MODULATION Systems (part 1)
|
|
- Anna Hutchinson
- 5 years ago
- Views:
Transcription
1 Technologies and Services on Digital Broadcasting (8) MODULATION Systems (part ) "Technologies and Services of Digital Broadcasting" (in Japanese, ISBN ) is published by CORONA publishing co., Ltd. Copying, reprinting, translation, or retransmission of this document is prohibited without the permission of the authors and the publishers, CORONA publishing co., Ltd. and NHK. In the past, digital transmission of video and audio has required a broader frequency bandwidth than analog transmission to transmit the same information. Recent progress in source coding technology for video and audio, however, has made it possible to reduce the bit rate while keeping the quality deterioration to a minimum. The frequency bandwidth required for digital transmission has consequently become about the same as or several fractions that of analog transmission, making digital transmission feasible for broadcasting. Until recently, digital transmission systems for broadcasting have consisted mainly of multiplex broadcasting systems transmitting only audio and text data. Today, digital transmission including video services is possible in the form of satellite and terrestrial digital broadcasting. In this issue, we describe the basics of digital modulation systems. Figure shows a digital transmission system. The system quantizes and samples analog information such as video or audio data and performs source coding on that data for the purpose of band compression. It then performs channel coding, which consists of adding error correction code to correct the errors generated during transmission, as well as data interleaving and digital modulation. The system converts the digitally modulated signal into one in the transmission frequency band, amplifies that signal at the transmitter, and transmits it by either radio wave or cable. At the receiver, the system performs inverse processing with respect to the transmission side to restore the original information; that is, it digitally demodulates the received signal, performs de-interleaving and error correction, etc.. Digital baseband signal information received information. Basic code A data stream consisting of 's and 's can be transmitted as a pulse train generated, for example, by the voltage of an electrical signal. Basic binary codes for such a pulse train are shown in Figure 2. Referring to the figure, "unipolar" means that the input data and correspond to voltages of and +, respectively, while "bipolar" means that the input data source coding source decoding error correction coding error correction decoding Bit stream Channel coding digital modulation digital demodulation Figure : Digital transmission system transmitter receiver transmission path and correspond to voltages of - and +, respectively. Here, RZ (Return to Zero) results in a narrower pulse width, which means that the frequency bandwidth is wider than in NRZ (Non Return to Zero). For this reason, NRZ is more often used as a baseband signal for digital modulation of radio transmissions. Unipolar NRZ Bipolar NRZ Unipolar RZ Bipolar RZ - Digitally modulated signal T - Figure 2: Basic binary codes.2 Digital signal spectrum The power spectrum density (PSD) of a A (Volt) bipolar-nrz random signal is given by the following expression. () Here, T is the NRZ symbol period (sec). A symbol is the minimum unit of code transmission. In this case, one symbol corresponds to one bit. The inverse of the symbol period /T is called the symbol rate (symbol/sec) or baud rate. Broadcast Technology no.4, Spring 23 C NHK STRL
2 Lecture PSD [db] The NRZ PSD is shown in Figure 3. The vertical axis is normalized in terms of A 2 T. Null points corresponding to zero power appear at frequencies corresponding to various symbol rates for the case of an infinitely large bandwidth..3 Transmission path noise Noise on a transmission path or in a receiver can be broadly classified into thermal noise, generated from resistors, and artificial noise, from sources such as automobiles that reach the receiving antenna. For relatively clean links like satellite channels and cables, the noise on the transmission path can be considered to be mostly thermal. As shown in Figure 4, the temporal waveform of thermal noise is random in nature; its amplitude distribution follows a Gaussian distribution (normal distribution), whose probability distribution function (PDF) is shown in Figure 5. The average amplitude m of thermal noise is. Given a noise power of amplitude /T -3/T -2/T -/T /T 2/T 3/T 4/T Figure 3: NRZ power spectrum density frequency, P(x) is the probability that the thermal noise will take on a certain amplitude. The PSD of thermal noise is given as follows. (2) The PSD of thermal noise is thus flat over all frequencies, a condition referred to as "white noise." The above temporal and frequency characteristics are reflected by thermal noise often being called "white Gaussian noise.".4 Errors on a transmission path having noise and distortion At the receiver, transmitted digital data are judged to be or based on the signal level, which is greater or less than a threshold level, at symbol sample points. The system disregards times other than the sample points, regardless of the type of waveform. Rectangular pulses, such as the NRZ and RZ pulses described earlier, have large bandwidths (infinitely large in theory). Therefore, to make efficient use of finite frequency resources, appropriate band limitations are applied to the transmission, resulting in the smooth waveform shown in Figure 6(b). If non-linear distortion and reflection occur on the transmission path, prior and subsequent symbols with respect to the symbol in question will be affected and signal levels at sample points will vary. This distortion is called Inter Symbol Interference (ISI). If the ISI is large, the margin of the threshold level with respect to noise drops, and this lesser margin becomes a source of error. If noise is added to the signal, levels may exceed the threshold level and errors may be generated as shown in Figure 6(d). -3 Figure 4: Temporal waveform of thermal noise ( =) (a) no band limitation P(x) (b) band limit m x (c) band limit + ISI error ISI When mean =, Figure 5: Gaussian probability distribution function (d) band limit + ISI + noise error Figure 6: Transmission path having distortion and noise Broadcast Technology no.4, Spring 23 C NHK STRL
