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Friday, September 28, 2018

Reflector Antenna

September 28, 2018 0

Reflector antenna:
-reflectors are widely used to modify the radiation patterns of a radiating element.
Microwave antenna:
UHF and SHF bands are resp. 300-3000MHz, and 3000-30000MHz but the microwave region extends from 1GHz to 100 GHz. The transmitting and receiving antennas in microwave frequencies are directive with high gain and narrow BW in both horizontal and vertical planes.
-As the frequencies increases, the wavelength decreases and thus it becomes easier to construct and antenna system that are large in terms of wavelength and which therefore can be made to have greater directivity.
Types of reflectors:
(i). Rod reflector:
-mainly used in yagi-antenna
-placed behind the driven elements
- L = λ/2
- it offers inductive reactance and contributes in increasing the gain
-main disadvantage is: it alters impedance of driven element
(ii). phase reflector:
 -simplest reflector to direct electromagnetic energy in desired direction
-But it is difficult to collimate the energy in forward direction

Fig: phase reflector

-In fact polarization of the primary antenna and its position with respect to the reflecting surface is used to control the pattern characteristics, impedances, power gain, and directivity of complete system
(iii). Corner reflector:  
-is a reflecting object, which consists of two or three, mutually intersecting, conducting flatter surfaces
-Dihedral forms of corner reflector are frequently used in antenna
-Trihedral forms with mutually perpendicular surfaces are used as radar targets

Where,
d = aperture size, l = length
d1 = spacing between vertex and feed point location
α – angle (inclined angle)
-A corner reflector is designed to improve the collimation of electromagnetic energy in the forward direction and to eliminate radiation in back and side direction
Features:
(a). most preferred value of α = 90°
(b). d1 is increased if α is decreased and vice-versa in order to improve efficiency
(c). when α is small, gain is increased by increasing the length of sides of reflector
(d). used as passive target for radar and communication application to return the signal exactly in same direction by choosing α = 90°
-due to this unique feature, most of defense-ships and vehicles are designed with minimum sharp corners to reduce the chances of their detection by enemies’ radars.
-also used in home television antennas

# Parabolic Reflector:
-It is the reflector antenna, which has the shape of paraboloid and employs the properties of parabola



Fig: Different types of parabolic feeder

-parabolic reflectors are  based on the geometric optical principles
-A parabola may be defined as the locus of a point, which moves in such a way that it’s distance from the fixed point called focus plus its distance from a straight line called directrix is constant
                                                 Fig: Geometry of parabolic reflector

The parabola is a two-direction plane curve
OF=Focal length = f

O = Vertex
F = Focus
 OO´ = Axis of parabola
 AB = directrix
By the definition of parabola, we have
FP + PP´ = FQ + QQ´ = FS + SS´ = constant (K)
Where K = a constant depends on the shape of parabola curve
The eqn of parabola is
 y2 = 4 fx
-the open mouth (D) of parabola is known as Aperture
-the ration of focal length to aperture size
i.e. . (f/D) known as ‘f over D ratio’ is an important characteristic of parabolic reflector and its value usually varies between 0.25 to 0.50
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Thursday, September 27, 2018

Primary Storage

September 27, 2018 0
Essential stockpiling is described by quicker access time, less capacity limit and higher expenses when contrasted with auxiliary stockpiling units. Essential stockpiling or fundamental memory is that piece of the PC framework which stores the projects, information and middle of the road results amid the program execution. An essential stockpiling comes as a fundamental piece of all PC frameworks. It involves various little areas. Every area has an interesting number appointed to it. This is called as the location of the area and it is utilized to distinguish the area. Every area has an ability to store a settled number of bits. The quantity of bits that an area can store is called as word length. Every area contains a similar number of bits. Ordinarily, essential memory measure ranges from a couple of kilobytes on little PCs to a few thousand kilo bytes and megabytes on bigger machines. 

