This chapter discusses noise in communication systems. It defines noise and describes different types of noise including correlated and uncorrelated noise. Key noise parameters like signal-to-noise ratio, noise figure, and noise factor are analyzed. The chapter also examines how noise affects angle modulation and how preemphasis and deemphasis networks can be used to improve the signal-to-noise ratio in frequency modulation systems by boosting the high frequency signal components during transmission and restoring the original amplitude profile during reception.
Study of Planar Inverted - F Antenna (PIFA) for mobile devices Naveen Kumar
A brief study of planar inverted-F antenna is given. Basic structure of PIFA is discussed and effect of various parameters is explained. Techniques to improve bandwidth coverage by the antenna are also discussed.
Study of Planar Inverted - F Antenna (PIFA) for mobile devices Naveen Kumar
A brief study of planar inverted-F antenna is given. Basic structure of PIFA is discussed and effect of various parameters is explained. Techniques to improve bandwidth coverage by the antenna are also discussed.
Sensitivity or selectivity - How does eLNA impact the receriver performancecriterion123
it describes
1. Why need external LNA ?
2. Why does poor linearity lead to poor sensitivity ?
3. For the eLNA gain, the more the better ?
4. Why can SAW filter improve linearity ?
Sampling Theorem, Quantization Noise and its types, PCM, Channel Capacity, Ny...Waqas Afzal
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This thesis focuses on mobile phones antenna design with brief description about the historical development, basic parameters and the types of antennas which are used in mobile phones. Mobile phones antenna design section consists of two proposed PIFA antennas. The first design concerns a single band antenna with resonant frequency at GPS frequency (1.575GHz). The first model is designed with main consideration that is to have the lower possible PIFA single band dimensions with reasonable return loss (S11) and the efficiencies. Second design concerns in a wideband PIFA antenna which cover the range from 1800MHz to 2600MHz. This range covers certain important bands: GSM (1800MHz & 1900MHz), UMTS (2100MHz), Bluetooth & Wi-Fi (2.4GHz) and LTE system (2.3GHz, 2.5GHz, and 2.6GHz). The wideband PIFA design is achieved by using slotted ground plane technique. The simulations for both models are performed in COMSOL Multiphysics.
The last two parts of the thesis present the problems of mobile phones antenna. Starting with Specific absorption rate (SAR) problem, efficiency of Mobile phones antenna, and hand-held environment.
Sensitivity or selectivity - How does eLNA impact the receriver performancecriterion123
it describes
1. Why need external LNA ?
2. Why does poor linearity lead to poor sensitivity ?
3. For the eLNA gain, the more the better ?
4. Why can SAW filter improve linearity ?
Sampling Theorem, Quantization Noise and its types, PCM, Channel Capacity, Ny...Waqas Afzal
Sampling Theorem
Quantization
Noise and its types
Encoding-PCM
Power of Signal
Signal to noise Ratio
Channel Capacity
Nyquist Bandwidth
Shannon Capacity Formula
Multirate Digital Signal Processing-Up/Down Sampling
Applications
This thesis focuses on mobile phones antenna design with brief description about the historical development, basic parameters and the types of antennas which are used in mobile phones. Mobile phones antenna design section consists of two proposed PIFA antennas. The first design concerns a single band antenna with resonant frequency at GPS frequency (1.575GHz). The first model is designed with main consideration that is to have the lower possible PIFA single band dimensions with reasonable return loss (S11) and the efficiencies. Second design concerns in a wideband PIFA antenna which cover the range from 1800MHz to 2600MHz. This range covers certain important bands: GSM (1800MHz & 1900MHz), UMTS (2100MHz), Bluetooth & Wi-Fi (2.4GHz) and LTE system (2.3GHz, 2.5GHz, and 2.6GHz). The wideband PIFA design is achieved by using slotted ground plane technique. The simulations for both models are performed in COMSOL Multiphysics.
The last two parts of the thesis present the problems of mobile phones antenna. Starting with Specific absorption rate (SAR) problem, efficiency of Mobile phones antenna, and hand-held environment.
different types of internal and external noises, s/n ratio, s/n ratio of a tandem connection, noise factor, amplifier input noise, noise factor of amplifiers in cascade (friss's formula).
System(board level) noise figure analysis and optimizationcriterion123
For sensitivity, what a system (board level) RF engineer can improve is only noise figure. This document describes that the noise figure concept you should know, and how to optimize it to improve sensitivity.