3 Transmission errors are evaluated in terms of error rate. For example, one erroneous bit in a transmission of bits of information corresponds to a bit error rate (BER) of -3. We consider errors caused by noise. If we were to superpose Gaussian noise of variance (noise power) (Figure-5) on signals of amplitudes -A and +A corresponding to codes and, the amplitude distribution at a sample point would be expressed as P(x) and P(x) as shown in Figure 7. (4) The above equation can be referred to as a "," where is the " rate." The baseband bandwidth B b is (5) P(x) Area in which code is mistaken as -A +A P(x) Area in which code is mistaken as Figure 7: Error caused by Gaussian noise Amplitude The error rate Pe is the areal percentage of that part exceeding level. It is computed as follows. Pe = (probability that code is sent) (probability that code is mistaken as ) + (probability that code is sent) (probability that code is mistaken as ) Given that the probability of sending code and that of code are both /2, we can rewrite the above as follows. In the above equation, T s is symbol period and (=/ T s ) is symbol rate. As decreases, the bandwidth of the pulse series becomes smaller, and jitter (variance at the sampling point) can easily occur. As increases, the bandwidth becomes larger. The minimum bandwidth corresponding to = is called the Nyquist bandwidth. For example, the following baseband bandwidth is needed when transmitting a -Mbps NRZ binary signal at a rate of.5. B b = ( +.5) / 2 Mbps / ( bit/symbol) = 7.5 MHz The S/N of the received pulse becomes a maximum on a linear transmission channel if the frequency response of the transmitter and receiver s behave as if they share a H(f) =.5 =.5 = Here, (3) is called the co-error function. fts.5 Roll-off Characteristic h(t).5 Condition for undistorted transmission If band limitations are applied to an NRZ rectangular pulse, ISI will occur in the waveform. Considering, however, that the absence of disturbances from other samples is desirable at a sample point, we note that ISI will not occur (ISI-free transmission) if, for any pulse, the amplitude at the sampling point is non-zero while the amplitude at all other sample points for that pulse is zero. This condition is called the Nyquist criterion. A band-limited that satisfies the Nyquist criterion and its impulse response are shown in Figure 8. Here, the frequency characteristics are given as.5 Impulse Response = = Figure 8: Roll-off characteristics and pulse that satisfies the Nyquist criterion t/ts 2 Broadcast Technology no.4, Spring 23 C NHK STRL
4 Lecture in the transmission line. It is therefore common to subject the characteristics to root allocation in the transmitter and receiver as shown in Figure 9. This is called "root." NRZ It should be emphasized that the above characteristics produce an undistorted transmission for an input signal having an ideal impulse. However, as an actual transmission pulse has a width, frequency compensation using reverse characteristics of that spectrum results in a flat spectrum, like the frequency response of an impulse. This is called aperture equalization, and it can be expressed as follows in the case of NRZ. Aperture equalization is usually done together with rolloff ing. An example of characteristics that include NRZ aperture equalization is shown in Figure. 2 x/sin x (aperture) White Gaussian Noise Figure 9: Root s in a transmission system H(f) =.5 A(f) H(f) A(f) aperture equalization.5 fts NRZ Figure : Roll-off characteristics including aperture equalization The received waveform is in a disturbed state, due to the effects of distortion and noise in the transmission path. This state can be observed in the form of eye patterns. Specifically, if the received signal is displayed on an oscilloscope overlaid by the symbol period, blank areas become visible in the center of the resulting output. These - - Figure : Examples of eye patterns ( =.5; left: no noise, right: with noise) (6) are called eye patterns because of their resemblance to eyes. The size of a single eye here can be used to visually assess the extent of waveform distortion. For example, a "closed" eye means that 's and 's cannot be distinguished and the code error is large. Note that there is one eye in a single eye pattern for a binary signal and M- eyes for an M-dimensional signal. Figure shows examples of eye patterns. 2. Digital modulation systems As in analog modulation, the function of "modulation" in digital modulation is to convert the original information signal (baseband signal) into one with a frequency convenient for transmission and to vary the amplitude, frequency, or phase of the carrier. What is different from analog modulation is that the baseband signal in question may be an analog signal or a digital signal. Varying the amplitude of the carrier (as in AM) according to the 's and 's in the baseband signal is called amplitude shift keying (ASK), varying the frequency of the carrier (as in FM) is called frequency shift keying (FSK), and varying the phase is called phase shift keying (PSK). Varying both amplitude and phase, moreover, is called quadrature amplitude modulation (QAM). We here describe several basic examples of such systems, namely, BPSK, QPSK (4PSK), and 6QAM. 2. BPSK (Binary Phase Shift Keying) The most basic form of PSK is BPSK. As shown in Figure 2, BPSK transmits a binary ( and ) digital signal by having a carrier phase of correspond to. The configuration of the BPSK modulator is shown in Figure 3. BPSK is a system that sends one bit of information per symbol. Because information is conveyed by phase, BPSK is robust against level fluctuation on the transmission path. As shown in Figure 4, the BPSK spectrum is equivalent to that of the baseband signal, although it has been shifted (minus side included) to the carrier frequency. The bandwidth of BPSK is therefore twice that of the baseband signal. When inserting a, the BPSK bandwidth for the symbol rate r (=/T) and rate is (+ )r. Demodulation by coherent detection simply reverses the process of modulation, as shown in Figure 5. The carrier circuit removes the modulated component and noise component from the received signal and recovers the carrier. The system then multiplies the received signal by this carrier to obtain the baseband signal, which is then input to a clock circuit to recover the same clock as that on the modulator side. With this clock, the system samples the baseband signal, decides whether the symbols are or, and restores the digital signal. On the other hand, demodulation by incoherent detection treats the received signal delayed by one symbol as the reference phase and multiplies the received signal by Broadcast Technology no.4, Spring 23 C NHK STRL 3