The essential stockpiling is unstable. At whatever point the power is killed the information is lost. Essential stockpiling is additionally called Random Access Memory (RAM). Smash implies it is conceivable to haphazardly choose and utilize any capacity area for capacity and recovery of information. Slam is additionally called a perused/compose memory since information can both be perused from and composed onto these units. At the point when the power is turned off the information put away in the RAM is lost.





  • ROM: ROM is Read Only Memory. In this kind of memory the information is for all time put away. The data must be perused and new information can't be composed onto this memory. Anyway the substance of the ROM are not lost notwithstanding when the power is killed i.e. this memory is non-unstable. Such recollections are additionally called as field stores, or changeless stores. There are various abnormal state capacities which are required to be performed by the PC framework. Such capacities are performed by composing exceptional projects called small scale programs. Miniaturized scale programs by and large execute the low level machine capacities. These projects are basically utilized as a substitute for equipment. Such projects can be put away on ROMs and be utilized over and over. This outcomes in decreasing the equipment of the framework. ROM expands the proficiency of the CPU as it can perform specific errands. ROM comes as a chip. When data is put away on a ROM chip it can't be changed or modified.
  • PROM: PROM is Programmable Read Only Memory. These are ROMs which can be customized. An uncommon PROM software engineer is utilized to enter the program on the PROM. Once the chip has been modified, data on the PROM can't be adjusted. PROM is non - unstable i.e. information isn't lost when control is turned off.
  • EPROM: Another kind of memory is the Erasable Programmable Read Only Memory. It is conceivable to delete the information which has been already put away on an EPROM and compose new information onto the chip. • Cache Memory: This is an extremely extraordinary kind of rapid memory. This memory can't be gotten to by the client. The fundamental capacity of this store memory is to make the projects and information accessible to the CPU quick. Access time of memory is by and large high when contrasted with the execution time of the GPU. Thusly a reserve, which is a little however quick memory, is utilized between the CPU and the principle memory. This memory likewise called a rapid cushion. A reserve stores those portions of projects and information which are often required. It makes accessible this information to the CPU at a quick rate along these lines expanding the proficiency.
  • Registers: Registers are utilized to hold data incidentally. These are unique memory units which are not real parts of the principle memory, but rather permit proficient development of data between the different units of the PC framework. The registers get data, hold it incidentally and make it accessible as and when required. A PC utilizes various registers, where each enlist plays out a particular capacity. A portion of the normal registers are: 

1. Memory Address Register (MAR): The capacity of this enlist is to hold the location of the present or dynamic memory area. 

2. Memory Buffer Register (MBR): This enlist holds the substance of the location from which information is perused or to which information has been composed. 

3. Program Control Register: It holds the location of the following guidance to be executed. Aggregator Register: It holds the underlying information, the moderate outcomes and the last information of the program under execution. 

4. Instruction Register: This enroll holds the present guidance being executed. Information/yield Register: The capacity of this enroll is to speak with the Input/yield gadgets. 

The capacity limit of essential stockpiling is restricted. It is typically not adequate to suit every one of the information. Thusly optional capacity medium is utilized to store substantial volumes of information. The expense of auxiliary memory is substantially less when contrasted with essential memory. Nonetheless, get to time of essential memory is quick. The information put away on optional capacity is exchanged to the essential stockpiling as and when required. Optional capacity is additionally called helper memory. Auxiliary stockpiling is utilized for putting away duplicates of information and projects. This is a non-unstable memory and is put away outer to the PC.
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Saturday, September 8, 2018

