Description : The function of ARQ in a network protocol is to: (A) Auto request (B) Acknowledge (C) Address request (D) Abort
Last Answer : (A) Auto request
Description : Network Layer is used for (A) Breaking up the data in frames for transmission (B) Deal with Error correction (C) Automatic Recovery of Procedure (D) Physical Architecture
Last Answer : (D) Physical Architecture
Description : How speech is transmitted in a digital switching environment using PCM/TDM?
Last Answer : A digital carrier system is a communications system that uses digital pulses rather than analogue signals to encode information. Fig shows the block diagram for a digital carrier system. This digital ... to maintain frame and sample synchronization between the TDM transmitter and receiver.
Description : The Signalling connection control part (SCCP) and message transfer part (MTP) together are referred to as (A) Signal Switching Points (SSPs) (B) Signal Transfer Points (STPs) (C) Signal Control Points (SCPs) (D) Network service part (NSP)
Last Answer : (D) Network service part (NSP)
Description : The analog signal needs to be sampled at a minimum sampling rate of: (A) 2fs (B) 1/(2fs) (C) fs/2 (D) 2/fs
Last Answer : (A) 2fs
Description : Companding helps in reducing __________ with respect to signal: (A) Interference (B) Signal overloading (C) Non linearity (D) Quantization noise
Last Answer : (D) Quantization noise
Description : Call request signal is: (A) Seize signal (B) Idle state signal (C) Line identification signal (D) Called subscriber alert signal
Last Answer : (A) Seize signal
Description : Example of circuit switching and S&F (Stored and Forward) switching is (A) Telephone and Post of Telegraph (B) Video Signal Post or Telegraph (C) Digital Signal Post or Telegraph (D) None of above
Last Answer : (A) Telephone and Post of Telegraph
Description : As per Nyquist criterion the sampling rate is (A) 2fs (B) (1/2)fs (C) (1/2fs) (D) (2/fs) Where fs is the signal frequency
Description : An off-hook signal will repeat for a/an ________duration. (A) finite (B) infinite (C) duration of 40 seconds (D) duration of 80 seconds
Last Answer : (A) finite
Description : Echo suppressor is detrimental to full duplex operation because (A) It disables one of the two pairs in a four-wire trunk line when a signal is detected on the other pair. (B) It enables one of the ... It activates both the pairs of a four-wire trunk line. (D) It is independent of line conditions.
Last Answer : (A) It disables one of the two pairs in a four-wire trunk line when a signal is detected on the other pair.
Description : Common channel signalling______________ (A) Uses the speech or data path for signaling. (B) Does not use the speech or data path for signaling. (C) Needs no additional transmission facilities. (D) Finds it difficult to handle signaling during speech.
Last Answer : (C) Needs no additional transmission facilities.
Description : In a time division space switch the size of the control memory is N and its Width: (A)Log10M (B) LogeM (C) LogNM (D) Log2M Where N are the outlets and M the number of data samples
Last Answer : Ans: (It should be 2 log2[N]
Description : What is a Modem? What is the need of MODEM in data communication? Explain at least one modulation technique used for high speed modems.
Last Answer : Modems are essentially used to interface digital circuits to transmit information on analogue channels like telephone systems. Modem (from modulator-demodulator) is a device that modulates an analogue carrier ... caused by the lines makes the detection even harder than amplitude modulation.
Description : Classify data networks. Explain with the help of Nyquist theorem, the data rate limitations in PSTN’s. Give an account of modems used in data transfer. Explain their importance and list some of the V-series recommendations.
Last Answer : Classifications of Data Network: Data Networks are classified according to their geographical coverage: Wide area networks (WANs) Metropolitan area networks(MANs) Local area ... V.53 Limits for the maintenance of telephone type circuits used for data transmission.
Description : A distributed network configuration in which all data/information pass through a central computer is (A) Bus network (B) Star network (C) Ring network (D) Point to point network
Last Answer : (B) Star network
Description : Broad Band ISDN handles data rate of about (A) 64 kbps (B) 100 mbps (C) 5.4 mbps (D) 2.048 mbps
Last Answer : (A) 64 kbps
Description : ISDN handles data pertaining to (A) All digital services (B) Speech and Video (C) Computer data only (D) Speech only
Last Answer : (A) All digital services
Description : Which transmission mode is used for data communication along telephone lines? (A) Parallel (B) Serial (C) Synchronous (D) Asynchronous
Last Answer : (B) Serial
Description : In a hundred-line exchange 24 two-motion selectors are used. Draw the schematic you suggest for this exchange and explain its working. How many simultaneous calls can be made during peak hour in this exchange?