5 Baseband signal T t received signal data output Carrier t carrier clock Figure 5: BPSK demodulation by coherent detection PSK modulated wave information - Figure 2: BPSK modulated waveform baseband signal T: symbol period BPSK signal cos ( t) carrier Figure 3: BPSK modulation t received signal symbol delay clock Figure 6: BPSK demodulation by incoherent detection data output - -/2T /2T BER PSD [db] fc-4/t fc-3/t fc-2/t fc-/t fc fc+/t fc+2/t fc+3/t fc+4/t Figure 4: BPSK spectrum frequency C/N (db) Figure 7: BPSK bit error rate (coherent detection; the noise bandwidth is the Nyquist bandwidth) it to obtain the baseband signal, as shown in Figure 6. Incoherent detection is frequently used in terrestrial mobile transmissions since large fluctuations in amplitude due to fading effects make it difficult to recover the carrier. Here, however, because the signal itself, which includes noise and distortion, is used as the reference phase in incoherent detection, the bit error characteristics are worse than those of coherent detection. In addition, as the information is transmitted as a phase difference with respect to the previous symbol, differential conversion of code must be performed on the transmit side before modulation. BPSK symbol error rate assuming coherent detection of a BPSK signal to which noise has been added to the transmission path can expressed using Eq. (3), since the amplitude probability for the demodulated signal follows the Gaussian distribution shown in Figure 5. Since signal power C=A 2 /2 and noise power N= above equation can be rewritten as (7), the Because one bit corresponds to one symbol in BPSK, the above symbol error rate is the same as the bit error rate P b. This is shown in Figure 7. The CN ratio specifies the noise bandwidth, which is usually taken to be the Nyquist bandwidth. The noise bandwidth of a signal with symbol rate r (symbol/sec) is r (Hz). 2.2 QPSK (Quadrature Phase Shift Keying) The QPSK system uses carrier phases at 9-degree intervals to send two bits of information per symbol, and for this reason, it is sometimes called 4-phase PSK. It is very (8) 4 Broadcast Technology no.4, Spring 23 C NHK STRL
6 Lecture efficient in terms of required bandwidth and power and is robust against non-linear distortion on the transmission path. The QPSK system has consequently found wide use in satellite communications in which the CN ratio of the received signal is small. The configuration of the QPSK modulator is shown in Figure 8. The modulator performs serial-parallel conversion of the input signal, divides the resulting signal into I and Q signals, and performs BPSK modulation on both of the and orthogonal carriers. The system then combines these two modulated signals and outputs a QPSK modulated wave. Because QPSK combines the BPSK of two orthogonal carriers, the shape of its spectrum will be the same as that of BPSK (Figure 4), provided that the symbol rate is the same as BPSK. However, as QPSK transmits two bits of information for every symbol, it can transmit twice the amount of information (double the bit rate) of BPSK for the same bandwidth. A received signal A (a) Gray code A (b) Natural binary code Figure 9: QPSK gray-code-assignment constellation carrier clock data output P/S Bit stream B(t) I(t) S/P level convert - QPSK Figure 2: QPSK demodulation by coherent detection Q(t) level convert B(t) T T: symbol duration a b c d e received signal symbol delay clock data output P/S I(t) Q(t) a b c d e serial to parallel conversion Figure 8: Configuration of the QPSK modulator A phase map (constellation) in which the horizontal and vertical axes correspond to I and Q signals, respectively, is normally used in digital modulation to represent the relationship between bits transmitted in a symbol and the modulated level or phase. A QPSK constellation is shown in Figure 9. Symbol errors (code errors) occur when noise or distortion cause the signal to enter another quadrant of the phase plane. Symbol errors caused by Gaussian noise can be mostly regarded as errors involving adjacent signal areas. For this reason, multi-dimensional modulations like QPSK employ gray code assignment, whereby adjacent signal points on the phase plane each differ by one bit. In this way, the bit error can be minimized for the symbol error. As in the case of BPSK, QPSK demodulation can be performed via either coherent detection (Figure 2), which Figure 2: QPSK demodulation by incoherent detection recovers the carrier in the received signal, or incoherent detection (Figure 2), which does not require carrier. Denoting the amplitude and phase of the modulated signal by A(t) and (t), respectively, the transmit signal s(t) is given as follows. For BPSK,, while for QPSK,. In addition, noise added to the transmit signal is expressed as bandpass noise in the following way. () In coherent detection, the received signal is detected by using the recovered carrier at the receiver, and the I-axis r I (t) becomes as follows. (9) Broadcast Technology no.4, Spring 23 C NHK STRL 5
7 Next, with respect to a sample of symbol, r I (t) takes on the following form. for each (8) () The received signal is also detected by using the recovered carrier, and the Q-axis r Q (t) becomes as follows. The phase difference for each symbol on the I-axis is thus demodulated as information. Incoherent detection of the orthogonal axis (Q-axis) in an orthogonal modulation system such as QPSK results in the following expression for r Q (t), after shifting the phase of the signal delayed by one symbol by /2 and multiplying the result by the current signal. (9) After passing the above through an, we get Then, with respect to a sample of symbol, r Q (t) becomes. (2) for each (2) (2) After coherent detection, the I-axis and Q-axis signals, r I (t) and r Q (t), are passed through low-pass s (s) to generate baseband signals only, and the transmitted amplitude and phase, A(t) and (t), are then recovered from the post- r I (t) and r Q (t). (3) (4) In incoherent detection, the received signal delayed by one symbol is multiplied by the current signal, and the I- axis signal r I (t) becomes as follows. If we extract only the signal component here, we get (5) The phase difference for each symbol on the Q-axis