Filter

September 08, 2018 0
Filter can be considered can be considered as recurrence specific systems. A channel is required to isolate an undesirable flag from a blend of needed and undesirable signs. The channel determination are by and large given as far as cutoff frequencies, pass band (P.B) and stop band (s.b) districts. P. B is the recurrence band of needed flag and S.B is the recurrence band of undesirable flag. A perfect channel should pass the needed flag with no lessening and give endless weakening. Contingent on the segments utilized, channels can be delegated: 1. latent channels: Filters which are the compotnet, for example, R,L,C are the uninvolved channels. The Gains of such channels are in every case not exactly or equivalent to solidarity (i.e GS1). It is to be noticed the L and C are channel parts, yet R isn't. 2. Dynamic channels: The channels which utilize the parts, for example, transistors, operation amp and so forth are the dynamic channels. The Gains of such channels are constantly more prominent than or equivalent to solidarity. ( G ≥ 1)

Gain and Attenuation:   


Let us consider the filters network with i/p V1(t)  having power P1 and o/p V2(t) having power p2 as shown in fig1. Then the transfer function is given by T(s) = V2(s)/V1(s) Where , V1(s) and V2(s) are the Laplace Transform of V1(t) . 





Then the voltage gain in db is given by ,  Av = 20log10 |T(jw )|  dB …………….(1) 
Or in term of power , the power gain is given by,  




Now, the voltage attenuation is given by ,  α = 1/Av    α = -20log|T(jw )| dB…………….(2) 
From equation 1 and 2 ,we can write,  






Types of filters: ( According to the function)   

Filters are classified according to the functions they are to perform. The pattern of PB and SB that give rise to the most common filters as defined below:

1. Low pass filters: (LPF):  A LPF characteristics is one in which the PB extend from ω = 0 to ω = ωc where ωc is know as cut off frequency. 











2. High pass filter:  A  high pass filter is a complement of a low pass filter in that the frequency range form o to ωc is the SB and from ωc to infinity  is the PB. 










3. Band pass filter ( BPF):  A BPF is one in which the frequency extending form ωL (or ω1) to ωu (ω2 ) are passed while signals at all other frequencies are stopped. 




4. Band stop filter(BSF):  A BSF is complement of BPF where signal components at frequencies form ω1 to ω2 are stopped and all others are passed. These filters are sometimes known as “Notch filters”. 


5. All pass filters (APF): It is a filter which passes all range of frequencies , i.e , PB ranges from o to infinity. 









Non- ideal Characteristics: 

         Filter                          Gain curve                                      Attenuation curve 





 1. From the attenuation curve it to be noted that in the pass band the attenuation is always less then a maximum value. Designated as αmax
2. In the stop band the attenuation is always larger then a minimum value designated as α min .
3. Band between PB and SB so defined are known as transition bands. (TB). 
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Introduction and Development of Microprocessor

September 08, 2018 0
Introduction:

- If ALU, CU and registers are incorporated on a solitary chip utilizing LSI or VLSI at that point, coming about processor is called microchip unit or essentially chip.

- A clock driven semiconductor gadget comprising of electronic rationale circuits produced by utilizing either LSI or VLSI strategies.

- A multipurpose, programmable, clock-driven enlist based electronic gadget that peruses double information as information and process information as indicated by given guideline and gives results as yield.


Development/ Evolution of Microprocessor:

Evolution of Some Intel Processors:
8080:
-First general purpose microprocessor
-8 bit machine with 8 bit data and 16 bit address path to memory
8086:
-Powerful 16 bit machine with 1MB memory capacity
- have wider data path, larger registers and pipelining
-consist of instruction cache
80286:
-8086 with addressing capacity 16MB instead of 1MB
80386:
- Intel’s first 32 bit microprocessor
-complex and power of mini computers and mainframes
80486:
-uses sophisticated, more powerful cache technology and pipelining
Pentium:
-introduces the use of super scalar techniques
-allow multiple instructions to execute in parallel




→Small computer that contains microprocessor is called microcomputer.
→They ranges from 4 -bit word to 32 – bit words.
→ CPU is single integrated circuit called microprocessor.    
→ Major parts are central processing unit, memory, input/ output ports.
→Each of these parts are connected through address bus, data bus and control bus.