Last Answer : The desired schematic for 100 lines exchange with 24 two motion selectors is shown in Fig. In the case, 24 simultaneous calls can be put through the switch . Typically, a 24- ... selector. At the next step, the two-motion selector responds to the dial pulses for appropriate connection.
Description : How does one arrive at the probability of availability of free lines during the busy hour? How can this be improved?
Last Answer : One can arrive at the probability of free lines during busy hour by using the delay probability of the exchange. The delay probability indicates the delay that a caller may face before his call can be ... may well represent the fraction of the calls lost, which is what the GOS is all about.
Description : Busy hour traffic is the (A) maximum average simultaneous traffic. (B) traffic during peak hour. (C) traffic when all subscribers are engaged. (D) the duration of maximum calls.
Last Answer : (B) traffic during peak hour.
Description : Through two block diagrams explain the difference between Space division and time division switching.
Last Answer : Space and Time Switching: Space Switches: Connections can be made between incoming and outgoing PCM highways by means of a cross point matrix of the form shown in Fig. However, different channels of ... of the speech store, whose contents are read out and sent over the outgoing highway.
Description : What is time multiplexed space switching? With a neat diagram explain its operation.
Last Answer : Time division switches where an inlet or an outlet corresponded to a single subscriber line with one speech sample appearing every 125 µs on the line. Such switches are used in local exchanges. We now ... / Mt , Where t is the switching time including memory access time per inlet-outlet pair.
Description : What is time division switching? With the help of block diagram explain basic time division time switching method.
Last Answer : Time Division Switching: A switching element can be shared by number of simultaneously active speech circuits. This is the principle of time division switching. Obviously, with the way the switching elements are shared in time ... to MDR. This is done by the in-gate and out-gate units.
Description : Using_________each connected device is assigned a time slot whether or not the device has any thing to send. (A) WDM (B) FDM (C) TDM (D) STDM
Last Answer : (C) TDM
Description : Time synchronization is necessary in (A) FDM. (B) TDM. (C) WDM. (D) Quadrature multiplexing
Last Answer : (B) TDM.
Description : In a time multiplexed space switching system, one speech sample appears every (A) 125 micro sec (B) 20 msec (C) 125 msec (D) 1 sec
Last Answer : (A) 125 micro sec
Description : SS7 Protocol uses: (A) Out of band signalling. (B) Associated signalling. (C) Speech control signalling. (D) No signalling.
Last Answer : (A) Out of band signalling.
Description : Common channel signalling in SS7 is (A) out band control channel. (B) in band control channel. (C) speech control channel. (D) none of the above.
Last Answer : (B) in band control channel.
Description : In Go-Back-N ARQ, if frames 4,5, and 6 are received successfully, thereceiver may send an ACK _______ to thesender. A) 5 B) 6 C) 7 D) any of theabove
Last Answer : 7
Description : A transmitted signal 5 meters in wavelength is received by an antenna coil having a 50-Ω resistance and a 0.01 H inductance. What is the capacitance of the tuner shunting the antenna coil at this point? A. 0.704 fF B. 0.704 μF C. 0.704 nF D. 0.704 mF
Last Answer : A. 0.704 fF
Description : What do you mean by numbering and addressing? Draw the ISDN address structure and explain how the addressing works?
Last Answer : Numbering and Addressing: In telephone and data networks, the end equipments are more often single units than multiple devices units like PABX or LAN. Historically, a telephone, a computer, or a ... as reference point may also be addressed by using direct inward dialing (DID) feature.
Description : Explain the process of inter-register signalling.
Last Answer : Registers are used in common control exchanges to store and analyze routing data. They are provided on a common basis is a single register provides routing data for a number of speech circuits. Once a call ... it is released and the originating register signals to the next register.
Description : Draw a centralized SPC organization and explain how it works under load sharing operation.
Last Answer : In centralized control, all the control equipment is replaced by a single processor which must be quite powerful. It must be capable of processing 10 to 100 calls per second, depending on the ... both the processors are active simultaneously and share the load and the resources dynamically.
Description : Explain FDM and show how CCITT standards help in building the base band?
Last Answer : Frequency Division Multiplexing: It is the process of combining several information channels by shifting their signals to different frequency groups within the spectrum so that they can be transmitted simultaneously ... of 24 channels were assembled together in one stage of modulation.
