Application of power transistor

This article we know that about the application of the power transistor in daily life. The transistor is a three-terminal semiconductors device as well as the current controlled device. Here we list out all the most application of the transistor to better understand this topic. A transistor is mainly used to amplify the small electrical signal and it is also useful in the amplifying circuit. So here we sort out the main application of power transistor for you.

• Used in the signal amplifier device
• Used in a digital as well as the analog circuit as a switch
• Used in power regulator and controller
• Used in Cellular phone
• Used in modern electronic IC 
• The microprocessor includes more than billion of the transistor is used in each chip
• Darlington transistor pair is often used in touch alight sensing device 
• The military also used a transistor as high power radio frequency abilities in radar and handheld  radio waves
• In daily life, we have to use a computer, radios, hearing phones which require good sound quality that needs satisfy using a transistor circuit 

Why transistor is used in daily life application?

• High voltage gain
• Require low power supply voltage for operation
• Smaller size 
• No heating problem during operation 
• Solid state device 
• Mechanically so strong
• Easily portable

Advantages and disadvantages of LCD

The Liquified Crystal Display ( LCD ) is a flat panel display, electronic visual or video display that uses the light modulating properties of liquid crystals which do not emits the light directly. LCDs are used in televisions, computer monitors the instrument panels and the aircraft cockpit displays and the signage. 

Nowadays LCDs are most commonly used in DVD players, the gaming devices, the clocks, the watches, the calculators, the telephones replaced by Cathode Ray Tube ( CRT ) in most of the applications. LCDs are available in a wider range of screen sizes compare to CRT display and a Plasma display, also they don't use phosphors, and don't suffer image burn-in. Following characteristics of LCD posses certain advantages and because of the latest innovation it also posses some disadvantages too. In this article, you can check it out the advantages and disadvantages briefly. 

Advantages of LCD :

• Slim profile
• No radiation emission from the screen
• Better under brighter conditions because of anti-glare technology
• Lighter in weight with respect to screen size
• Energy efficient because of lower power consumption 
• Brightness range is too much wider produce very bright images due to high peak intensity 
• Produce lower electric, magnetic and electromagnetic fields
• Zero geometric distortion 
• Excellent contrast 
• Low flicker rates 
• An image is perfectly sharp at the native resolution of the panel side
• Number of pixels per square inch is typically higher than any other technology or system
• Not prone to screen burn-in
• It has not affected by an increase or decrease in air pressure 

Disadvantages of LCD : 

• Slightly more expensive than CRT 
• Can't act as a portal to another dimension
• Suffer from a motion blur effect 
• High refresh rate
• Like the backlight ages, it can change colors slightly
• The aspect ratio and resolution are fixed
• Not proficient at producing black or very dark grays colors
• Restricted viewing angles 
• Slow response times 

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GPRS features

Introduction :

GPRS stands for general packet radio service. This technology allows information to be sent back and also for forth across a mobile network. It is an addition to today's circuit-switched the data and also provide short message services. This article gives advanced GPRS features to know more details about GPRS terms. 

Key features of GPRS :

• It overlays on the existing GSM network to provide high-speed data service depending on the which type of coding method is used. It is possible to have a data rate up to 150 kbps with GPRS.

• The GPRS system has the ability to offer a data speed of 14.4  kbps to 171.2 kbps that allow comfortable internet access.

• GPRS supports point to pint packet transfer service and points to multipoint packet service.

• The operator does not have to replace equipment; rather, the GPRS system is added on top of the existing infrastructure.

• GPRS based networks have a high bandwidth.

• GPRS is designed to support a bursty application like email, traffic, telemetry,  telecommunication, broadcast services, and web browsing.

• GPRS offers a fast connection set up the mechanism to offer a perception of being “always on” connection device. Hence GPRS devices are referred to as the "always connected device”.

• The security services provided by GPRS are users Authentication, user access control, user information confidentiality, user identity security.

• GPRS is the packet data score network of 3G systems EDGE and WCDMA.

• GPRS system is independent of the characteristics of the radio channel. GPRS provides the following types of data services like MMS, SMS, WAP

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Goals of GPRS :

GPRS is the first step toward an end to end wireless infrastructure as well as communication and has the following goals given below :

• Consistent IP services 
• Open architecture
• Same infrastructure for different air interfaces
• Leverage industry investment in IP
• Integrated telephony and internet infrastructure
• Service innovation independent of infrastructure

What is wireless communication

History of Wireless Communication Technology : 

The birth of a wireless communications system when M.G.Marconi successfully established a radio link between a land-based station and a tugboat in 1901. After that, rapid strides have been made in the realm of wireless communication, enabling live a better life in this digital Era. 