Von-Neumann Machine:

- program for the ENIAC was to a great degree dull 

- The programming procedure could be encouraged if the program could be spoken to in a shape reasonable for putting away in memory close by the information 

- Then, a PC could get its guidelines by understanding them from the memory and a program could be set or adjusted by setting the estimations of a bit of memory. This approach is called STORED PROGRAM CONCEPT, first adjusted by John Von Neumann 

- The Von Neumann Architecture is the essential reason for the design of the present advanced PCs.





- The Von Neumann engineering is a plan show for put away program computerized PC that uses a focal preparing unit (CPU) and a solitary separate stockpiling structure (memory) to hold the two directions and information 

- The Arithmetic Logic Unit (ALU) is equipped for performing math and legitimate tasks on paired information 

- control unit interferes with the directions in memory and cases them to be executed 

- The I/O unit gets worked from the control unit 

- The capacity area of the CU and ALU are called REGISTERS.


The Various Registers of this model are:

(i). MBR (Memory Buffer Register)
(ii). MAR (Memory Address Register)
(iii). IR (Instruction Register)
(iv). IBR (Instruction Buffer Register)
(v). PC (Program Counter)


Harvard Architecture:
- In Von Neumann design, the handling pace of PC is moderate. The Harvard design based PC comprises of particular memory spaces for guidelines and memory. Every memory space has its own particular address and information transport 





- The program memory information transport and information memory information transport are multiplexed to shape single information transport and same for address transport 

- Two timekeepers of RAM chips are for program memory and another for information memory 

- Both guidelines and information can be brought from memory simultaneously (increment in speed) 

- The information memory address: number juggling unit creates information memory address 

- Data memory address transport conveys the memory address of the information. While, program memory address transport conveys the memory address of the guideline 

- Central math unit comprises of ALU, multiplier, Ac (collector) 

- PC is utilized to address program memory 

- Control unit controls the grouping of activity to be executed


Fig: Harvard Architecture
                      Source: TU IOE Microprocessor Manual (EG573EX), Oct. 1999, Pg.:6


Application of Microprocessor


In this growing electronics world none of the sector will be away from the use of microprocessor. However, its applications of Microprocessor are generalized in following groups:
(i). Test instruments
(ii). Communications
(iii). Computer
(iv). Industries 
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Introduction to C Programing

September 08, 2018 0
C is a universally useful, organized programming dialect. Its guidelines comprises of terms that look like arithmetical articulation, enlarged by certain English watchwords, for example, if, else, for, do and keeping in mind that, and so forth. C contains extra highlights that enable it to be utilized at a lower level, in this manner crossing over any barrier between machine dialect and the more regular abnormal state dialect. This adaptability enables C to be utilized for framework programming (e.g. for composing working frameworks and in addition for applications programming, for example, for composing a program to fathom numerical condition or for composing a program to charge clients). It additionally takes after other abnormal state structure programming dialect, for example, Pascal and Fortran.

Historical Development of C:   

C was an offspring of the ‘Basic Combined Programming Language’ (BCPL) called B, developed in 1960s at Cambridge University. B language was modified by Dennis Ritchie and was implemented at Bell Laboratories in 1972. The new language was named C. Since it was developed along with the UNIX operating system, it is strongly associated with UNIX. This operating system was developed at Bell Laboratories and was coded almost entirely in C. 
 C was used mainly in academic environments for many years, but eventually with the release of C compiler for commercial use and the increasing popularity of UNIX, it began to gain populuidespread support among compiler professionals. Today, C is running under a number of operating systems including Ms-DOA. C was now standardized by American National Standard Institute. Such type of C was named ANSI C.

 Importance of C: 
Presently a-days, the fame of C is expanding most likely because of its numerous alluring characteristics. It is a vigorous dialect whose rich arrangement of implicit capacities and administrators can be utilized of worked in capacities and administrators can be utilized to compose any perplexing project. The C compiler joins the abilities of a collect dialect with the highlights of an abnormal state dialect and in this way it appropriate for composing both framework programming and business bundles. Truth be told, huge numbers of the C compilers accessible in the market are composed in C. 