is thus demodulated as information. We next consider the QPSK symbol error rate and bit error rate. For coherent detection, QPSK can be viewed as BPSK performed independently on the orthogonal I and Q signals. The QPSK symbol error rate P QPSK is expressed as follows, where the error rates of the I and Q signals are denoted by P I and P Q. (22) Since P I and P Q are each the same as the BPSK symbol error rate P BPSK, the above equation can be rewritten using Eq. (7). (23) Expressing the above in terms of the CN ratio, we get Eq. (24), considering that (from Figure 9). (24) (6) Then, after passing the above through an and extracting only the baseband component, r I (t) can be approximated as Now let us consider the QPSK bit error rate P b-qpsk. In the case of gray code assignment, the st and 2nd terms of Eq. (2) correspond to -bit error, while the 3rd term corresponds to 2-bit error. Therefore by multiplying the st, 2nd, and 3rd terms by /2, /2, and 2/2, respectively, we get the following expression for P b-qpsk. (7) 6 Broadcast Technology no.4, Spring 23 C NHK STRL
8 Lecture bit stream 2bit S/P 4 level level convert 6QAM (25) In other words, for a bit error rate equal to that of BPSK, the CN ratio of QPSK is larger by 3 db. However, compared with BPSK at the same bit rate, the symbol rate of QPSK is /2 that of BPSK, which means that transmission becomes possible at /2 the bandwidth. As a result, the signal power C required to obtain a bit error rate identical to that of BPSK is the same power as in BPSK. The bit error rate of QPSK with respect to the CN ratio is shown in Figure 22. 2bit level convert 4 level Figure 23: 6QAM modulator configuration Q I QAM -4 BER BPSK QPSK Figure 24: 6QAM constellation (compared with that of BPSK) is needed to obtain an equivalent error rate. The bit error rate of 6QAM coherent detection is C/N (db) Figure 22: QPSK bit error rate (coherent detection; the noise bandwidth is the Nyquist bandwidth) 2.3 QAM Reduction of bit rate by using source coding and band compression by using a modulation system are useful when transmitting digital signals over limited bands. In general, the case whereby a signal takes on four or more points of a constellation is called multi-dimensional modulation. A digital modulation that transmits M bits per symbol is called a 2 M -dimensional modulation (for PSK, this becomes 2 M -phase PSK). The signal obtained by performing orthogonal modulation on two multi-dimensional ASKs is called Quadrature Amplitude Modulation (QAM). The configuration of a 6QAM modulation circuit is shown in Figure 23. (26) Increasing the number of levels on each axis results in higher multi-dimensional modulations such as 64QAM and 256QAM. While frequency-usage efficiency improves with level, a higher receive power is needed to obtain a given bit error rate. The following expressions give the bit error rates for 64QAM and 256QAM. : 64QAM (27) : 256QAM (28) (Shunji Nakahara) The 6QAM modulation system can transmit four bits of information per symbol. As can be seen from the constellation in Figure 24, however, the distance between each code is small, which means that a large signal power Broadcast Technology no.4, Spring 23 C NHK STRL 7
Digital Modulation. David Tipper. Department of Information Science and Telecommunications University of Pittsburgh. Typical Communication System
Digital Modulation David Tipper Associate Professor Department of Information Science and Telecommunications University of Pittsburgh http://www.tele.pitt.edu/tipper.html Typical Communication System Source
Chap#5 (Data communication)
Chap#5 (Data communication) Q#1: Define analog transmission. Normally, analog transmission refers to the transmission of analog signals using a band-pass channel. Baseband digital or analog signals are
Lezione 6 Communications Blockset
Corso di Tecniche CAD per le Telecomunicazioni A.A. 2007-2008 Lezione 6 Communications Blockset Ing. Marco GALEAZZI 1 What Is Communications Blockset? Communications Blockset extends Simulink with a comprehensive
Department of Electrical and Computer Engineering Ben-Gurion University of the Negev. LAB 1 - Introduction to USRP
Department of Electrical and Computer Engineering Ben-Gurion University of the Negev LAB 1 - Introduction to USRP - 1-1 Introduction In this lab you will use software reconfigurable RF hardware from National
Implementation of Digital Signal Processing: Some Background on GFSK Modulation
Implementation of Digital Signal Processing: Some Background on GFSK Modulation Sabih H. Gerez University of Twente, Department of Electrical Engineering s.h.gerez@utwente.nl Version 4 (February 7, 2013)
Appendix D Digital Modulation and GMSK
D1 Appendix D Digital Modulation and GMSK A brief introduction to digital modulation schemes is given, showing the logical development of GMSK from simpler schemes. GMSK is of interest since it is used
How To Encode Data From A Signal To A Signal (Wired) To A Bitcode (Wired Or Coaxial)
Physical Layer Part 2 Data Encoding Techniques Networks: Data Encoding 1 Analog and Digital Transmissions Figure 2-23.The use of both analog and digital transmissions for a computer to computer call. Conversion
TCOM 370 NOTES 99-4 BANDWIDTH, FREQUENCY RESPONSE, AND CAPACITY OF COMMUNICATION LINKS
TCOM 370 NOTES 99-4 BANDWIDTH, FREQUENCY RESPONSE, AND CAPACITY OF COMMUNICATION LINKS 1. Bandwidth: The bandwidth of a communication link, or in general any system, was loosely defined as the width of
What s The Difference Between Bit Rate And Baud Rate?
What s The Difference Between Bit Rate And Baud Rate? Apr. 27, 2012 Lou Frenzel Electronic Design Serial-data speed is usually stated in terms of bit rate. However, another oftquoted measure of speed is
T = 1 f. Phase. Measure of relative position in time within a single period of a signal For a periodic signal f(t), phase is fractional part t p
Data Transmission Concepts and terminology Transmission terminology Transmission from transmitter to receiver goes over some transmission medium using electromagnetic waves Guided media. Waves are guided
Voice---is analog in character and moves in the form of waves. 3-important wave-characteristics:
Voice Transmission --Basic Concepts-- Voice---is analog in character and moves in the form of waves. 3-important wave-characteristics: Amplitude Frequency Phase Voice Digitization in the POTS Traditional
Sampling Theorem Notes. Recall: That a time sampled signal is like taking a snap shot or picture of signal periodically.