After that what height of achievement wireless communication field reached which is following below year by year is given below:

1901 - Marconi successfully transmit wireless data 
1902 - First two-way communication was successful across the Atlantic
1909 - Marconi won Nobel price

Radio Transmission : 

1914 - First voice radio transmission 
The 1920s - Mobile receivers installed in vehicles First Time

1930s - Mobile transmitters developed and used the First Time 

1935 - Frequency modulation demonstrated the First Time 

Mobile Telecommunication :

1946 - Launch of Public Switched Telephone Network 

The 1960s - Launch of Improved Mobile Telephone Service ( IMTS )

1979 - First cellular communication system developed by NTT ( JAPAN ) 

1983 - Launch of Advanced Mobile Phone System called AMPS 
1989 - Launch of European Digital Cellular Standard for GSM technology by special mobile 
1991 -  Launch US Digital Cellular Phone System 
1993 -  Launch CDMA system
1994 -  Launch GSM system
2001 - Launch 3G technology in Japan 
2007 - 200 million 3G users across the world 
2010 - Nation-wide auction of 3G spectrum in India 

Wireless Local Area Network : 

1990 - Introduction of IEEE 802.11 to define standards for WLAN device
1997 - Introduction of IEEE 802.11 WLAN protocol 
1997 - 50 million cellular users in the US alone 
1999 - Introduction of IEEE 802.11b WLAN protocol 
1999 - Introduction of IEEE 802.11a WLAN protocol 
2000 - Launch of Bluetooth standards 
2003 - Introduction of IEEE 802.11g WLAN protocol 
2008 - Cellular provides no longer required to provide analog support 
2009 - Release of IEEE 802.11n WLAN protocol 

What is WIRELESS COMMUNICATION?

The word wireless is a dictionary defined 'having no wires' in a communication system.

A wireless communication system is the fastest growing and also the most vibrant technological area in the communication field. It is a method of information is transmitting from the transmitter to the receiver side that is placed over a limited distance.    

In wired communication, the medium is a physical path like co-axial cables and optical fiber links which guides the signal to propagate from one point to other is called as Guided Medium. On the other hand, Wireless communication technology doesn't require any physical medium but propagates the signal through space is called as Unguided Medium. 

The question is that if there is no physical medium, even no cables used then how does wireless communication transmit signals?  The transmission and reception of signals are accomplished with Antennas. 

The wireless network device can utilize specific equipment such as NICs and Routers in place of wires (copper or optical fiber used).

Types of wireless communication : 

1. Television and Radio Broadcasting 
2. Satellite Communication 
3. Radar
4. Cellular Communication  
5. GPS Communication 
6. WLAN & Wi-Fi Communication 
7. Bluetooth Communication 
8. Infrared Communication 
9. Paging 
10. Cordless phones 
11. Radio Frequency Identification ( RFID ) 

Explore more information about Wireless Communication : 

Advantages of wireless communication :

• Convenience 
• Mobility 
• Flexibility 
• Less cost 
• Easy to Install 
• A large number of Users 
• Rapid Disaster Recovery 

For detailed information 
Read more >>  Advantages of Wireless communication 

Disadvantages of wireless communication :

• Interface
• Security
• Health 
• Hazardous 

For detailed information 

Read more >> Disadvantages of Wireless communication 

Applications of wireless communication : 

• Wireless power transfer 
• Television remote control 
• Home automation
• Cellular telephone 
• Home and office security systems 
• IoT
• Radar
• Space 
• Military 
• Computer interface devices

For detailed information 

Read more >> Applications of wireless communication 

JFET full form

What is the full form of JFET?

Answer : 

• Junction Gate Field Effect Transistor 

What does JFET mean?

The JFET is one of the simple types of field effect transistor. JFET are three terminal semiconductor devices that can be used as electronically controlled switches, amplifiers, or voltage controlled resistors. 

There is two basic configuration of junction field effect transistor called as N- channel JFET and the P-channel JFET. The N-channel JFET channel is doped with donor impurities meaning that the flow of current through the channel is negative in the form of electrons

WLAN vs bluetooth

Before we learn about the difference between Bluetooth and wireless LAN first let us understand the topic about what is Bluetooth and WLAN. Bluetooth is a short-range technology standard which allows devices to communicate in a wireless manner while in WLAN  that connect two or more devices by using wireless data connection over short distances. Now let us check it out the difference between Bluetooth and WLAN to know more details about this topic.

