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DIGITALTRANSMISSION TECHNOLOGY
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DIGITALTRANSMISSION TECHNOLOGY

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DIGITALTRANSMISSION TECHNOLOGY BY V.S.ARJUN

DIGITALTRANSMISSION TECHNOLOGY BY V.S.ARJUN

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  • http://www.collaborationideas.com/wp-content/uploads/2011/06/cloudcomputing.jpgHopefully, you now have a better understanding of how the cloud works and ways you can protect yourself. Thanks for listening!
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    • 1. PRESENTATION BY :
    • 2. Transmission systems interconnect communication devices by guiding signal energy in a particular direction or directions through a transmission medium such as copper, air, or glass. DIGITAL TRANSMISSION is the transmission of digital signals between two or more points in a communications system. DTS use both metallic and optical fiber cables for their transmission medium.
    • 3. Noise immunity Long distance communication Easy Storage & processing Errors can be easily detected & corrected More accurate ADVANTAGES
    • 4. DISADVANTAGES • More bandwidth required • Additional encoding & decoding circuitary required. • synchronization of transmitter & receiver clocks required
    • 5. Multiplexing (also known as muxing) is a method by which multiple analog message signals or digital data streams are combined into one signal over a shared medium. The aim is to share an expensive resource For example, in telecommunications, several telephone calls may be carried using one wire. •George Owen Squier is credited with the development of multiplexing in 1910.
    • 6. MULTIPLEXING • can extract the original channels on the receiver side. DEMUX (Demultiplexing ) • A device that performs the multiplexingMULTIPLEXER • A device that performs the demultiplexingDEMULTIPLEXER
    • 7. MULTIPLEXING (MUX) General multiplex scheme: the ν input lines-channels are multiplexed into a single fast line. The de multiplexer receives the multiplexed data stream and extracts the original channels to be transferred
    • 8. MULTIPLEXING (MUX) SPACE-Division Multiplexing (SDM) FREQUENCY-Division Multiplexing (FDM) TIME-Division Multiplexing (TDM) CODE Division Multiplexing(CDM) Multiplexing technologies may be divided into several types
    • 9. SPACE-DIVISION MULTIPLEXING • In wired communication, space-division multiplexing simply implies different point-to- point wires for different channels. • Examples include an analogue stereo audio cable, with one pair of wires for the left channel and another for the right channel, and a multipair telephone cable.
    • 10. Examples
    • 11. FREQUENCY-DIVISION MULTIPLEXING • The spectrum of each input signal is shifted to a distinct frequency range. • It is an analog technology • One of FDM's most common applications is cable television.
    • 12. TIME-DIVISION MULTIPLEXING • Time-division multiplexing (TDM) is a digital (or in rare cases, analog) technology. • TDM involves sequencing groups of a few bits or bytes from each individual input stream, one after the other, and in such a way that they can be associated with the appropriate receiver.
    • 13. Fig. Time-division multiplexing (TDM)
    • 14. CODE-DIVISION MULTIPLEXING • Code division multiplexing (CDM) or spread spectrum is a class of techniques where several channels simultaneously share the same frequency spectrum, and this spectral bandwidth is much higher than the bit rate. • One form is frequency hopping, another is direct sequence spread spectrum. • Advantages over conventional techniques are that variable bandwidth is possible
    • 15. • Code Division Multiplex techniques are used as an channel access scheme, namely Code Division Multiple Access (CDMA), e.g. for mobile phone service and in wireless networks. • Another important application of CDMA is the Global Positioning System (GPS).
    • 16. FOUR Methods of pulse modulation: • Pulse Amplitude Modulation • Pulse Width Modulation • Pulse Position Modulation • Pulse Code Modulation PULSE MODULATION The process of transmitting signals in the form of pulses (discontinuous signals) by using special techniques.
    • 17. Analog Pulse Modulation Digital Pulse Modulation Pulse Amplitude (PAM) Pulse Width (PWM) Pulse Position (PPM) Pulse Code (PCM) Delta (DM) Pulse Modulation Pulse Amplitude Modulation (PAM): * The signal is sampled at regular intervals such that each sample is proportional to the amplitude of the signal at that sampling instant. This technique is called “sampling”. * For minimum distortion, the sampling rate should be more than twice the signal frequency.
    • 18. AND Gate Pulse Shaping Network FM Modulator Analog Signal PAM - FM Pulses at sampling frequency HF Carrier Oscillator PAM Pulse Amplitude Modulator Analog Signal Amplitude Modulated Pulses