Sampling Theorem We will show that a band limited signal can be reconstructed exactly from its discrete time samples. Recall: That a time sampled signal is like taking a snap shot or picture of signal
Digital Transmission (Line Coding)
Digital Transmission (Line Coding) Pulse Transmission Source Multiplexer Line Coder Line Coding: Output of the multiplexer (TDM) is coded into electrical pulses or waveforms for the purpose of transmission
Digital Baseband Modulation
Digital Baseband Modulation Later Outline Baseband & Bandpass Waveforms Baseband & Bandpass Waveforms, Modulation A Communication System Dig. Baseband Modulators (Line Coders) Sequence of bits are modulated
Implementing Digital Wireless Systems. And an FCC update
Implementing Digital Wireless Systems And an FCC update Spectrum Repacking Here We Go Again: The FCC is reallocating 600 MHz Frequencies for Wireless Mics 30-45 MHz (8-m HF) 174-250 MHz (VHF) 450-960 MHz
Large-Capacity Optical Transmission Technologies Supporting the Optical Submarine Cable System
Large-Capacity Optical Transmission Technologies Supporting the Optical Submarine Cable System INOUE Takanori Abstract As one of the foundations of the global network, the submarine cable system is required
INTRODUCTION TO COMMUNICATION SYSTEMS AND TRANSMISSION MEDIA
COMM.ENG INTRODUCTION TO COMMUNICATION SYSTEMS AND TRANSMISSION MEDIA 9/6/2014 LECTURES 1 Objectives To give a background on Communication system components and channels (media) A distinction between analogue
AN INTRODUCTION TO DIGITAL MODULATION
AN INTRODUCTION TO DIGITAL MODULATION This article provides readers a simple overview of the various popular methods used in modulating a digital signal. The relative merits of each of these modulation
Public Switched Telephone System
Public Switched Telephone System Structure of the Telephone System The Local Loop: Modems, ADSL Structure of the Telephone System (a) Fully-interconnected network. (b) Centralized switch. (c) Two-level
Lecture 3: Signaling and Clock Recovery. CSE 123: Computer Networks Stefan Savage
Lecture 3: Signaling and Clock Recovery CSE 123: Computer Networks Stefan Savage Last time Protocols and layering Application Presentation Session Transport Network Datalink Physical Application Transport
MSB MODULATION DOUBLES CABLE TV CAPACITY Harold R. Walker and Bohdan Stryzak Pegasus Data Systems ( 5/12/06) pegasusdat@aol.com
MSB MODULATION DOUBLES CABLE TV CAPACITY Harold R. Walker and Bohdan Stryzak Pegasus Data Systems ( 5/12/06) pegasusdat@aol.com Abstract: Ultra Narrow Band Modulation ( Minimum Sideband Modulation ) makes
5 Signal Design for Bandlimited Channels
225 5 Signal Design for Bandlimited Channels So far, we have not imposed any bandwidth constraints on the transmitted passband signal, or equivalently, on the transmitted baseband signal s b (t) I[k]g
1 Multi-channel frequency division multiplex frequency modulation (FDM-FM) emissions
Rec. ITU-R SM.853-1 1 RECOMMENDATION ITU-R SM.853-1 NECESSARY BANDWIDTH (Question ITU-R 77/1) Rec. ITU-R SM.853-1 (1992-1997) The ITU Radiocommunication Assembly, considering a) that the concept of necessary
RECOMMENDATION ITU-R BO.786 *
Rec. ITU-R BO.786 RECOMMENDATION ITU-R BO.786 * MUSE ** system for HDTV broadcasting-satellite services (Question ITU-R /) (992) The ITU Radiocommunication Assembly, considering a) that the MUSE system
Clock Recovery in Serial-Data Systems Ransom Stephens, Ph.D.
Clock Recovery in Serial-Data Systems Ransom Stephens, Ph.D. Abstract: The definition of a bit period, or unit interval, is much more complicated than it looks. If it were just the reciprocal of the data
4 Digital Video Signal According to ITU-BT.R.601 (CCIR 601) 43
Table of Contents 1 Introduction 1 2 Analog Television 7 3 The MPEG Data Stream 11 3.1 The Packetized Elementary Stream (PES) 13 3.2 The MPEG-2 Transport Stream Packet.. 17 3.3 Information for the Receiver
PCM Encoding and Decoding:
PCM Encoding and Decoding: Aim: Introduction to PCM encoding and decoding. Introduction: PCM Encoding: The input to the PCM ENCODER module is an analog message. This must be constrained to a defined bandwidth
QAM Demodulation. Performance Conclusion. o o o o o. (Nyquist shaping, Clock & Carrier Recovery, AGC, Adaptive Equaliser) o o. Wireless Communications
0 QAM Demodulation o o o o o Application area What is QAM? What are QAM Demodulation Functions? General block diagram of QAM demodulator Explanation of the main function (Nyquist shaping, Clock & Carrier
NRZ Bandwidth - HF Cutoff vs. SNR
Application Note: HFAN-09.0. Rev.2; 04/08 NRZ Bandwidth - HF Cutoff vs. SNR Functional Diagrams Pin Configurations appear at end of data sheet. Functional Diagrams continued at end of data sheet. UCSP
Physical Layer, Part 2 Digital Transmissions and Multiplexing
Physical Layer, Part 2 Digital Transmissions and Multiplexing These slides are created by Dr. Yih Huang of George Mason University. Students registered in Dr. Huang's courses at GMU can make a single machine-readable
Broadband Networks. Prof. Dr. Abhay Karandikar. Electrical Engineering Department. Indian Institute of Technology, Bombay. Lecture - 29.
Broadband Networks Prof. Dr. Abhay Karandikar Electrical Engineering Department Indian Institute of Technology, Bombay Lecture - 29 Voice over IP So, today we will discuss about voice over IP and internet
Software Defined Radio
Software Defined Radio GNU Radio and the USRP Overview What is Software Defined Radio? Advantages of Software Defined Radio Traditional versus SDR Receivers SDR and the USRP Using GNU Radio Introduction
Data Transmission. Data Communications Model. CSE 3461 / 5461: Computer Networking & Internet Technologies. Presentation B
CSE 3461 / 5461: Computer Networking & Internet Technologies Data Transmission Presentation B Kannan Srinivasan 08/30/2012 Data Communications Model Figure 1.2 Studying Assignment: 3.1-3.4, 4.1 Presentation
Agilent Digital Modulation in Communications Systems An Introduction. Application Note 1298
Agilent Digital Modulation in Communications Systems An Introduction Application Note 1298 Introduction This application note introduces the concepts of digital modulation used in many communications systems
Example/ an analog signal f ( t) ) is sample by f s = 5000 Hz draw the sampling signal spectrum. Calculate min. sampling frequency.
1 2 3 4 Example/ an analog signal f ( t) = 1+ cos(4000πt ) is sample by f s = 5000 Hz draw the sampling signal spectrum. Calculate min. sampling frequency. Sol/ H(f) -7KHz -5KHz -3KHz -2KHz 0 2KHz 3KHz
Time and Frequency Domain Equalization
Time and Frequency Domain Equalization Presented By: Khaled Shawky Hassan Under Supervision of: Prof. Werner Henkel Introduction to Equalization Non-ideal analog-media such as telephone cables and radio
Introduction to Receivers
Introduction to Receivers Purpose: translate RF signals to baseband Shift frequency Amplify Filter Demodulate Why is this a challenge? Interference (selectivity, images and distortion) Large dynamic range
Mobile Communications Chapter 2: Wireless Transmission
Mobile Communications Chapter 2: Wireless Transmission Frequencies Signals Antennas Signal propagation Multiplexing Spread spectrum Modulation Cellular systems Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
PHASE ESTIMATION ALGORITHM FOR FREQUENCY HOPPED BINARY PSK AND DPSK WAVEFORMS WITH SMALL NUMBER OF REFERENCE SYMBOLS
PHASE ESTIMATION ALGORITHM FOR FREQUENCY HOPPED BINARY PSK AND DPSK WAVEFORMS WITH SMALL NUM OF REFERENCE SYMBOLS Benjamin R. Wiederholt The MITRE Corporation Bedford, MA and Mario A. Blanco The MITRE
HD Radio FM Transmission System Specifications Rev. F August 24, 2011
HD Radio FM Transmission System Specifications Rev. F August 24, 2011 SY_SSS_1026s TRADEMARKS HD Radio and the HD, HD Radio, and Arc logos are proprietary trademarks of ibiquity Digital Corporation. ibiquity,
1. (Ungraded) A noiseless 2-kHz channel is sampled every 5 ms. What is the maximum data rate?