Projects written in C are effective and quick. This is because of its assortment of information composes and great administrators. It is commonly quicker than BASIC (Beginners All Purpose Symbolic Instruction Code – an abnormal state programming dialect). 

There are just 32 watchwords and its quality lies in its implicit capacities. A few standard capacities are accessible which can be utilized for creating programs. C is exceedingly convenient. This implies C programs composed for one PC can be seen on another with next to zero alteration. Transportability is vital in the event that we intend to utilize another PC with an alternate working framework. 

C Language is appropriate for structure programming hence requiring the client to think about an issue as far as capacity modules or squares. A legitimate gathering of these modules would make an entire program. This secluded structure makes program investigating, testing and upkeep. 

Another imperative component of C is its capacity to expand itself. A C program is essentially an accumulation of capacities that are bolstered by the C library. We can consistently add our own capacity to the C library. With the accessibility of an extensive number of capacities, the programming errand ends up straightforward.


Basic Structure of C programs: 

Each C program comprises at least one modules called work. One of the capacity must be called fundamental( ).A capacity is a sub-schedule that may incorporate at least one explanations intended to play out a particular assignment. A C program may contain at least one areas appeared in fig: 




The documentation area comprises of an arrangement of remark lines giving the name of the program, the creator and different subtle elements which the developer might want to utilize later. The connection area gives guidelines to the compiler to interface work from the framework library. The definition characterizes all the emblematic constants. There are a few factors that are utilized in excess of one capacity. Such factors are called worldwide factors and are announced in worldwide statement area that is outside of all the capacity. 

Each C program must have one principle( ) work area. This area comprises two sections: statement part and executable part. The announcement part proclaims every one of the factors utilized in the executable part. These two sections must show up between the opening and the end props. The program execution starts at the opening supports and closures at the end prop. The end prop of the principle ( ) work segment is the sensible end of the program. Every one of the announcements in the revelation and executable parts closes with a semicolon. 

The subprogram segment contains all the client characterized capacities that are brought in the fundamental ( ) work. Client characterized capacities are for the most part set promptly after the fundamental ( ) work, despite the fact that they may show up in any request. All area, with the exception of the primary ( ) work segment might be missing when they are not required.

Executing a C Program:

Executing a program written in C involves a series of steps:  
  1. Creating the program; 
  2. Compiling the program;
  3. Linking the program with functions that are needed from the C library; and  
  4. Executing the program

The program can be made utilizing any word handling programming in non-archive mode. The record name should end with the characters ".c" like program .c, lab1.c, and so on. At that point the charge under Ms DOS working framework would stack the program put away in the record program .c i.e. MSC pay .C and create the question code. This code is put away in another record under name 'program.obj'. In the event that any dialect mistakes are discovered , the assemblage isn't finished. The program should then be amended and accumulated once more. The connecting is finished by the summon LINK program.obj which creates the executable code with the filename program.exe. Presently the order .program would execute the program and give the outcomes.

 /* First Program written in C */ 
 /* Save it as hello.c  */  
 # include <stdio.h> /* header file */    
 main ( )  /* main ( ) function */   
{    Print (“hello, world in”), /* statement */   
}   output : hello, world  

 /* Program to calculate the area of a circle */ 
 /* area.c */   
# include <stdio.h> /* library file access */     
main( )  /* function heading */  
{       float radius, area;  /* variable decleration */     
printf (“Enter radious?=”) /* output statement */     
scanf (“%f”, & radius); /* input statement */     
area = 3.14159 * radius; /* assignment statement */     
printf (“Area=%f”, area); /* output statement */  
} 
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Sources of Errors in Digital communication systems

September 08, 2018 0
Sources of Errors in Digital communication systems:


  1.  Noise: (I) External Noise (ii) Internal Noise 
  2. Interference: (I) Inter-image impedance (ii) Inter-flag obstruction 
  3. Distortion 

1). Noise: 
Boss confinement in data transmission starting with one point then onto the next is forced by, different sorts of undesirable signs, which are normally lumped together and are called commotion.