The signal is the meaningful information that you’re actually trying to detect. The noise is the random, unwanted variation or fluctuation that interferes with the signal. To get a sense of this, imagine trying to tune into a radio station. Ok, you don’t use radio anymore, so imagine your dad can’t call you to get help setting up his Spotify, so is trying to tune into a radio station. He turns the dial but it’s just picking up white noise and, after a few frustrating minutes, he manages to pick up a signal and tune into a station.
The same is true in statistics — there is something you’re trying to actually measure (say, how many Americans want to leave for Canada), but the data could be noisy (by including everyone who just makes a trip over the border to buy affordable medication). Noisy data are data from which it is hard to determine the true effect.Examples of signal vs noise
If I speak German, for most people, there will be no signal, just noise, although Claus can detect the actual signal.
How accurate are the polls in predicting the election? If the data are noisy (for example, because it’s a small sample size, has low external validity, or small effect size), the poll numbers won’t correlate well with a change in the chance of a different President.
Does money make you happier? The signal (correlation between income and happiness) would be noisy because of confounders — you’d expect people who earn more to be happier because they are in positions of higher social status, they have better working conditions, being happier could cause people to be rich etc. Turns out there is some signal amongst the noise though.
RF testing has remained hype for most of us. But seriously it is not so. It can be very interesting and one can develop a lot of interest in this if given an opportunity.
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We have also described the basic principles of Signal Analyzer and Signal Generator which are the most common test tools used for any radio testing.
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Most meaningful criteria for measuring performance of a digital communication system is average error probability, and in analog system, it is peak signal to rms noise ratio. ...
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Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
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Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Thesis Statement for students diagnonsed withADHD.ppt
Chapter 5 noise
1. Chapter 5: Noise 82
Chapter 5: Noise
Learning Outcomes
At the end of this chapter, the student should be able to:
1. Explain and differentiate several types or sources of noise available in
communication system.
2. Analyse the noise parameters such as signal-to-noise ratio, noise figure and noise
factor.
3. Explain and analyse the communication system performances in the presence of
noise.
4. Describe the use of preemphasis and deemphasis network in improving the signal-
to-noise ratio of communication signal.
BENT 3113: Communication Principles
2. Chapter 5: Noise 83
Chapter 5: Noise
5.1 Noise – Representation, Types and Sources
Electrical noise is defined as any undesirable electrical energy that falls within the passband
of the signal.
Figure 5.1 shows the effect that noise has on the electrical signal:
Figure 5.1: Effects of noise on a signal: (a) without noise; (b) with noise
Noise can be divided into two general categories: correlated and uncorrelated. Correlation
implies a relationship between the signal and the noise. Therefore, correlated noise exists
only when a signal is present. Uncorrelated noise is present all the time whether there is a
signal or not
5.1.1 Uncorrelated Noise
Uncorrelated noise can be further subdivided into two general categories: external and
internal
External noise (generated outside the device or circuit)
a. Atmospheric noise
• Naturally occurring electrical disturbances that originate within Earth’s atmosphere
such as lightning
• Also known as static electricity
b. Extraterrestrial noise
• Consists of electrical signals that originate from outside Earth’s atmosphere and
therefore also known as deep-space noise
• Subdivided into two categories
o Solar noise that is generated directly from the sun’s heat
o Cosmic noise/black-body noise that is distributed throughout the galaxies
BENT 3113: Communication Principles
3. Chapter 5: Noise 84
c. Man-made noise
• Noise that is produced by mankind
• The predominant sources of this noise are spark-producing mechanism, such as
commutators in electric motors, automobile ignition systems, ac power-generating
and switching equipment and fluorescent lights
• Sometimes known as industrial noise
Internal noise (generated within a device or circuit)
a. Shot noise
• Caused by the random arrival of carriers (holes and electrons) at the output element of
an electronic device
• Shot noise is randomly varying and is superimposed onto any signal present
b. Transit-time noise
• Irregular, random variation due to any modification to a stream of carriers as they
pass from the input to the output of a device