Homework 2 Solution Guidelines CSC 401, Fall, 2011 1. (Ungraded) A noiseless 2-kHz channel is sampled every 5 ms. What is the maximum data rate? 1. In this problem, the channel being sampled gives us the
AN1200.04. Application Note: FCC Regulations for ISM Band Devices: 902-928 MHz. FCC Regulations for ISM Band Devices: 902-928 MHz
AN1200.04 Application Note: FCC Regulations for ISM Band Devices: Copyright Semtech 2006 1 of 15 www.semtech.com 1 Table of Contents 1 Table of Contents...2 1.1 Index of Figures...2 1.2 Index of Tables...2
EECC694 - Shaaban. Transmission Channel
The Physical Layer: Data Transmission Basics Encode data as energy at the data (information) source and transmit the encoded energy using transmitter hardware: Possible Energy Forms: Electrical, light,
Antennas & Propagation. CS 6710 Spring 2010 Rajmohan Rajaraman
Antennas & Propagation CS 6710 Spring 2010 Rajmohan Rajaraman Introduction An antenna is an electrical conductor or system of conductors o Transmission - radiates electromagnetic energy into space o Reception
Non-Data Aided Carrier Offset Compensation for SDR Implementation
Non-Data Aided Carrier Offset Compensation for SDR Implementation Anders Riis Jensen 1, Niels Terp Kjeldgaard Jørgensen 1 Kim Laugesen 1, Yannick Le Moullec 1,2 1 Department of Electronic Systems, 2 Center
How To Understand The Theory Of Time Division Duplexing
Multiple Access Techniques Dr. Francis LAU Dr. Francis CM Lau, Associate Professor, EIE, PolyU Content Introduction Frequency Division Multiple Access Time Division Multiple Access Code Division Multiple
RF Measurements Using a Modular Digitizer
RF Measurements Using a Modular Digitizer Modern modular digitizers, like the Spectrum M4i series PCIe digitizers, offer greater bandwidth and higher resolution at any given bandwidth than ever before.
DVB-T. The echo performance of. receivers. Theory of echo tolerance. Ranulph Poole BBC Research and Development
The echo performance of DVB-T Ranulph Poole BBC Research and Development receivers This article introduces a model to describe the way in which a single echo gives rise to an equivalent noise floor (ENF)
ELE745 Assignment and Lab Manual
ELE745 Assignment and Lab Manual August 22, 2010 CONTENTS 1. Assignment 1........................................ 1 1.1 Assignment 1 Problems................................ 1 1.2 Assignment 1 Solutions................................
DSAM Digital Quality Index (DQI) A New Technique for Assessing Downstream Digital Services
Application Note DSAM Digital Quality Index (DQI) A New Technique for Assessing Downstream Digital Services Overview As cable operators move to digital simulcast and all digital networks, the majority
ISDB-T T Transmission Technologies and Emergency Warning System
ISDB-T T Seminar ISDB-T T Transmission Technologies and Emergency Warning System 12 de Febrero 2008 Universidad Ricardo Palma, Lima, Perú DiBEG, JAPAN Hiroyuki FURUTA (NHK) Digital broadcasting experts
Clock Jitter Definitions and Measurement Methods
January 2014 Clock Jitter Definitions and Measurement Methods 1 Introduction Jitter is the timing variations of a set of signal edges from their ideal values. Jitters in clock signals are typically caused
Application Note Noise Frequently Asked Questions
: What is? is a random signal inherent in all physical components. It directly limits the detection and processing of all information. The common form of noise is white Gaussian due to the many random
ANALYZER BASICS WHAT IS AN FFT SPECTRUM ANALYZER? 2-1
WHAT IS AN FFT SPECTRUM ANALYZER? ANALYZER BASICS The SR760 FFT Spectrum Analyzer takes a time varying input signal, like you would see on an oscilloscope trace, and computes its frequency spectrum. Fourier's
Vector Signal Analyzer FSQ-K70
Product brochure Version 02.00 Vector Signal Analyzer FSQ-K70 July 2004 Universal demodulation, analysis and documentation of digital radio signals For all major mobile radio communication standards: GSM
Timing Errors and Jitter
Timing Errors and Jitter Background Mike Story In a sampled (digital) system, samples have to be accurate in level and time. The digital system uses the two bits of information the signal was this big
Duobinary Modulation For Optical Systems
Introduction Duobinary Modulation For Optical Systems Hari Shanar Inphi Corporation Optical systems by and large use NRZ modulation. While NRZ modulation is suitable for long haul systems in which the
Fundamentals of Satellite Communications Part 3
Fundamentals of Satellite Communications Part 3 Modulation Techniques used in Satellite Communication Howard Hausman December, 2009 Fundamentals of Satellite Communications Part 3 Modulation Techniques
Sistemi di Trasmissione Radio. Università di Pavia. Sistemi di Trasmissione Radio
Programma del corso Tecniche di trasmissione Modulazioni numeriche Sistemi ad allargameneto di banda Sistemi multi-tono Codifica di canale Codifica di sorgente (vocoder) Programma del corso Sistemi di
The front end of the receiver performs the frequency translation, channel selection and amplification of the signal.