WLAN vs bluetooth:

• Bluetooth has replaced the cable with wireless network whereas WLAN is developed by WLAN/campus/home.
• In Bluetooth distance range less than 30 feet but in WLAN distance range up to 200 feet.
• In while using minimum distance 10 m,100 m distance with high transmit power while  WLAN 15-150 m /300 m for indoor and outdoor area.
• WLAN size is too much large compared to Bluetooth.
• While using WLAN bandwidth is higher compared to Bluetooth.
• While we are using WLAN cost is high compared to Bluetooth.
• When we are using Bluetooth data rate speed up to 1 Mbps but when we are using WLAN data rate speed up to 24 to 54 Mbps with 5 GHz bandwidth.
• Bluetooth uses in Adhoc network, WLAN no use of piconet. It is effective for random access.
• When we have to use WLAN higher current requirements as compared to Bluetooth.
• In Bluetooth frequency range up to 2.4 GHz whereas WLAN frequency range up to 5 GHz in 20 MHz channels.
• Control access point is require in WLAN.
• In Bluetooth identification of network checking out the Bluetooth control panel but in WLAN identification of network checking out by locating a central router an of a wireless network switch.

Full form of UDP

What is the full form of UDP?

Answer :

• User Datagram Protocol 

What does UDP mean?

TCP and UDP both protocol has a transportation protocol that is one of the core protocols of the internet protocol suite. TCP and UDP work at transport layers TCP/IP model and both have very different usage.

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1. Full form of OSI model

Full form of lifi

What is the full form of Li-Fi?

Answer : 

• Light Fidelity 

What does Li-Fi mean?

Li-Fi is a wireless optical network technology. Li-Fi uses visible light from LED for data transmission. So in unlike infrared-based systems, visible light communication involves to transmitting data using light visible to the human eye. Li-Fi works by flickering light at a rapid-fire rate, invisible to the human eye. To connect to a Li-Fi network to Li-Fi network, a device must be equipped with the capability to recognize the LED light signals and use them to transfer data. A unique security aspect of visible light communication is that it works only when a device has a line of sight to the light transmitter. Light cannot penetrate walls as radio signals can, so drive of wireless internet signals would be far more difficult.

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PPM full form

What is full form of PPM?

Answer :

• Pulse Position Modulation 

What does PPM mean?

PPM is a form of signal modulation, In this method M message bits, are encoded by transmitting a single pulse in one of the possible required time shifts and it can be repeated every T  seconds, such that the transmitting bit rate in bits per second.

PSK full form

What is the full form of PSK?

Answer :

• Phase Shift Keying

What does PSK mean?

PSK is the simplest form of phase shift keying, sometimes it called as BPSK or 2PSK. It can be used phases which are separated by 180 degrees and so can also be termed 2 PSK.

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PAM full form

What is the full form of PAM?

Answer :

• Pulse Amplitude Modulation

What does PAM mean?

PAM is a form of a modulation called as signal modulation, it is part of signal communication where the message information is encoded in the amplitude of a series of signal pulses. PAM is an analog pulse modulation scheme in which the amplitudes of a train of carrier pulses are varied according to the sample value of the message signal is transmitted.

Advantages and disadvantages of AC over DC

We all are aware of the basic concept of AC as well as DC. This article gives information about the advantages and disadvantages or drawback of AC over DC  to know more details about this topic. 

Advantages of AC over DC :

• The generation of A.C is  much more cheaper than that of D.C
• AC can easily be converted into DC with the use an of rectifier
• A.C machines are simple
• The variation of AC can easily be done using transformer either using a step up or step down
• They are robust and also do not require much attention for their repair and maintenance during their use
• In while using AC the loss of energy during transmission is negligible 
• The AC can be easily converted into DC
• The AC generator have higher efficiency compare to DC
• The value or magnitude of AC can be decreased easily without loss of an excess of energy this can be done by only using a device the choke coil
• The AC is easy to generate than DC easily converted into DC
• It is cheaper to generate AC compare DC
• A wide range of voltages are obtained by use of a transformer device
• In AC the magnitude of current can be reduced by using an a conductor or inductance without any appreciable loss of energy
• When AC is supplied at higher voltages in long-distance transmission, the line loss is small compared to a DC transmission side

Disadvantages of AC over DC :

• The peak value of AC is high and it dangerous to use so too much better insulation required
• An AC is transmitted from the surface of the conductor hence need several strands of thin wires insulated from each other
• It attracts a person who touches it unlike DC which gives a repelling shock

Difference between pin photodiode and avalanche photodiode

Before we learn about this article first let we check it out PIN diode and avalanche photodiode (APD), so we have to better understand this article. This article gives information about the difference between a PIN  diode and APD to know more details about it.