Commotions are arbitrary and eccentric flag caused by outer or inner sources.

Classification of noise

 (I). Outer Noise: This commotion is produced outside the gadget or circuit. The three essential wellspring of outer commotion are:

i) Atmospheric

ii) Extraterrestrial

iii) Industrial (Man-made)





(i). Atmospheric Noise:

It is normally happening electrical aggravation that begins inside earth's environment. It is usually called electricity produced via friction and is the recognizable sputtering, snapping et cetera, regularly got notification from speaker when there is no flag display. The wellspring of most static electrically is normally happening electrical conditions, for example, helping, or tempest. Usually as motivations that spread vitality all through extensive variety of frequencies. The size of this vitality is conversely corresponding to its recurrence. At recurrence over 30MHz., in this way, air clamor is moderately inconsequential i.e. vast commotion is delivered in low and medium recurrence groups and little in VHF and UHF groups. 

 (ii). Extraterrestrial Noise:

It comprises of electrical signs that starts from outside earth's environment and is in this way, called profound space-clamor now and again. It begins fro, the milkyway, different universes, and the sun.

It is sub-isolated into two classifications: (a). solar (b). Cosmic

(a). solar 

It is produced straightforwardly from sun's warmth. There are two sections of sun oriented commotion: a very condition when generally consistent radiation force exists and high power: sporadic unsettling influences caused by sun spot movement and sunlight based flare-ups. The greatness of the sporadic commotion caused by sun spot movement takes after a cyclic design that rehashes like clockwork.

 (b). Cosmic:

Sources of this clamor are persistently dispersed all through the cosmic systems. Since sources are a long way from our sun, their commotion power is generally little. It is frequently called blackbody clamor and is dispersed genuinely even all through the sky.

(iii). Man-Made Noise: 

It is just clamor delivered by humanity. Principle sources are start delivering component, for example, commutator in electrical engines, vehicle start framework, air conditioning power creating and abating gear and bright light. It is imprudent in nature and contains wide recurrence go. In more thickly populated metropolitan and mechanical territory, it is in some cases called modern commotion.

(II) Internal Noise: 

It is electrical impedance created inside a gadget or circuit. There are three essential sorts of inside produced commotions:

i) shot noise

ii) Thermal noise

iii) Transit time noise

(I). Shot Noise: 

- It is caused by irregular entry of transporter (gaps and electrons) at the yield component of an electronic gadget, for example, diode, FET or BJT. It was first seen in anode current of vacuum-tube intensifier and was depicted numerically by W. schottky in 1918. The present bearers (for both air conditioning and dc) are not moving in a persistent, consistent stream in light of the fact that the separation they make a trip differs because of arbitrary way of movement. Opening clamor is arbitrarily shifting and is superimposed onto any flag show when enhanced, it sounds like metal pellets falling on a tin rooftop.
- likewise called transistor commotion and is added substance with warm clamor (noise).

(ii) Thermal Noise: 

It is related with fast and arbitrary movement of electrons inside a conductor because of warm disturbance.

The arbitrary development was first noted by English Botanist Robert Brown. Electron inside a conductor conveys a unit negative charge and the mean square speed of an electron is relative to the supreme temperature. Thus, each battle of an electron between impacts with atoms constitutes a short beat of current that grow little voltage over the resistive segment of the conductor. This sorts of electron development is absolutely irregular and toward all path, the normal voltage in substance because of this development is 0V dc. In any case, such a Radom development produces an air conditioner segment.

