communication system is very critical as it directly effects the performance of the device and also reveals the inherent capacity of the system to produce the desired results. In this respect our topic for this paper is the design and analysis of different digital communication systems with a view to determine the most effective system considering all the parameters so that it can be used for important communication based problems and situations. In the next section we will mainly focus on the design processes of various systems, the theory involved, the simulation results, some special techniques of error correction and also the error performance of the systems. Keywords- modulation, digital, communication systems, shift keying, error performance, SNR
Design and analysis of different digital communication systems and determinat...eSAT Journals
Abstract For a specialized device or set-up in case of any practical communication related problem definition, a sound communication system consisting of the necessary integral parts is very crucial. As such, the design and an analysis of the various communication system is very critical as it directly effects the performance of the device and also reveals the inherent capacity of the system to produce the desired results. In this respect our topic for this paper is the design and analysis of different digital communication systems with a view to determine the most effective system considering all the parameters so that it can be used for important communication based problems and situations. In the next section we will mainly focus on the design processes of various systems, the theory involved, the simulation results, some special techniques of error correction and also the error performance of the systems. Keywords- modulation, digital, communication systems, shift keying, error performance, SNR
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IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Comparative Study and Performance Analysis of different Modulation Techniques...Souvik Das
A comparative study and performance analysis of different modulation
techniques which shows graphically and comparative results Channel Noise
with Bit Error Rate of ASK, FSK, PSK and QPSK.
Digital Communication System
Communication Channels
AWGN: Universal channel model
Band Limited Channel: Channel BW <Signal BW, ISI
Fading Channel: multipath waves
Basic Modulation Methods
Criteria for choosing Modulation Schemes
Power Efficiency: Required Eb/N for certain error probability over AWGN channel
Bandwidth Efficiency: no. of bits per second that can be transmitted on system bandwidth.
System Complexity: Amount of circuit involved and complexity
System Performance Parameters
Average SNR
Outage Probability: instantaneous prob. Exceed certain limit
Average BEP
Amount of Fading/severity of fading
Average Outage duration: O/P SNR fall below certain SNR
Analog-to-digital conversion (ADC) is an electronic process in which a continuously variable, or analog, the signal is changed into a multilevel digital signal without altering its essential content.
International Journal of Engineering Research and Applications (IJERA) aims to cover the latest outstanding developments in the field of all Engineering Technologies & science.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
This presentation include the basic concept of communication, modulation techniques in analog and digital. ADC (Analog to Digital Conversion) and Demodulation schemes
Orthogonal frequency-division multiplexing (OFDM)
[1] is a method of encoding digital data on multiple carrier
frequencies. OFDM[1] has developed into a popular scheme
for wideband digital communication, whether wireless or
over copper wires, used in applications such as digital television
and audio broadcasting, DSL Internet access, wireless networks,
powerline networks, and 4G mobile communications. In the
Several wireless standards such as IEEE 802.11a[2] and
HiperLAN2[3].The orthogonality of the subcarriers is no longer
maintained which results in ICI (Inter carrier Interference)[4]
.ICI reduction techniques achieve a better SNR and BER in
OFDM at zero phase noise variance . This technique will use a
large number of closely spaced orthogonal subcarriers to avoid
phase noise. It provides high data rates with sufficient robustness
to radio channel damages. A major problem in OFDM is carrier
frequency offset error between the transmitted and received
signals. Due to this the orthogonality of the subcarriers is no
longer maintained which results in ICI (Inter carrier
Interference). In this paper, we used the ICI self-cancellation
technique and reduced the ICI and improved the BER and SNR
we are also calculate the SNR=15db and 20db at different phase
noise variance.
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ASk,FSK,PSK
1. An Najah National University
Telecommunication Engineering Department
comparison of binary shift keying techniques
Prepeared by : Suhad Malayshi
Raghad foqha
Ola mashaqi
submitted to Dr. Allam Mousa
2. What is digital modulation?
The techniques used to modulate digital information so that it can be transmitted
via microwave, satellite or down a cable pair are different to that of Analogue
transmission .
3. Fundamental digital modulation methods:
Binary Amplitude shift keying (on-off keying)
advantage: simplicity
•disadvantage: ASK is very
susceptible to noise interference–
noise usually (only)affects the
amplitude, therefore ASK is the
modulation technique most
affected by noise
•application: ASK is used to
transmit digital data over optical
fiber
4. Frequency Shift Keying
Frequency Shift Keying (FSK) is a frequency modulation scheme (conveys
information over a carrier wave by varying its instantaneous frequency)
in which digital information is transmitted through discrete frequency
changes of a carrier wave .
5. FSK is the most common form of digital modulation in the high frequency radio
spectrum, and has important applications in telephone cct.
A modem converts the binary data from a computer to FSK for transmission
over telephone lines, cables, or wireless media.
Shifts are usually in the range of 50 to 1000Hz.
demodulation:
demodulator must be able to determine which of two possible frequencies is
present at a given time
advantage:
FSK is less susceptible to errors than ASK – receiver looks for specific frequency
changes over a number of intervals, so voltage (noise) spikes can be ignored
disadvantage:
FSK spectrum is 2 x ASK spectrum
application:
over voice lines, in high-freq. radio transmission, etc.
