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 : 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 : Analog signals can be ________by combining them with a carrier frequency (A) Carried (B) Transported (C) Multiplexed (D) Mixed
Last Answer : (C) Multiplexed
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 : Show how finite state machine model helps in designing a switching system and give a typical example.
Last Answer : Switching system basically belongs to the class of finite state machines (FSM) which are asynchronous in nature and follows a sequential logic for their operation. They can be modeled by ... circuits and memory elements. Clocked synchronous operation shown in Fig. overcome such problems.
Description : Compare electromechanical switching system with electronic switching system.
Last Answer : Ans:
Description : With neat diagrams explain the configuration of a step-by-step switching system.
Last Answer : The schematic diagram for such an exchange is given in Fig. Each subscriber is connected to a single rotary pre-selector switch at the exchange, the outputs from this switch being ... two further digits, connection is established, providing the called subscriber's to answer his telephone.
Description : Trunks are the lines that run between (A) Subscribers and exchange (B) Switching system and power plant (C) Local area network (D) Switching stations
Last Answer : (D) Switching stations
Description : Trunks are the lines that run between (A) subscribers and exchange (B) switching system and power plant (C) Local Area Network (D) switching systems
Last Answer : (B) switching system and power plant
Description : Trunks are the lines that run between (A) Subscribers and exchange (B) switching system and power plant (C) Local area network. (D) Switching stations.
Last Answer : (D) Switching stations.
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 : 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 : Explain the CCITT hierarchical structure of switching and routing using block schematic.
Last Answer : Hierarchical network are capable of handing heavy traffic where required, and at the same time use minimal number of trunk groups. A 5-level switching hierarchy is recommended by CCITT as ... A strictly hierarchical network suffers from serious drawback i.e. its poor fault tolerance future.
Description : Explain the basic architecture of digital switching systems. Explain in detail companding.
Last Answer : A simple N X N time division space switch is shown in Fig. The switch can be represented in an equivalence form as a two-stage network with N X 1 and 1 X N switching matrices for the first and ... = Parameter used to define the amount of compression Vout = Compressed output voltage.
Description : What is meant by common control? Explain all the categories that are served by Common Control switching.
Last Answer : In some switching systems, the control subsystem may be an integral part of the switching network itself. Such system is known as direct control switching systems. Those systems in which the control ... may be carried out at the level of the common control unit or the switching network.
Description : Name the switching schemes used in a digital exchange. How call processing takes place?
Last Answer : The different switching systems used are: 1. Strowger Switching System 2. Cross bar Switching. 3. Electronic Switching System Basic Call Procedure: Fig. Shows a simplification ... machine detects an open circuit on that loop and then drops the connections through the switch.
Description : What is store program control (SPC)? Give the organization of centralized SPC. Discuss the advantages of SPC automation in telephone switching.
Last Answer : In stored program control systems, a program or set of instructions to the computer is stored in its memory and the instructions are executed automatically one by one by the processor. Carrying out ... of services can be provided to customers. (v) Increase level of automotive in switching
Description : A two stage non-blocking network requires twice the number of switching elements as the single stage non-blocking network. (A) TRUE (B) FALSE
Last Answer : Ans: (A)
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 : Packet switching is used for (A) Credit card verification (B) Automated Teller Machine (C) The internet and the World Wide Web (D) All of the above
Last Answer : (D) All of the above
Description : Traffic Handling Capacity is given by (A) Switching capacity ×Theoretical maximum load (B) Switching capacity / Theoretical maximum load (C) Theoretical maximum load / Switching capacity (D) Theoretical maximum load + Switching capacity
Last Answer : (B) Switching capacity / Theoretical maximum load
Description : In step by step switching line finders are connected to the (A) Calling subscriber. (B) Switching network. (C) Called subscriber. (D) Between exchanges.
Last Answer : (A) Calling subscriber.
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 : For two stage network the switching elements for M inlets with r blocks and N outlets with s blocks is given by (A) Ms + Nr (B) Mr + Ns (C) (M + N) (r + s) (D) (M + N)rs
Last Answer : (A) Ms + Nr
Description : SPC stands (A) Standard Protocol Control (B) Stored Program Control (C) Signaling and switching Centre (D) Signaling Process Center
Last Answer : (B) Stored Program Control
Description : The final selector is connected to the (A) calling subscriber. (B) switching network. (C) called subscriber. (D) line finder.
Last Answer : (C) called subscriber
Description : Traffic Capacity is given by (A) Switching capacity × Theoretical maximum load (B) Switching capacity / Theoretical maximum load (C) Theoretical maximum load / switching capacity (D) Theoretical maximum load × Switching capacity
Last Answer : (A) Switching capacity × Theoretical maximum load
Description : A sample rate of ________is required for a good quality representation of telephone conversation. (A) 4500 times per second. (B) 700 integer sample points per minute. (C) 50 times per second per mile of distance travelled. (D) 8000 times per second.
Last Answer : (C) 50 times per second per mile of distance travelled.
Description : The CCITT standard bandwidth for speech is: (A) 20000 Hz (B) 15000 Hz (C) 7000 Hz (D) 3400 Hz
Last Answer : (D) 3400 Hz
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 : Side tone is the speech heard by (A) the receiving subscriber (B) both the receiving and calling subscriber (C) by on looker (D) by calling subscriber
Last Answer : (D) by calling subscriber
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 : 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 LAN network every system is identified by (A) Name (B) MAC address (C) IP Address (D) Serial number given by manufacturer
Last Answer : (C) IP Address
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 : A certain population of ALOHA users manages to generate 70 request/sec. If the time is slotted in units of 50 msec, then channel load would be a. 4.25 b. 3.5 c. 350 d. 450
Last Answer : b. 3.5
Description : The access time of ROM using bipolar transistors is about (A) 1 sec (B) 1 msec (C) 1 µsec (D) 1 nsec.
Last Answer : Ans: C The access time of ROM using bipolar transistors is about 1 µ sec.
Description : A disk drive has 100 cylinders, numbered 0 to 99. Disk requests come to the disk driver for cyclinders 12, 26, 24, 4, 42, 8 and 50 in that order. The driver is currently serving a request at cyclinder 24. A seek takes ... (SSTF) algorithm? (A) 0.984 sec (B) 0.396 sec (C) 0.738 sec (D) 0.42 sec
Last Answer : C
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 : 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 : ARQ is transmitted in the event of: (A) Loss of signal (B) Error in received data (C) Improve reliability (D) During time out
Last Answer : (B) Error in received data
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 : 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.