The air conditioner segment delivered from warm disturbance has a few names including warm commotion since it is temperature subordinate, Brownian clamor after its pioneer, Johnson clamor after the man who related Brownian molecule development of electron development and repetitive sound the irregular movement of frequencies.

Subsequently, warm commotion is arbitrary movement of free electron inside conductor caused by warm fomentation and temperature.

Scientifically,

Clamor control is:

N= KTB

Where, N = commotion control (watt)

B = Bandwidth

K = Boltzmann's consistent = 1.38*10-23J/K

T =Absolute temperature (K)

= Room temperature (27°c or 230K) (To change over °c to K include 273, i.e. T = °c + 273 K)

- Thermal commotion is irregular and consistent at all frequencies.

- Also warm commotion is unsurprising added substance and present in all gadgets. In this way, it is most noteworthy of all clamor.


(iii). Transit-Time Noise: (High frequency noise)

Any modification to a steam of carriers as they pass from input to output of a device (eg: emitter to collector of transistor) produces an irregular, random variation categorized as transit-time noise. When the time it takes for as carrier to propagate through a device is an appreciable part of the time of one cycle of signal, the noise becomes noticeable. In transistor, it is determined by carrier mobility, bias voltage, and transistor construction. Carrier travelling from emitter to collector suffers from emitter time delays, base transit-time delays and collector recombination-time and propagation –time delay. If transit delays are excessive at high frequencies, the device may add more noise than amplification to signal.


Other Internal Noises:


(i). Flicker noise (or low frequency noise): 
A component of noise appears at frequency below few KHz known as flicker noise or low frequency noise. The spectrum density of this noise increases as the frequency decreases. In vacuum tubes, it occurs due to slow changes, which takes place in oxide structure of oxide coated cathodes and migration of impurity ions through the oxide and in semiconductor due to the fluctuation in carrier density around the junction. Fluctuation in carrier density causes fluctuation in conductivity of material, which produces a fluctuating voltage drop when dc flows. This fluctuating voltage is known as flicker noise voltage.

PSD = S(ω) ∝ 1/f

(ii). Partition noise:

- happens at whatever point current need to partition between at least two ways and there is irregular vacillations in this division. Along these lines diode are less loud than transistor. 

- to stay away from parcel commotion the contributions of miniaturized scale wave collector are for the most part taken specifically to diode blends. The range of parcel clamor is level. 


Distortion:

Nature of distortion in Audio and video signal
For distortion less transmission, transfer function required is 

H(ω) = k e^(-jwtd)  
i.e. |H(ω)| = k   and

θn= -wtd



Human ear can promptly see adequacy contortion, in spite of the fact that it is heartless to stage bending. Along these lines, the producer of sound gear make accessible just |H(ω)|, the abundancy reaction normal for their framework. 

→ The human eye is touchy to stage mutilation and relative harsh to abundancy twisting. Along these lines, stage twisting on TV-video flag results in a spread picture. 

→ stage contortion is additionally essential in advanced correspondence framework on the grounds that the nonlinear stage qualities of a channel causes beat scattering (spread out), which thus makes beats meddle with neighboring heartbeats. The impedance can cause a mistake in beat sufficiency at recipient: a twofold I might be perused as 0, and the other way around. 

→ A flag transmitted over a channel is contorted as a result of different channel blemish.


(I). Linear distortion : 

Flag twisting can be caused in direct time invariant channels by no perfect attributes of either size, stage or both. This kind of bending is bothersome in TDM and FDM framework. 

(ii). Non-Linear distortion:

- caused by channel non-linearity's (i.e. in non-straight channel) 

- causes difficult issue in AM flag 

- FM flag are not influenced 

- causes genuine impedance issue in FDM frameworks (yet hot in TDM framework) 

(iii). Distortion caused by multipath effects:

- A multipath transmission happens when a transmitted flag lands at the beneficiary by at least two ways of various postponements. The multipath transmission causes non-linearity in greatness and stage normal for channel and will cause direct twisting (stage scattering)
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