DOCSLIB.ORG

A Solid State VHF Single Sideband Transmitter

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Solid State VHF Single Sideband Transmitter University of Central Florida STARS Retrospective Theses and Dissertations 1973 A Solid State VHF Single Sideband Transmitter Ermi Roos University of Central Florida Part of the Engineering Commons Find similar works at: https://stars.library.ucf.edu/rtd University of Central Florida Libraries http://library.ucf.edu This Masters Thesis (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Roos, Ermi, "A Solid State VHF Single Sideband Transmitter" (1973). Retrospective Theses and Dissertations. 71. https://stars.library.ucf.edu/rtd/71 A SOLID STATE VHF SINGLE SIDEBAND TRANSMI TTER Emf Roos B.S.E.E., Newark College of Engineering, 1966 Submitted in partial fulfillment of the requirements 4 for the degree of Master of Science in Engineering in the Graduate Studies Program of Florida Technological University, 1973 .Orlando, Florida TAB= OF CONTENTS Page 1.0 INTRODUCTION 1 2.0 PRINCIPLES OF ENVELOPE ELIMINATION AND RESTORATION SINGLE SIDEBAND 3.0 CIRCUIT DESCRIPTf ON 5.0 CONCLUSIONS APPENDIX A EFFECT OF FREQUENCY DIVISION OF THE - '. PKASE MUDUWITTON COMPONENT APPE3DIX B - EFFECT OF PHASE SHIFT IN THE ENVELOPE . FLIMINATION AND RESTOR4)TION SYSTEM I ,I APPENDIX C - LINEAX AMPLIFICATION WITH CLASS C BIBLIOGRAPHY LIST OF FIGURES Page Figure 1 Voltage and Current Waveforms of a Class C Amplifier Figure 2 Voltage and Current Waveforms of a Claas A Amplifier Figure 3 Basic Envelope Elimination and $&+&- , .:;;?$ &&&@lp-a;.%... --g Res'boration System Figure 4 Proposed Solid State VHF SSB Transmitter Figure 5 The Mef nzer Method Figure 6 SSB Generator Figure 7 Signal Processor Figure 8 Frequency Converter Figure 9 Modulator Figure 10 Transmitter vi Page Figure 11 Power Supply 44 Figure 12 Balanced Modulator Output Test Setup Figure 13 Frequency Spectrum of Balanoed Modula$or -. Figure 14 Frequency Response Test Setup Figure 15 ~odulatorFrequency Response Figure 16 Transmitter AM Operation Test Setup Figure 17 Transmitter Envelope for Single Tone Modulation Figure 18 SSB Generator Output Test Setup Figure 19 Frequency Spectrum of SSB Generator Output Figure 20 Frequency Spectrum of Limiter Output vii Page Figure 21 Frequency Conver"t;er Output Test Setup Figure 22 Frequency Spectrum of Transmitter output Figure A1 Phasor Representation of AM ( Single-Tone ~odulation) Figure A2 Phasor Representation of DSB-SC (single-Tone ~odulation) Figure A3 Phasor Representation of SSB and mPseudo-Carrierw (Two-Tone Modulation) Figure A4 Phase Modulation Component of SSB (Two-Tone ~odulation) Figure A5 Phase Shift of SSB Phase ModuLation Component ( Two-Tone adulation) Figure ~6 Frequency Spectrum of the Phase Modulation Component viii Page Figure A7 waveform of the Frequency Divider Output Figure A8 Frequency Spectrum of Frequency Divider Output Figure B1 Multiplication of RF and AF Components 1.0 INTRODUCTION Single sideband (SSB) is a very old method of radio co-ni- caei6nsand several decades of experimentation have resulted in a standard reliable method of generating SSB power. This is the cLas~ical~~filte~*method where a balanced modulator suppresses the AM carrier, a bandpass filter selects the de- sired sideband, a mixer selects the desired transmitter fre- quency, and a linear amplifier devezops the required trans- The earliest transmitters glade in , - mitter power. SSB were \ this manner, as well as the most recent one@. This method of generating SSB has the undesired feature that high level sideband power cannot be generated directly, such as with AM, but must be developed with successive linear anplification. Linear amplifiers have low efficiency, are very susceptible to self-oscillation, and tend to generate intermodulation products, If transistors are used, the de- vices tend to go into "second breakdownw when they are for- ward biased sufficiently for good linearity. The *'second breakdownw effect becomes mcm severe with increasing fre-' quency, making the design of transistorized VHF SSB trans- mitters difficult. A few methods of generating SS$ power directly. have been developed, but none :.ha.sbeen very widely used. .One is the "phasingM method, where SSB power may be generaeed in a fin- \I al balanced modulator, Such a scheme would be practical on- I I ly in a single frequency transmitter, because the carrier phase shift network must be set as close to 90 degrees as possible, and networks that would track the carrier frequency would be difficult to adjust, Practical @@phasingMtrans- mitters, in fact, use mixers and linear amplifiers. The phas- ing circuit is simply used as a low-level single frequency SSB source. It is used as a means of eliminating the need * for a bandpass filter with a high skirt factor, which was dif- ficult and expensive to make years ago. An interesting, but almost unknown, method