    • 19. * In this type, the amplitude is maintained constant but the duration or length or width of each pulse is varied in accordance with instantaneous value of the analog signal. * The negative side of the signal is brought to the positive side by adding a fixed d.c. voltage. Analog Signal Width Modulated Pulses Pulse Width Modulation (PWM or PLM or PDM):
    • 20. * In this type, the sampled waveform has fixed amplitude and width whereas the position of each pulse is varied as per instantaneous value of the analog signal. * PPM signal is further modification of a PWM signal. It has positive thin pulses (zero time or width) corresponding to the starting edge of a PWM pulse and negative thin pulses corresponding to the ending edge of a pulse. * This wave can be further amended by eliminating the whole positive narrow pulses. The remaining pulse is called clipped PPM. PWM PPM Pulse Position Modulation (PPM):
    • 21. PAM, PWM and PPM at a glance: Analog Signal Amplitude Modulated Pulses Width Modulated Pulses Position Modulated Pulses
    • 22. PULSE CODE MODULATION It was only in 1938,Mr. A.M. Reaves (USA) developed a Pulse Code Modulation (PCM) system to transmit the spoken word in digital form.  Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, Compact Discs, digital telephony and other digital audio applications In a PCM stream, the amplitude of the analog signal is sampled regularly at uniform intervals, and each sample is quantized to the nearest value within a range of digital steps To develop a PCM signal from several analogue signals, the following processing steps are required • Filtering • Sampling • Quantization • Encoding • Line Coding
    • 23. * Analog signal is converted into digital signal by using a digital code. * Analog to digital converter employs two techniques: 1. Sampling: The process of generating pulses of zero width and of amplitude equal to the instantaneous amplitude of the analog signal. The no. of pulses per second is called “sampling rate”. 2. Quantization: The process of dividing the maximum value of the analog signal into a fixed no. of levels in order to convert the PAM into a Binary Code. The levels obtained are called “quanization levels”. * A digital signal is described by its „bit rate‟ whereas analog signal is described by its „frequency range‟. * Bit rate = sampling rate x no. of bits / sample Pulse Code Modulation (PCM):
    • 24. Time V o l t a g e 7 6 5 4 3 2 1 0 111 110 101 100 011 010 001 000 L e v e l s B i n a r y C o d e s Time Time V o l t a g e 0 1 0 1 0 1 1 1 0 1 1 1 1 1 0 1 0 1 0 1 0 Sampling, Quantization and Coding
    • 25. EVOLUTION OF DIGITAL MULTIPLEXING Fig. Transport Technologies Evolution
    • 26. Plesiochronous digital hierarchy (PDH) PDH is a Multiplex hierarchy. The PDH signals are the 2.048 Mbit/s signal that carries 30 voice channels, the 8.488 Mbit/s signal that multiplexes four 2.048 Mbit/s signals, the 34.368 Mbit/s signal that multiplexes four 8.488 Mbit/s signals, and the 139.264 Mbit/s signal that multiplexes four 34.368 Mbit/s signals.
    • 27. PDH MULTIPLEXING STRUCTURE
    • 28. PDH Bit Rates
    • 29.  COMPLICATED MUX/DMUX TECHNIQUE  NO COMMON STANDARD  POOR MANAGEMENT • NO PROTECTION & PROBLEM OF INTER NETWORKING • VENDER DEPENDENT • PROBLEM OF CROSS-CONNECTION • NEARLY SYNCHRONOUS DRAWBACK OF PDH SYSTEM
    • 30. Synchronous Digital Hierarchy (SDH) • Synchronous Digital Hierarchy (SDH) is standardized protocols that transfer multiple digital bit streams over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs). • SDH IS AN ITU-T STANDARD FOR A HIGH CAPACITY TELECOM NETWORK. • SDH IS A SYNCHRONOUS DIGITAL TRANSPORT SYSTEM, AIM TO PROVIDE A SIMPLE, ECONOMICAL AND FLEXIBLE TELECOM INFRASTRUCTURE.
    • 31. WHY SDH SYSTEM • GLOBAL STANDARD • MULTI-VENDER DEPENDENT • SIMPLIFIED MUX/DMUX TECHNIQUE • POWERFUL MANAGEMENT • POWERFUL PROTECTION
    • 32. SDH SYSTEMS SYSTEM BITE RATE No. OF CHANNELS STM-1 155.52 Mbps 1890 STM-4 622.08 Mbps 7560 STM-16 2.5 Gbps 30240 STM-64 10 Gbps 120960 STM-256 40 Gbps 483840
    • 33. SDH/PDH RATES SDH 140 Mbit/s 34 Mbit/s 8 Mbit/s 2 Mbit/s Nx45 Mbit/s 100 Mbit/s 45Mbit/s 6,3 Mbit/s 1,5 Mbit/s 32 Mbit/s 6,3 Mbit/s 1,5 Mbit/s 400 Mbit/s PDH PDH EUROPE PDH JAPAN PDH NOTH AMERICA Level 1 Level 4 Level 3 Level 2 STM64 10Gbit/s STM4 620Mbit/s STM1 155Mbit/s STM16 2,48Gbit/s
    • 34. ADVANTAGES OF SDH • HIGH TRANSMISSION RATES • SIMPLIFIED ADD &DROP FUNCTION • HIGH AVAILABILITY AND CAPACITY MATCHING • RELIABILITY • FUTURE-PROOF PLATFORM FOR NEW SERVICES • INTERCONNECTION • SDH SUPPORTS PDH SIGNALS
    • 35. SDH APPLICATION AREAS • SDH systems are used in almost all areas of telecommunication network. Some of the applications areas are given below. • Access Network • Aggregation Network • Metro Network • Long distance National as well as International • Wireless Backhauling • SCADA (Supervisory Control and Data Acquisition)
    • 36. Racks of Alcatel STM-16 SDH add-drop multiplexers
    • 37. Thank you!!

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