Many receivers must be capable of handling a very wide range of signal powers at the input while still producing the correct output. This must be done in the presence of noise and interference which occasionally
Lecture 1: Introduction
Mobile Data Networks Lecturer: Victor O.K. Li EEE Department Room: CYC601D Tel.: 857 845 Email: vli@eee.hku.hk Course home page: http://www.eee.hku.hk/courses.msc/ 1 Lecture 1: Introduction Mobile data
Appendix C GSM System and Modulation Description
C1 Appendix C GSM System and Modulation Description C1. Parameters included in the modelling In the modelling the number of mobiles and their positioning with respect to the wired device needs to be taken
October 1, 2015. (Press release) Nippon Telegraph and Telephone Corporation
(Press release) October 1, 2015 Nippon Telegraph and Telephone Corporation High-density simultaneous compensation of distortion in wavelength-multiplexed signals using a time-reversal operation: World
Performance of Quasi-Constant Envelope Phase Modulation through Nonlinear Radio Channels
Performance of Quasi-Constant Envelope Phase Modulation through Nonlinear Radio Channels Qi Lu, Qingchong Liu Electrical and Systems Engineering Department Oakland University Rochester, MI 48309 USA E-mail:
A WEB BASED TRAINING MODULE FOR TEACHING DIGITAL COMMUNICATIONS
A WEB BASED TRAINING MODULE FOR TEACHING DIGITAL COMMUNICATIONS Ali Kara 1, Cihangir Erdem 1, Mehmet Efe Ozbek 1, Nergiz Cagiltay 2, Elif Aydin 1 (1) Department of Electrical and Electronics Engineering,
Solution. (Chapters 5-6-7-8) Dr. Hasan Qunoo. The Islamic University of Gaza. Faculty of Engineering. Computer Engineering Department
The Islamic University of Gaza Faculty of Engineering Computer Engineering Department Data Communications ECOM 4314 Solution (Chapters 5-6-7-8) Dr. Hasan Qunoo Eng. Wafaa Audah Eng. Waleed Mousa 1. A cable
CDMA TECHNOLOGY. Brief Working of CDMA
CDMA TECHNOLOGY History of CDMA The Cellular Challenge The world's first cellular networks were introduced in the early 1980s, using analog radio transmission technologies such as AMPS (Advanced Mobile
All About Pulse Modulation How Ultra Narrow Band Modulation works Updated 12/15//10
All About Pulse Modulation How Ultra Narrow Band Modulation works Updated 12/15//10 Pulse modulation is well known in many forms. In communications it first appeared as Morse Code, otherwise known as ON/OFF
RADIO FREQUENCY INTERFERENCE AND CAPACITY REDUCTION IN DSL
RADIO FREQUENCY INTERFERENCE AND CAPACITY REDUCTION IN DSL Padmabala Venugopal, Michael J. Carter*, Scott A. Valcourt, InterOperability Laboratory, Technology Drive Suite, University of New Hampshire,
The Effect of Network Cabling on Bit Error Rate Performance. By Paul Kish NORDX/CDT
The Effect of Network Cabling on Bit Error Rate Performance By Paul Kish NORDX/CDT Table of Contents Introduction... 2 Probability of Causing Errors... 3 Noise Sources Contributing to Errors... 4 Bit Error
Jitter Measurements in Serial Data Signals
Jitter Measurements in Serial Data Signals Michael Schnecker, Product Manager LeCroy Corporation Introduction The increasing speed of serial data transmission systems places greater importance on measuring
(Refer Slide Time: 2:10)
Data Communications Prof. A. Pal Department of Computer Science & Engineering Indian Institute of Technology, Kharagpur Lecture-12 Multiplexer Applications-1 Hello and welcome to today s lecture on multiplexer
DVB-T BER MEASUREMENTS IN THE PRESENCE OF ADJACENT CHANNEL AND CO-CHANNEL ANALOGUE TELEVISION INTERFERENCE
DVB-T MEASUREMENTS IN THE PRESENCE OF ADJACENT CHANNEL AND CO-CHANNEL ANALOGUE TELEVISION INTERFERENCE M. Mª Vélez (jtpveelm@bi.ehu.es), P. Angueira, D. de la Vega, A. Arrinda, J. L. Ordiales UNIVERSITY
Digital Fundamentals
Digital Fundamentals Tenth Edition Floyd Chapter 1 2009 Pearson Education, Upper 2008 Pearson Saddle River, Education NJ 07458. All Rights Reserved Analog Quantities Most natural quantities that we see
TCOM 370 NOTES 99-6 VOICE DIGITIZATION AND VOICE/DATA INTEGRATION
TCOM 370 NOTES 99-6 VOICE DIGITIZATION AND VOICE/DATA INTEGRATION (Please read appropriate parts of Section 2.5.2 in book) 1. VOICE DIGITIZATION IN THE PSTN The frequencies contained in telephone-quality
Probability and Random Variables. Generation of random variables (r.v.)