of generating dir- ect ssB was developed by 0 .G. Villard in 1948, Villard took advantage of the fact that a narrowband phase modulated signal has sidebands that are identical to those of AM, but the carrier signal is 90 degrees out of phase with that of AM. By mixing a signal that is 90 degrees out of phase with the audio signal , with a signal that is phase modulated by the audio signal, one of the sidebands is suppressed. Unfortu- nately, the carrier remains; and one of the reasons for using SSB is to eliminate the need for generating carrier power. What is unique about Villardts method is that the mixing my be '0. G. Villard., nComposite Amplitude and Phase Modulation, E-lectronics, November, 1948, pp, 86-89. done by amplitude modulating a class C amplifier, The transmitter described in this paper uses a similar method of generating SSB power, In 1952, Leonard R. Kahn wrote a paper describing the prin- ciples of amplifying SSB by envelope elimination and restor- ation, With this scheme, - a low-level SSB signal is infin- itely limited, leaving only a phase modulated signal, The phase modulated signal is amplified to a high level wlth class C amplifiers. A portion of the original SSB signal is en- velope detected, and the detector output is applied to an AM modulator that modulates the last c1aas.C amplifier. The class C amplifier output is a reproduction of the original SSB signal. The object of this paper is to demonstrate that the Kahn meth- od provides a practical means of designing a solid-state VHF SSB transmitter, This method exchanges increased complexity in low-level circuits for increased efficiency and ease of design and adjustment of the final-power amplifier. Al- though Kahnos transmitter has not been popular in the past, it will be argued here that the relative cost between low- - '~eonard R . Kahn, "Single Sideband Transmission by Envelope Elimination and Restoration," Proceedings of the I,R,E., July, 1952, pp, 803-806. 4 level integrated circuits and high-level RF transistors jus- tifies the use of complex low-level circuits, and simple RF power circuits, The results of testing an actual envelope elimination and restoration transmitter will be described here. Since a standard VHF transmitter of comparable performance was not designed, striot comparisons between the two methods cannot be made. Nevertheless, the practicality of the envelope elimination and. restoration technique will be demonstrated. 2.0 PRINCIPLES OF ENVELOPE ELIMINATION AND RESTOMTION SINGLE SIDBAND 2.1 Basic Theory The generation of SSB power by envelope elimination and res- toration is based upon the fact that any continuous wave mod- ulated signal may be expressed as a product of the detected signal envelope and s phase modulation Component. be expressed by the equation below, Where E(t) is the envelope function,wb is the carrier fre- : quency, $(a) is the phase function, and cos [ + #(%)I is the carrier, or phase modulation component. By separat- .ing the envelope function from the phase modulation compon- ent, and amplif'ying the two signals separately, it is pos- sible to recombine the signals in a high power mixer,and re- produce the original composite signal, The phase modulation component in ~~uation1 may be isol- ated by multiplying f (t) by the inverse of the envelope function, which is ~(t)cos C kt + #(t)] E(t) In practice, multiplication by the inverse of the envelope component is accomplished with a zer~-croesing detector, or an infinite limiter. fpM(t). is amplified to the desired level' using class C awpUfters, and then multiplied by a. signal pro-. portional to the envelope function, E(%), to restore the 1 original signal, (1). E(C) is obtained by AM detecting the continuous-wave modulated signal. Multiplication of two signals -is usually done by the use of a balanoed moduit%tor, but, in this case, a standard AM mod- ulator is sufficient. This is because ~(t)contains a DC component that prevents negative excursions of ~(t),A class C amplifier, which is suitable for amplifying fpM(t ) , may then also be used for multiplying E(t) with fpM(t). Accurate restoration of the original signal depends upon correctly preserving the amplitude and time relationships of ~(t)and fpM(t). Any errors in either signal will cause distortion in the restored. signal, 2.2 Linear and Nonlinear RF Amplifiers If an RF signal has no time-varying envelope, it may be .amp- lified without distortion by either linear or nonlinear , amp- lifiers. This is because all of the distortion products pro- duced by nonlinearity will be centered around the harmonics of the carrier frequency, and they may easily be filtered out by conventional power amplifier tuned circuits. If a signal has an envelope, however, nonlinear amplifier gain will cause the envelope to amplitude modulate the desired signal, resulting in distortion products within the passband of the desired signal.