PIN diode :

• PIN photodiode does not have a high-intensity electric field region.
• Sensitivity is very low in PIN photodiode.
• The responsibility of a PIN diode is limited.
• Cost is low.
• S/N ratio is very poor.
• Conversion efficiency is 0.5 to 1.0 amps/watt.
• The response time of PIN is half that of APD.
• The detector circuit is very simple.

APD :

• APD is a high-intensity electric field region.
• Sensitivity is very high in APD.
• The responsibility of APD can have much larger values,
• Cost is high.
• S/N ratio is better.
• Conversion efficiency is 0.5 to 100 Amps/watt.
• The response time of APD is almost double that of the PIN,
• The detector circuit is more complex.

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Impulse invariant method example

Step 1 : Analog frequency transfer function H(s) will be given. If it not given then obtain expression of H(s) from the given specification

Step 2 : If required H(s) by using fraction expansion

Step 3 : Obtain Z transform of each PFE term using in-variance transformation equation

Step 4 : Obtain H(z) this is required digital IIR filter

Find out H(Z) using impulse in-variance method at 5 Hz sampling frequency from H(s) as given below :

H(s) = 2 / (s+1) (s+2)

Step 1 : Given analog transfer function is, 

 H(s) = 2 / (s+1) (s+2)

Step 2 : We will expand H(s) using partial fraction expansion as :

H(s) = A₁/s+1 + A₂/s+2

p₁= -1 and p₂ =-2

Step 3 : 

A₁ = s+1 * 2 / (s+1) (s+2)  where s=-1

A₁ = 2/-1+2

A₁ = 2

Same way 

A₂= s+2 * 2 / (s+1) (s+2)  where s=-2

A₂= 2/-2+1

A₂= -2

H(s) = 2/s+1 -  2/s+2

Step 3 : Obtain Z transform of each PFE term using in-variance transformation equation

1 / s-p_k = 1/ 1-e ^p_k^T_s. Z^-1

^1/ F_s = 1/5 = 0.5 sec = ^T_s

_{1/ s+1  →} 1/ 1-e ^-1(0.2) . Z^-1

_{1/ s+1  →} 1/ 1-e ^-0.2 . Z^-1

_{1/ s+2 →} 1/ 1-e ^-2(.2) . Z^-1

_{1/ s+2 →} 1/ 1-e ^-0.4 . Z^-1

Step 4 : Obtain H(z) this is required digital IIR filter

H(Z) = A₁/ 1-e ^p₁^T_s. Z^{-1    +}  A₂/ 1-e ^p₂^T_s. Z^-1

^{H(Z) =} 2/ 1-e ^-0.2 . Z^{-1    -}  2/1-e ^-0.4 . Z^-1

^{H(Z) =  2/ 1-0.818}Z^-1 - 2/ 1-0.67Z^-1

^{H(Z) = 2Z / Z-0.818 - 2Z/ Z-0.67}

H(Z) = 2Z(Z-.67-2Z (Z-0.818) / (Z-0.818)(Z-0.67)

^{H(Z) = 0.29 Z /} Z²-1.488Z+0.54

This require transfer function for digital IIR filter.

Advantages and disadvantages of digital communication

Digital communication is a system that any message pass through digital devices. It is the ability to create communication in different media. It transmits any information by digitally. Now let us check it out a lot of advantages, so we have to know more about digital communication.

Advantages of digital communication :

• It can be done over large distances through internet  devices and other things
• Digital communication technology is easy to mix signals and also have data using digital techniques
• Greater dynamic range is possible
• More option and flexibility in terms of recording and also a reviewing data
• Used in military application
• The inexpensive circuit may be used
• Digital communication gives facilities like video conferencing which save a lot of time, money as well as  effort
• Digital communication is done over a large distance through the Internet and is spread almost in every cities and town. So in the compatibility of digital communication systems with the internet has opened a new area of applications
• Using data encryption, it is very useful for in a military application
• High-speed computers and powerful software design tools are available, so a digital communication system flexible
• It can be tolerated the noise interference
• The digital communication is fast, easier and cheaper
• Digital communication has excellent processing techniques are available for digital signals processing such as processing methods like image processing, video processing, data compression, channel coding and equalization etc
• Much less bulky than analog equivalent
• The error may offer to be corrected with the use of coding
• Much more options being able to share media called both socially and for business