• This noise become noticeable when the time delay takes for a carrier to propagate
through a device is excessive
c. Thermal/random noise
• Associated with the rapid and random movement of electrons within a conductor due
to thermal agitation
• Also known as Brownian noise, Johnson noise and white noise
• Uniformly distributed across the entire electromagnetic spectrum
• A form of additive noise, meaning that it cannot be eliminated, and it increases in
intensity with the number of devices and with circuit length
• The most significant of all noise sources
• Thermal noise power
N = KTB (5.1)
N = noise power (watts), B = bandwidth (hertz), T = absolute temperature (kelvin)
K = Boltzmann’s constant ( 1.38 × 10 −23 joules/kelvin)
Note: T = 0 C + 273 0
The following figure shows the equivalent circuit for a thermal noise source when the internal
resistance of the source RI is in series with the rms noise voltage V N
BENT 3113: Communication Principles
4. Chapter 5: Noise 85
Figure 5.2: Noise source equivalent circuit
For worst-case condition and maximum transfer of noise power, the load resistance R is made
equal to internal resistance. Thus the noise power developed across the load resistor:
(V / 2) 2 V N2
N = KTB = N =
R 4R
Thus V N = 4 RKTB (5.2)
5.1.2 Correlated Noise
Correlated noise is a form of internal noise that is correlated to the signal and cannot be
present in a circuit unless there is a signal. It is produced by nonlinear amplification resulting
in nonlinear distortion. There are two types of nonlinear distortion that create unwanted
frequencies that interfere with the signal and degrade performance:
a. Harmonic distortion
• Occurs when unwanted harmonics of a signal are produced through nonlinear
amplification
• Harmonics are integer multiples of the original signal. The original signal is the first
harmonic (fundamental frequency). A frequency two times the fundamental frequency
is the second harmonic, three times is the third harmonic, and so on
• Distortion measurements
o Nth harmonic distortion = ratio of the rms amplitude of Nth harmonic to the
rms amplitude of the fundamental
o Total harmonic distortion (THD)
v higher
% THD = × 100 (5.3)
v fundamental
2 2 2 2
Notes: v higher = v 2 + v3 + v 4 + ..... + v n and all in rms values
BENT 3113: Communication Principles
5. Chapter 5: Noise 86
b. Intermodulation distortion
• Intermodulation distortion is the generation of unwanted sum and difference
frequencies produced when two or more signal mix in a nonlinear device (called cross
products)
• The emphasis here is on the word unwanted because in communication circuits it is
often desirable to produce harmonics or to mix two or more signals to produce sum
and difference frequencies
Figure 5.3 shows both forms of correlated noise
Figure 5.3: Correlated noise: (a) Harmonic distortion; (b) Intermodulation distortion
5.1.3 Other Noise Types
a. Impulse noise
• Characterized by high-amplitude peaks of short duration (sudden burst of irregularly
shaped pulses) in the total noise spectrum
• Common sources of impulse noise: transients produced from electromechanical
switches (relays and solenoids), electric motors, appliances, electric lights, power
lines, poor-quality solder joints and lightning
b. Interference
• Electrical interference occurs when information signals from one source produce
frequencies that fall outside their allocated bandwidth and interfere with information
signals from another source
• Most occurs in the radio-frequency spectrum
BENT 3113: Communication Principles
6. Chapter 5: Noise 87
5.2 Noise Parameters
5.2.1 Signal-to-Noise Power Ratio
Signal-to-noise power ratio (S/N) is the ratio of the signal power level to the noise power
level and can be expressed as
S Ps
= (5.4)
N Pn
S P
In logarithmic function (dB) = 10 log s (5.5)
N Pn
It can also be expressed in terms of voltages and resistance
S Vs2 / Rin
(dB) = 10 log 2
V / R
(5.6)
N n out
If the input and output resistances are equal, Equation (5.6) can be reduced to
S V
(dB ) = 20 log s (5.7)
N Vn
5.2.2 Noise Factor and Noise Figure
Noise factor is the ratio of input signal-to noise ratio to output signal-to-noise ratio
( S / N ) in
F= (5.8)
( S / N ) out
Noise figure is the noise factor stated in dB and is a parameter to indicate the quality of a
receiver
( S / N ) in
NF = 10 log F = 10 log
(S / N )
(5.9)
out
Noise Figure in Ideal and Nonideal Amplifiers
An electronic circuit amplifies signals and noise within its passband equally well. Therefore,
if the amplifier is ideal and noiseless, the input signal and noise are amplified the same and
the signal-to-noise ratio at the output will equal the signal-to-noise ratio at the input. In
reality, amplifiers are not ideal. Therefore, the amplifier adds internally generated noise to the
waveform, reducing the overall signal-to-noise ratio
The figure on the next page shows the noise figure for both ideal and nonideal amplifier.
BENT 3113: Communication Principles
7. Chapter 5: Noise 88
Figure 5.4: Noise figure: (a) ideal, noiseless amplifier; (b) nonideal amplifier
• For Figure 5.4 (a), the input and output S/N ratios are equal
• For Figure 5.4 (b), the circuit adds the internally generated noise N d to the waveform.