6. BFSK ( Binary Frequency Shift Keying )
General form of BFSK is :
0),2cos(
1),2cos(
)(
2
1
binarytfA
binarytfA
ts
Here , in BFSK, the “1” is called the mark frequency and the “0” is called the space
frequency.
The optical field of FSK form is :
The total B.W of FSK is given by :
2Δf + 2B, where B is the bit rate.
7.
8. Multiple FSK ( MFSK) :
MFSK is a variation of FSK that uses more than 2 frequencies.
MFSK is a form of M-ary orthogonal modulation. MFSK is classed as an M-ary orthogonal
signaling scheme because each of the M tone detection filters at the receiver responds only
to its tone and not at all to the others; this independence provides the orthogonality.
M, the size of alphabet, is usually a power of 2 , so that, each symbol represent log2M bits.
The required Eb/N0 ratio (energy per bit to noise power spectral density ratio ) for a given
probability of error decreases as M increases.
Eb/N0
It’s useful when comparing the bit error rate (BER) performance of different digital
modulation schemes without taking bandwidth into account.
Eb/N0 is closely related to the carrier- to- noise ratio (CNR or C/N), i.e. the signal-to-noise-
ratio (SNR) of the received signal, after the receiver filter but before detection:
9. where
fb is the channel data rate
B is the channel bandwidth
As M approaches infinity the required Eb/N0 ratio decreases asymptotically to
the Shannon limit of -1.6 dB.
10. Audio FSK (AFSK) and it’s applications :
AFSK is a modulation technique by which digital data is represented by changes
in the frequency of an audio tone, yielding an encoded signal suitable for
transmission via radio or telephone.
Normally, the transmitted audio alternates between two tones: one, the "mark",
represents a binary one; the other, the "space", represents a binary zero.
Most early telephone-line modems used audio frequency-shift keying (AFSK) to
send and receive data at rates up to about 1200 bits per second.
Some early microcomputers used a specific form of AFSK modulation, the
Kansas City Standard(Byte standard), to store data on audio cossets.
AFSK is not always used for high-speed data communications, since it is far less
efficient both power and bandwidth than most other modulation modes.
11. • Phase-shift keying (PSK) is a method of digital communication in which
the phase of a transmitted signal is varied to transmit information. There are
several methods that can be used to do PSK.
Phase Shift Keying
•The simplest PSK technique is called binary phase-shift keying (BPSK). It uses two
opposite signal phases (0 and 180 degrees). The digital signal is broken up timewise
into individual bits (binary digits).
15. The “PSK” in 8PSK refers to the use of Phased Shift Keying.
Phased Shift Keying : is a form of phase modulation which is
accomplished by the use of a discrete number of states. 8PSK
refers to PSK with 8 sates.
With half that number of states, you will have QPSK. With
twice the number of states as 8PSK, you will have 16PSK
16. Differential phase shift keying is a no coherent form
of phase shift keying ; which avoids the need for a
coherent reference signal at the receiver.
No coherent receivers are easy and cheap to build, and
hence are widely used in wireless communications. In
DPSK system, the input binary sequence is first
differentially encoded and then modulated using a
BPSK modulator.
17. DPSK → COHERENT
→ NON-COHERENT
Coherent systems need carrier phase information at
the receiver and they use matched filters (or
correlation receiver) to detect and decide what data
was sent
while non coherent systems do not need carrier
phase information and use methods like square law
(push detection or energy detection) to recover the
data.
18. coherent vs noncoherent
In terms of performance coherent systems are much
better than non coherent systems.
DPSK: non-coherent
QPSK & BPSK & MPSK : coherent
In coherent phase shift keying different phase
modulation schemes will be covered i.e. binary PSK,
quadrature phase shift keying and M-ary PSK
19. OFF-SET PSK
At 180 phase-shift, the amplitude of the transmitted
signal changes very rapidly costing amplitude change .
This signal may be distorted when is passed through
the filter or nonlinear amplifier.
To solve the amplitude change problem, we propose
the offset QPSK.
Offset QPSK delay the data in quadrature component
by T/2 seconds (half of symbol).
In the offset QPSK, the phase of the signal can change
by 90 or 0 degree only ,,, while in the QPSK the phase
of the signal can change by 180; 90 or 0 degree.
21. A wireless local area network (WLAN) links two or
more devices using some wireless distribution
method ,and usually providing a connection through
an access point to the wider Internet. This gives users
the mobility to move around within a local coverage
area and still be connected to the network. Most
modern WLANs are based on IEEE 802.11 standards,
marketed under the Wi-Fi brand name. WLANs were
once called LAWNs (for local area wireless network)
by the Department of Defense.
22. Wireless LANs have become popular in the home due
to ease of installation, and in commercial complexes
offering wireless access to their customers; often for
free
23. How to choose ??
There are many other types of modulation you could
use and which one would work best would depend
on your project
24. Differences
FSK vs PSK
less susceptible to interference .
easier to generate with modern electronics
BFSK requires twice the bandwidth of BPSK
power fsk is better compared to psk
but
it is expensive
ASK
Simplicity
low implementation costs
conserving power.
25. How to Imagine noise ?
ф1 and ф 2 are vectors
Each diagram represents the additive noise with a dashed
line circle around the signal.
26. FSK vs PSK noise immunity?
you need to define a quantitative metric that has a level playing
field between the two, such as measuring the systems' bit-error
rate versus the signal to noise ratio ”