Real Time Aricent Technologies Technical Interview Questions and Answers PDF
• What Is An Oscillator? Give An Application Of It?Oscillator is a circuit that generates a waveform output for a direct current input. There are mainly two types of oscillators – harmonic (which have smooth curved waveforms) and relaxation (which have waveforms with sharp edges). Example – speakers etc.
• What Is Am? Give A Brief Description Of Its Working?
AM stands for Amplitude Modulation which is an analog modulation technique where amplitude of carrier (high frequency) signal is varied in accordance with the message (low frequency) signal. It is used for video signals for example TV etc. which operate in the frequency range of 535-1705 KHz.
• Hat Is Fm? How Does It Work? Explain The Difference Between Am And Fm?
FM stands for Frequency Modulation which is an analog modulation scheme where frequency of the carrier signal is varied according to the message signal unlike amplitude in AM. For a binary signal which has only two possibilities – 0 and 1, two carriers (with different frequencies) are used for denoting 0 and 1. It is used for audio signals for example Radio etc. which operate in the frequency range of 88-108 MHz.
• What Is Modulation And Why Is It Necessary?
Modulation is the process of varying the characteristics of a high frequency carrier signal (i.e. amplitude, frequency or phase) in accordance with the low frequency message signal. When a signal is transmitted, noise gets added through the environment, channel/medium of communication, transmitter/receiver incapability etc. which sometimes adversely affects the low frequency signal transmitted (without modulation) resulting in decaying of information to be sent. Thus, the low frequency baseband signal is modulated over a high frequency carrier signal to minimize the effect of noise for effective transmission of information even over long distances.
• What Is Demodulation And Why Is It Necessary?
Demodulation is the process of removing the modulation from the received analog signal to obtain the original message signal sent by the transmitter in order to interpret the information to be communicated.
• What Are Active And Passive Components? Give Examples Of Both?
Active components are components that produce energy (in the form of voltage or current) such as transistors, while passive components consume energy like resistor, capacitor etc.
• Why Is Input Resistance Of An Operational Amplifier High And Output Resistance Low?
Input resistance of an op-amp is kept high for efficient loading at input and maximum transfer of input to the output end (and output end to load) because op-amp acts as an current exchange device from input to output.
• What Is Gsm?
GSM, which stands for Global System for Mobile communication, is a second generation (2G) cellular standard under ETSI (European Telecommunication Standards Institute) developed to cater voice services and data delivery using digital modulation. Earlier called Group Speciale Mobile, it was founded in 1982 to replace the incompatible analog (1G) system.
• What Is Cdma?
Code Division Multiple Access, briefly known as CDMA, is a channel access technique used for radio/wireless communication between the Mobile Station and Base Station. It uses different orthogonal codes for different users to allow multiple users to be multiplexed over the same physical channel simultaneously.
• What Is The Main Difference Between Gsm And Cdma?
The main difference between the two is the multiplexing technique they use for the wireless communication between the Mobile Station and Base Station. CDMA uses different orthogonal (i.e. non-overlapping) codes for multiple users such that any number of users can communicate with each other without any interference by others (due to orthogonality). On the other hand, GSM uses narrowband TDMA as the channel access scheme in which multiple users are assigned different time slots in which they can use the entire bandwidth available. It can allow eight calls on the same frequency simultaneously.
• What Is Tdma And Fdma? Explain Their Difference?
TDMA refers to Time Division Multiple Access which is a channel multiplexing technique where users are assigned different time slots such that eight simultaneous calls can be made using the entire bandwidth. FDMA stands for Frequency Division Multiple Access which is also a channel multiplexing technique where users are assigned different frequency bands within which they can operate at any point of time.
• In Which Case Is Noise Low – Cdma Or Gsm And Why?
Noise is low in the case of CDMA because it uses orthogonal codes for different users which are non-overlapping so there is no interference due to other coded signals even if they overlap with the desired signal.
• What Is Transducer? Give An Example?
Transducer is a device that converts any physical quantity into an electrical signal for example Cathode Ray Oscilloscope (CRO).
• What Is Transponder?
Transponder refers to TRANS-resPONDER which is a device that receives, amplifies, and then retransmits the (reply) signal to a different frequency upon proper verification of the received signal.
• What Is Handoff? Give A Brief Description About Its Types?
When a mobile user moves from one cell to another (i.e. changes its cell), earlier channels are required to be disconnected and new channels have to be allocated by the new cell. A process must be there to avoid call drop due to low minimum usable power of the Mobile Station. This process is called handoff or handover. There are two types of handoffs – Soft (in which new connection is established before disconnecting the previous one thus is more efficient but more costly, mostly used for cell phone calls) and Hard (in which connection from previous cell is disconnected before establishing a connection with the new cell. More affordable but is used for the services that can allow slight delays, such as mobile broad band internet).
• What Is Half-duplex Channel? Give A Real-life Application Of It?
Half-duplex channel is a medium of communication in which the sender and receiver are capable of transmitting or receiving but not both at the same time for example, a walkie-talkie.
• What Is Full-duplex Channel? Give An Example?