Probability and Random Variables Method for generating random variables with a specified probability distribution function. Gaussian And Markov Processes Characterization of Stationary Random Process Linearly
1 Lecture Notes 1 Interference Limited System, Cellular. Systems Introduction, Power and Path Loss
ECE 5325/6325: Wireless Communication Systems Lecture Notes, Spring 2015 1 Lecture Notes 1 Interference Limited System, Cellular Systems Introduction, Power and Path Loss Reading: Mol 1, 2, 3.3, Patwari
ISI Mitigation in Image Data for Wireless Wideband Communications Receivers using Adjustment of Estimated Flat Fading Errors
International Journal of Engineering and Management Research, Volume-3, Issue-3, June 2013 ISSN No.: 2250-0758 Pages: 24-29 www.ijemr.net ISI Mitigation in Image Data for Wireless Wideband Communications
Analog vs. Digital Transmission
Analog vs. Digital Transmission Compare at two levels: 1. Data continuous (audio) vs. discrete (text) 2. Signaling continuously varying electromagnetic wave vs. sequence of voltage pulses. Also Transmission
Introduction to FM-Stereo-RDS Modulation
Introduction to FM-Stereo-RDS Modulation Ge, Liang Tan, EK Kelly, Joe Verigy, China Verigy, Singapore Verigy US 1. Introduction Frequency modulation (FM) has a long history of its application and is widely
Voice services over Adaptive Multi-user Orthogonal Sub channels An Insight
TEC Voice services over Adaptive Multi-user Orthogonal Sub channels An Insight HP 4/15/2013 A powerful software upgrade leverages quaternary modulation and MIMO techniques to improve network efficiency
Adjacent Channel Interference. Adaptive Modulation and Coding. Advanced Mobile Phone System. Automatic Repeat Request. Additive White Gaussian Noise
Apéndice A. Lista de s ACI AM AMC AMPS ARQ AWGN BB BER BPSK BPF BW CCK CD CDMA CDPD COFDM CRL CSI CWTS Adjacent Channel Interference Amplitude Modulation Adaptive Modulation and Coding Advanced Mobile
RESULTS OF TESTS WITH DOMESTIC RECEIVER IC S FOR DVB-T. C.R. Nokes BBC R&D, UK ABSTRACT
RESULTS OF TESTS WITH DOMESTIC RECEIVER IC S FOR DVB-T C.R. Nokes BBC R&D, UK ABSTRACT Digital terrestrial television services using the DVB-T standard will be launched later this year in the UK, followed
INTERNATIONAL TELECOMMUNICATION UNION
INTERNATIONAL TELECOMMUNICATION UNION )454 6 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU $!4! #/--5.)#!4)/. /6%2 4(% 4%,%0(/.%.%47/2+ ")43 0%2 3%#/.$ $50,%8 -/$%- 34!.$!2$):%$ &/2 53% ). 4(% '%.%2!,
APPLICATION NOTE. RF System Architecture Considerations ATAN0014. Description
APPLICATION NOTE RF System Architecture Considerations ATAN0014 Description Highly integrated and advanced radio designs available today, such as the Atmel ATA5830 transceiver and Atmel ATA5780 receiver,
Experiment 3: Double Sideband Modulation (DSB)
Experiment 3: Double Sideband Modulation (DSB) This experiment examines the characteristics of the double-sideband (DSB) linear modulation process. The demodulation is performed coherently and its strict
Objectives. Lecture 4. How do computers communicate? How do computers communicate? Local asynchronous communication. How do computers communicate?
Lecture 4 Continuation of transmission basics Chapter 3, pages 75-96 Dave Novak School of Business University of Vermont Objectives Line coding Modulation AM, FM, Phase Shift Multiplexing FDM, TDM, WDM
University of Manchester School of Computer Science CS3282: Digital Communications '06 Section 9: Multi-level digital modulation & demodulation.
CS3282 Digital Comms 9.1 2 May 06 / BMGC University of Manchester School of Computer Science CS3282: Digital Communications '06 Section 9: Multi-level digital modulation & demodulation. 9.1. ntroduction:
Lab 5 Getting started with analog-digital conversion
Lab 5 Getting started with analog-digital conversion Achievements in this experiment Practical knowledge of coding of an analog signal into a train of digital codewords in binary format using pulse code
CS423: Lectures 2-4, Physical Layer. George Varghese. April 16, 2008
CS423: Lectures 2-4, Physical Layer George Varghese April 16, 2008 What does the Physical Layer Do? bits SENDER PHYSICAL LAYER RECEIVER 1 RECEIVER 1 RECEIVER 1 A possibly faulty, single-hop, bit pipe that
A Performance Study of Wireless Broadband Access (WiMAX)
A Performance Study of Wireless Broadband Access (WiMAX) Maan A. S. Al-Adwany Department of Computer & Information Engineering, College of Electronics Engineering University of Mosul Mosul, Iraq maanaladwany@yahoo.com
Symbol interval T=1/(2B); symbol rate = 1/T=2B transmissions/sec (The transmitted baseband signal is assumed to be real here) Noise power = (N_0/2)(2B)=N_0B \Gamma is no smaller than 1 The encoded PAM
Log-Likelihood Ratio-based Relay Selection Algorithm in Wireless Network
Recent Advances in Electrical Engineering and Electronic Devices Log-Likelihood Ratio-based Relay Selection Algorithm in Wireless Network Ahmed El-Mahdy and Ahmed Walid Faculty of Information Engineering
DT3: RF On/Off Remote Control Technology. Rodney Singleton Joe Larsen Luis Garcia Rafael Ocampo Mike Moulton Eric Hatch
DT3: RF On/Off Remote Control Technology Rodney Singleton Joe Larsen Luis Garcia Rafael Ocampo Mike Moulton Eric Hatch Agenda Radio Frequency Overview Frequency Selection Signals Methods Modulation Methods
Computer Networks and Internets, 5e Chapter 6 Information Sources and Signals. Introduction
Computer Networks and Internets, 5e Chapter 6 Information Sources and Signals Modified from the lecture slides of Lami Kaya (LKaya@ieee.org) for use CECS 474, Fall 2008. 2009 Pearson Education Inc., Upper
Evolution from Voiceband to Broadband Internet Access
Evolution from Voiceband to Broadband Internet Access Murtaza Ali DSPS R&D Center Texas Instruments Abstract With the growth of Internet, demand for high bit rate Internet access is growing. Even though
On Cables and Connections A discussion by Dr. J. Kramer
KRAMER ELECTRONICS LTD. On Cables and Connections A discussion by Dr. J. Kramer We are frequently asked - "what length of cable can I use for a specific application?" Seemingly a simple question, but the
MATRIX TECHNICAL NOTES
200 WOOD AVENUE, MIDDLESEX, NJ 08846 PHONE (732) 469-9510 FAX (732) 469-0418 MATRIX TECHNICAL NOTES MTN-107 TEST SETUP FOR THE MEASUREMENT OF X-MOD, CTB, AND CSO USING A MEAN SQUARE CIRCUIT AS A DETECTOR
FCC CABLE RULES. 76.605 Technical Standards
CODE OF FEDERAL REGULATIONS TITLE 47 -- TELECOMMUNICATION CHAPTER I -- FEDERAL COMMUNICATIONS COMMISSION SUBCHAPTER C -- BROADCAST RADIO SERVICES PART 76--CABLE TELEVISION SERVICE 76.605 Technical Standards
Module: Digital Communications. Experiment 784. DSL Transmission. Institut für Nachrichtentechnik E-8 Technische Universität Hamburg-Harburg
Module: Digital Communications Experiment 784 DSL Transmission Institut für Nachrichtentechnik E-8 Technische Universität Hamburg-Harburg ii Table of Contents Introduction... 1 1 The DSL System... 2 1.1