Consequently, the output signal-to-noise ratio is less than the ratio at the input
Noise Figure in Cascaded Amplifiers
When two or more amplifiers are cascaded as shown below, the total noise factor is the
accumulation of the individual noise factors.
• Friiss’ formula is use to calculate total noise factor of several cascaded amplifiers
F2 − 1 F3 − 1 FN − 1
FT = F1 + + + ... + (5.10)
A1 A1 A2 A1 A2 ... AN
• The total noise figure
NFT = 10 log FT (5.11)
Figure 5.5: Noise figure of cascaded amplifiers
Note: To use Friiss’ formula, the noise figures must be converted to noise factors
5.3 Noise and Angle Modulation
When thermal noise with constant spectral density is added to an angle-modulated signal, it
produces an unwanted deviation of the carrier frequency. The magnitude of this deviation
BENT 3113: Communication Principles
8. Chapter 5: Noise 89
depends on the relative amplitude of the noise with respect to the carrier. Consider one
interfering noise signal with amplitude Vn and frequency f n
• For PM, the unwanted peak phase deviation due to this interfering noise signal is
given by
V
∆θ peak ≈ n rad (5.12)
Vc
• For FM, when Vc > Vn , the unwanted instantaneous phase deviation is approximately
V
θ (t ) = n sin(ω n t + θ n ) rad (5.13)
Vc
Taking derivative, we obtain
V
∆ω (t ) = n ω n cos(ω n t + θ n ) rad/s
Vc
Therefore, the unwanted peak frequency deviation is
Vn Vn
∆ω peak = ω n rad/s, ∆f peak = f n Hz (5.14)
Vc Vc
When this unwanted carrier deviation is demodulated, it becomes noise.
• The frequency of the demodulated noise signal is equal to the difference between the
carrier frequency and the interfering signal frequency ( f c − f n )
• The signal-to-noise ratio at the output demodulator due to unwanted frequency
deviation from an interfering signal is the ratio of the peak frequency deviation due to
the information signal to the peak frequency deviation due to the interfering signal
S ∆ f signal
= (5.15)
N ∆ f noise
The spectral shape of the demodulated noise depends on whether an FM or a PM
demodulator is used as shown in Figure 5.6
• The noise voltage at the output of PM demodulator is constant with frequency
• The noise voltage at the output of FM demodulator increases linearly with frequency
BENT 3113: Communication Principles
9. Chapter 5: Noise 90
Figure 5.6: FM and PM noise
5.4 Preemphasis and Deemphasis
From Figure 5.6, there is nonuniform distribution of noise in FM. Noise at the higher-
modulating signal frequency is greater than noise at lower frequencies. Therefore, for
information signal with a uniform signal level, a nonuniform signal-to-noise ratio is produced
as shown below
Figure 5.7: FM signal-to-noise ratio: (a) without preemphasis; (b) with preemphasis
• S/N ratio is lower at the high-frequency ends of the triangle (Figure 5.7 (a))
• To compensate for this, the high-frequency modulating signals are emphasized or
boosted in amplitude prior to performing modulation (Figure 5.7 (b))
• At the receiver, to compensate this boost, the high frequency signals are
deemphasized or attenuated after the demodulation is performed
In essence, the preemphasis network allows the high-frequency modulating signal to
modulate the carrier at a higher level while the deemphasis network restores the original
amplitude-versus-frequency characteristics to the information signals
• A preemphasis network is a high pass filter (i.e. a differentiator)
• A deemphasis network is a low pass filter (i.e. a integrator)
The following figure shows the schematic diagrams for preemphasis and deemphasis and
their corresponding frequency response curves
BENT 3113: Communication Principles
10. Chapter 5: Noise 91
Figure 5.8: Preemphasis and deemphasis: (a) schematic diagrams, (b) frequency-response
• The break frequency (the frequency where pre- and deemphasis begins) is determined
by the RC or L/R time constant of the network
1 1
fb = = (5.16)
2πRC 2πL / R
• The networks shown are for the FM broadcast band, which uses a 75-µs time
constant. Therefore the break frequency is approximately 2.12 kHz
From the preceding explanation and Figure 5.8, it can be seen that the output amplitude from
a preemphasis network increases with frequency for frequencies above break frequency
• From Equation (4.13), if changes in f m produce corresponding changes in Vm , the
modulation index m remains constant
o This is the characteristic of phase modulation (modulation index independent
of frequency)
o I.e. for frequencies below 2.12 kHz produces FM, and frequencies above 2.12
kHz produce PM
BENT 3113: Communication Principles