Load more

Recommended publications
  • UNIT V- SPREAD SPECTRUM MODULATION Introduction
    UNIT V- SPREAD SPECTRUM MODULATION Introduction: Initially developed for military applications during II world war, that was less sensitive to intentional interference or jamming by third parties. Spread spectrum technology has blossomed into one of the fundamental building blocks in current and next-generation wireless systems. Problem of radio transmission Narrow band can be wiped out due to interference. To disrupt the communication, the adversary needs to do two things, (a) to detect that a transmission is taking place and (b) to transmit a jamming signal which is designed to confuse the receiver. Solution A spread spectrum system is therefore designed to make these tasks as difficult as possible. Firstly, the transmitted signal should be difficult to detect by an adversary/jammer, i.e., the signal should have a low probability of intercept (LPI). Secondly, the signal should be difficult to disturb with a jamming signal, i.e., the transmitted signal should possess an anti-jamming (AJ) property Remedy spread the narrow band signal into a broad band to protect against interference In a digital communication system the primary resources are Bandwidth and Power. The study of digital communication system deals with efficient utilization of these two resources, but there are situations where it is necessary to sacrifice their efficient utilization in order to meet certain other design objectives. For example to provide a form of secure communication (i.e. the transmitted signal is not easily detected or recognized by unwanted listeners) the bandwidth of the transmitted signal is increased in excess of the minimum bandwidth necessary to transmit it.
    [Show full text]
  • CS647: Advanced Topics in Wireless Networks Basics
    CS647: Advanced Topics in Wireless Networks Basics of Wireless Transmission Part II Drs. Baruch Awerbuch & Amitabh Mishra Computer Science Department Johns Hopkins University CS 647 2.1 Antenna Gain For a circular reflector antenna G = η ( π D / λ )2 η = net efficiency (depends on the electric field distribution over the antenna aperture, losses such as ohmic heating , typically 0.55) D = diameter, thus, G = η (π D f /c )2, c = λ f (c is speed of light) Example: Antenna with diameter = 2 m, frequency = 6 GHz, wavelength = 0.05 m G = 39.4 dB Frequency = 14 GHz, same diameter, wavelength = 0.021 m G = 46.9 dB * Higher the frequency, higher the gain for the same size antenna CS 647 2.2 Path Loss (Free-space) Definition of path loss LP : Pt LP = , Pr Path Loss in Free-space: 2 2 Lf =(4π d/λ) = (4π f cd/c ) LPF (dB) = 32.45+ 20log10 fc (MHz) + 20log10 d(km), where fc is the carrier frequency This shows greater the fc, more is the loss. CS 647 2.3 Example of Path Loss (Free-space) Path Loss in Free-space 130 120 fc=150MHz (dB) f f =200MHz 110 c f =400MHz 100 c fc=800MHz 90 fc=1000MHz 80 Path Loss L fc=1500MHz 70 0 5 10 15 20 25 30 Distance d (km) CS 647 2.4 Land Propagation The received signal power: G G P P = t r t r L L is the propagation loss in the channel, i.e., L = LP LS LF Fast fading Slow fading (Shadowing) Path loss CS 647 2.5 Propagation Loss Fast Fading (Short-term fading) Slow Fading (Long-term fading) Signal Strength (dB) Path Loss Distance CS 647 2.6 Path Loss (Land Propagation) Simplest Formula: -α Lp = A d where A and
    [Show full text]
  • Demodulation of Chaos Phase Modulation Spread Spectrum Signals Using Machine Learning Methods and Its Evaluation for Underwater Acoustic Communication
    sensors Article Demodulation of Chaos Phase Modulation Spread Spectrum Signals Using Machine Learning Methods and Its Evaluation for Underwater Acoustic Communication Chao Li 1,2,*, Franck Marzani 3 and Fan Yang 3 1 State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China 2 University of Chinese Academy of Sciences, Beijing 100190, China 3 LE2I EA7508, Université Bourgogne Franche-Comté, 21078 Dijon, France; [email protected] (F.M.); [email protected] (F.Y.) * Correspondence: [email protected] Received: 25 September 2018; Accepted: 28 November 2018; Published: 1 December 2018 Abstract: The chaos phase modulation sequences consist of complex sequences with a constant envelope, which has recently been used for direct-sequence spread spectrum underwater acoustic communication. It is considered an ideal spreading code for its benefits in terms of large code resource quantity, nice correlation characteristics and high security. However, demodulating this underwater communication signal is a challenging job due to complex underwater environments. This paper addresses this problem as a target classification task and conceives a machine learning-based demodulation scheme. The proposed solution is implemented and optimized on a multi-core center processing unit (CPU) platform, then evaluated with replay simulation datasets. In the experiments, time variation, multi-path effect, propagation loss and random noise were considered as distortions. According to the results, compared to the reference algorithms, our method has greater reliability with better temporal efficiency performance. Keywords: underwater acoustic communication; direct sequence spread spectrum; chaos phase modulation sequence; partial least square regression; machine learning 1. Introduction The underwater acoustic communication has always been a crucial research topic [1–6].