Description : What are transmission bridges? How do they help in satisfying the connectivity?
Last Answer : A typical transmission bridge is shown in Fig. The series capacitance and the shunt inductances of the two relays provide a high-pass filter to transmit the AC speech signals, while the relays respond independently to the DC loop/disconnect signals from the calling and called customer.
Description : What are the different ways of designing 100 line exchange using uni selector and two motion selectors? Show at least three variations. Which is the best option?
Last Answer : Here three different designing methods for 100 line exchange are discussed: Design 1: Here, Strowger switching system is designed using one two-motion selector for each subscriber. A ... only under certain specific traffic conditions and generally lead to higher blocking probabilities.
Description : How numbering plan is achieved in modern telephony? Give the structure with example.
Last Answer : The objective of numbering plan is to uniquely identify every subscriber connected to a telecommunication network. A numbering plan may be open, semiopen or closed. An open-numbering plan permits wide ... known as the subscriber number which is the number listed in the telephone directory.
Description : How does a touch tone receiver differs from pulsed dial receiver? Explain with schematic.
Last Answer : Pulse dialing: 1. Generated through make and break contact. 2. DC Current pulse is generated. 3. Each number is separated by a short pause to prevent overlapping. 4. Codes ... dialing pulse is not misinterpreted as the phone being returned to its on-hook (idle) condition.
Description : Discuss different Routing plan adopted in a Telephone network.
Last Answer : Hierarchical networks are capable of handing heavy traffic where required, and at the same time use minimal number of trunk groups. Three methods are used for deciding on the route for a ... selection methods can be implemented. Computer based routing is a standard feature in data networks.
Description : Discuss briefly subscriber loop system. Give some technical specification for subscriber lines.
Last Answer : Subscriber Loop System: Every subscriber in a telephone network is connected generally to the nearest switching office by means of a dedicated pair of wires. Subscriber loop refers to this pair of wires. It is un ... 1. Diameter of wire 2. D.C. resistance per Km 3. Attenuation per Km
Description : What is Traffic Engineering? Define the term busy hour, traffic intensity and grade of service.
Last Answer : Traffic engineering provides the basis for analysis and design of telecommunication network to carry a given traffic at a particular loss probability. It provides a means to determine the quantum of common equipments ... A0 Where A= offered traffic A0 = carried traffic A-A0= lost traffic
Description : Explain topology method used in LAN technology in detail.
Last Answer : LAN Topologies: Network topology is a physical schematic which shows interconnection of the many users. There are four basic topologies as under: (i) Direct Connection or one to all topology ( ... temporarily, inserting the new node and then reestablishing the complete ring path.
Description : List all seven layer of OSI model and describe function of application layer.
Last Answer : The layers of OSI model are as follows: (1) The Physical Layer: This defines an interface in terms of the connections, voltage levels and data rate, in order for signals to ... with the applications programs needed. Examples include electronic mail, word processing, banking transactions, etc.
Description : Find the total number of link L having five entities? Explain differences between folded and non-folded network.
Last Answer : Folded network: When all the inlets/outlets are connected to the subscriber lines, the logical connection appears as shown in Fig. In this case, the output lines are folded back to the input ... non-folded network to be non-blocking, the network should support N simultaneous switching paths.
Description : Explain simple telephone communication system with circuit and equation of current flow in microphone?
Last Answer : Simple Telephone Communication: In the simplest form of a telephone circuit, there is one way communication involving two entities, one receiving (listening) and the other transmitting (talking). ... carrier wave in AM system. The quantity m is equivalent to the modulation index in AM.
Description : Explain crossbar exchange, with all call processing steps and diagrams
Last Answer : The basic idea of crossbar switching is to provide a matrix of n x m sets of contacts with only n + m activators or less to select one of the n x m sets of contacts. This form of ... a contact is established at the cross point 6 such that the subscriber B is connected to the subscriber C.
Description : What are the advantages and disadvantages of packet switching over circuit switching?
Last Answer : The comparison of packet switching and circuit switching showing advantages and disadvantages of packet switching over circuit switching is given below:
Description : What are the advantages of CCS over in-channel signalling?
Last Answer : The advantages of CCS over in-channel signalling are listed below: a. Information can be exchange between the processors much more rapidly than when channel associated signaling is used. b ... for functions other than call processing, for example for maintenance or network management purposes.