Full-duplex channel is a medium of communication in which the sender and receiver are capable of transmitting or receiving and both can transmit/receive at the same time for example, a telephone.
• What Is Osi? Explain The Osi Layers In Order.?
OSI stands for Open Systems Interconnection. For data communication, the ISO (International Standard Organization) has given a layered framework for understanding and designing purpose,nk called as OSI. The overall task is subdivided in multiple levels, each called a Layer. The entire process of data transmission is broken down to network functions. The network functions are grouped as per their characteristics & each group of functions is called a layer. All the OSI layers can be briefly described as follows.
• At Which Osi Layer Does The Retransmission Of Packets Take Place?
The retransmission of packets takes place in the Network layer of OSI model.
• Explain Tcp/ip. Give Their Real-life Applications.?
TCP/IP stands for Transmission Control Protocol/Internet Protocol and is a basic, connection-oriented and reliable transport protocol of the Internet. TCP offers full-duplex service in which data can flow in both directions at the same time. It adds reliability and connection-oriented features to the services of IP. It is a three-phase service which implies that two TCPs establish a dedicated connection between themselves in the first, transfer data in the second and then release the path in the third phase. It can be used for secure online payment transactions as it uses Acknowledgement (ACK) mechanism to check the safe arrival of data.
• Give A Brief Description About Circuit Switching And Packet Switching.?
Circuit switching is a type of method for implementing a telecommunication network in which a dedicated path or physical connection is established before transmission of data. Dedicated connection allows full-duplex, fast, safe and reliable transmission of data. After the data transfer, the path is released. Example – voice communication (telephone etc.).
Packet switching is a digital networking method for (half-duplex) communication in which data is divided into small segments (called packets) which are transmitted over a medium that is shared between parties in a network. Example – data communication (internet etc.).
• What Is Inter-symbol Interference (isi)?
Inter-Symbol Interference or ISI is defined as the crosstalk between the signals of the same channel/sub-channel which are separated in time by a finite interval. In simple terms, it is the distortion in the desired signal caused due to the interference by the signals of the same channel to which it belongs.
• What Is Inter-channel Interference (ici)?
Inter-Channel Interference or ICI is defined as the distortion in the desired signal due to interference caused by the signals of other channels in the surrounding of the desired signal.
• What Is Adjacent Channel Interference (aci)?
Adjacent Channel Interference or ACI is the distortion in the desired signal caused due to interference by signals that are adjacent in frequency of the desired signal. ACI can be minimized through careful filtering and channel assignments.
• What Is Near-far Effect? Where Does It Happen?
Due to Adjacent Channel Interference (ACI) which is caused due to imperfect filters, nearby frequencies leak into the passband of the receiver. This problem can be particularly serious if a large number of channel users are transmitting in a very close to a subscriber receiver. This situation is referred to as Near-Far effect where a nearby transmitter captures the receiver of the subscriber and happens in the case of CDMA in which multiple users operate on the same frequency with different orthogonal codes. Any error in assigning the codes to the users can cause this problem.
• What Is The Difference Between Microprocessor And Microcontroller?
Microprocessor is an integrated circuit that only has processor (i.e. CPU – Central Processing Unit) inside it and requires RAM, ROM, peripheral devices such as keyboard, seven-segments etc. to be externally interfaced to it. Microcontroller, on the other hand, has IO (Input/Output) ports, fixed amount of RAM and ROM in addition to a processor on the chip. Microprocessor is generic device that can be used for any purpose but microcontroller is task-specific and can only perform the task for which it has been designed. Click here to know more differences.
• Why Is Multiplexing Used?
Resources are limited and number of people using mobile phone and internet services are increasing day by day, so to provide efficient access to all users, multiplexing is used as it allows to share expensive resources among all.
• Is 8086 A Microprocessor Or Microcontroller? What Is The Maximum Clock Frequency Of It?
8086 is a microprocessor which has a maximum clock frequency of 5 MHz.
• What Are The Various Segment Registers In 8086?
8086 has four segment registers – Code Segment (CS), Data Segment (DS), Stack Segment (SS), and Extra Segment (ES).
• Explain The Contents Of Psw In 8051?
The 8051 microcontroller has the following bits (in order from bit 7 to bit 1) in the Program Status Word (PSW) – carry flag, auxiliary carry flag, user flag 0, Register bank Select bit one (RS1), Register bank Select bit zero (RS0), overflow flag, reserved bit, and parity flag.
• What Are The Different Flags Supported By The 8086 Microprocessor?
The 8086 microprocessor has the following flags – carry flag, auxiliary carry flag, parity flag, zero flag, overflow flag, trace flag, interrupt flag, direction flag, and sign flag.
• Which Type Of Stack Is Used In 8086?
The 8086 microprocessor uses LIFO (Last In First Out) stack in which the element which is inserted last, gets removed first.
• What Is Stack Pointer?
Stack Pointer or SP is a Special Function Register (SFR) in microprocessor/microcontroller which contains the address of the top of the stack.
• What Is Program Counter?
Program Counter or PC is a Special Function Register (SFR) in microprocessor/microcontroller which contains the address of the first byte of next instruction or next byte of a multi-byte instruction to be fetched for execution of a program.
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