Disadvantages of digital communication :

• High power consumption
• It has a sampling error
• Nongraceful degradation
• Bit error rate or probability of error
• Require A/D conversion at a high rate
• It requires more bandwidth as compared to an analog system
• It needs synchronization in synchronous modulation
• As the square wave is more affected by noise, that's what while communicating through channel we send sine wave but while operating on a device we use squire pulses
• Complex circuit, more sophisticated device making is also disadvantages of a digital system
• More expensive to fix when it does wrong
• It was harder to fix when it does go wrong
• Miss-communication is possible if a user doesn't understand something

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Application of DFT

Before we learn about application of DFT, first let we check it out the DFT stands for Discrete Fourier transform, it is a finite duration frequency sequence which is obtained by sampling one period of Fourier transform. So in sampling is done at 'N' equally spaced points, over the period extending from o to  2π.

• Signal analysis
• Sound filtering
• Data compression
• Partial differentiation equation
• Multiplication of large integer
• Cross correlation
• Matched filtering 
• System identification
• Power spectrum estimation
• Coherence function measurement
• Display signal and spectrum

DFT example

Before we fine DFT first let we check it out the what is DFT.

Find the DFT of the following finite equation sequence of length L.

x(n) = A for 0≤ n ≤   L-1

       = 0 otherwise

We have

  

           N-1

X(K) = ∑    x(n) . e ^–j2πkn/N

             n=0

           N-1

X(K) = ∑    A . e ^–j2πkn/N

            n=0

           N-1

X(K) = ∑    x(n) .( e ^–j2πk/N  ) ⁿ

          n=0

            
We have standard summation formula 

            N2

X(K) = ∑    a ^K   =  a ^N1   - a ^N2+1 / 1- a 

         K=N1

here N1=0, N2 = L-1 and a =  e ^–j2πk/N

          N-1

X(K) = ∑    A [ ( e ^–j2πk/N  )⁰ - .( e ^–j2πk/N  )^L-1+1  /1- e ^{–j2πk/N  ]}

             n=0

           N-1

X(K) = ∑    A [ ( 1 - .( e ^–j2πkL/N  )  / 1- e ^–j2πk/N 

             n=0

Butterworth low pass filters

There are so many digital filters like FIR and IIR filter, here this article gives one more analog type batter-worth filter. To shown in figure typical characteristics of batter-worth low pass filter.

This type of response is called a butter-worth response because its main characteristics are that the pass-band maximally flat. It means there are no variations in the pass-band device.

Now the magnitude squared response of low pass butter-worth filters is given by,

  │H(Ω)²│  =   1   /  1 + (Ω/Ω_c)^2N

Where;

H(Ω) = Magnitude of analog low pass filter

N = Order of the filter

Ω_c = Cut of frequency 

Silent features of low pass butter-worth filter :

• Since the magnitude response is nearly constant at lower frequencies. That means passband and are maximally flat.
• There are no ripples in the passband and also for stopband.
• The maximum gain occurs at the value at Ω = 0 and it is │H(0)│= 1
• The magnitude response is monotonically decreasing.

Application of Butter-worth filter :

• Butter-worth filter can be used as radar such as in designing the display of radar target track.
• In high quality, an audio application,s these are used.
• These are also used in the digital filter for motion analysis.
• This type of filter most commonly used in anti-aliasing filter in data converter applications

Relationship between DFT and Z transform

We already learn about what is DFT and what is Z transform, So now here this article gives the information about the relationship between DFT and Z transform to know more details about DFT as well as Z transform.

The Z transform of sequence x(n) is,

           ∞

X(Z) = ∑  x(n) . Z ^–n

           n=-∞

We know that at Z = e ^–jω

            ∞

X(Z) = ∑  x(n) . e ^–jωn

           n = -∞

It means that X(Z) is evaluated on the unit circle. 

Now suppose X(Z) is sampled at N equally spaced point on the unit circle, then we have 

ω = 2πK / N

Now if X(Z) is evaluated at Z =  e ^–jωk/n then by putting equation we get; 

            ∞

X(Z) = ∑  x(n) . e^{-j2πKn / N}

           n = -∞

At Z = e^j2πK/N

In the equation, if x(n) is a causal sequence and has N number of the sample then we can write an equation

            N-1

X(K) = ∑   x(n) . e^{-j2πKn / N}

           n = 0

At Z = e^j2πKn/N

^{X(K) = X(Z)}  At Z = e^j2πKn/N