    [Show full text]
  • Continuous Phase Modulation with Faster-Than-Nyquist Signaling for Channels with 1-Bit Quantization and Oversampling at the Receiver Rodrigo R
    1 Continuous Phase Modulation With Faster-than-Nyquist Signaling for Channels With 1-bit Quantization and Oversampling at the Receiver Rodrigo R. M. de Alencar, Student Member, IEEE, and Lukas T. N. Landau, Member, IEEE, Abstract—Continuous phase modulation (CPM) with 1-bit construction of zero-crossings. The proposed CPM waveform quantization at the receiver is promising in terms of energy conveys the same information per time interval as the common and spectral efficiency. In this study, CPM waveforms with CPFSK while its bandwidth can be the same and even lower. symbol durations significantly shorter than the inverse of the signal bandwidth are proposed, termed faster-than-Nyquist CPM. Referring to the high signaling rate, like it is typical for faster- This configuration provides a better steering of zero-crossings than-Nyquist signaling [9], the novel waveform is termed as compared to conventional CPM. Numerical results confirm a faster-than-Nyquist continuous phase modulation (FTN-CPM). superior performance in terms of BER in comparison with state- Numerical results confirm that the proposed waveform yields of-the-art methods, while having the same spectral efficiency and a significantly reduced bit error rate (BER) as compared to a lower oversampling factor. Moreover, the new waveform can be detected with low-complexity, which yields almost the same the existing methods [7], [6] with at least the same spectral performance as using the BCJR algorithm. efficiency. In addition, FTN-CPM can be detected with low- complexity and with a lower effective oversampling factor in Index Terms—1-bit quantization, oversampling, continuous phase modulation, faster-than-Nyquist signaling.
    [Show full text]
  • Digital Phase Modulation: a Review of Basic Concepts
    Digital Phase Modulation: A Review of Basic Concepts James E. Gilley Chief Scientist Transcrypt International, Inc. [email protected] August , Introduction The fundamental concept of digital communication is to move digital information from one point to another over an analog channel. More specifically, passband dig- ital communication involves modulating the amplitude, phase or frequency of an analog carrier signal with a baseband information-bearing signal. By definition, fre- quency is the time derivative of phase; therefore, we may generalize phase modula- tion to include frequency modulation. Ordinarily, the carrier frequency is much greater than the symbol rate of the modulation, though this is not always so. In many digital communications systems, the analog carrier is at a radio frequency (RF), hundreds or thousands of MHz, with information symbol rates of many megabaud. In other systems, the carrier may be at an audio frequency, with symbol rates of a few hundred to a few thousand baud. Although this paper primarily relies on examples from the latter case, the concepts are applicable to the former case as well. Given a sinusoidal carrier with frequency: fc , we may express a digitally-modulated passband signal, S(t), as: S(t) A(t)cos(2πf t θ(t)), () = c + where A(t) is a time-varying amplitude modulation and θ(t) is a time-varying phase modulation. For digital phase modulation, we only modulate the phase of the car- rier, θ(t), leaving the amplitude, A(t), constant. BPSK We will begin our discussion of digital phase modulation with a review of the fun- damentals of binary phase shift keying (BPSK), the simplest form of digital phase modulation.
    [Show full text]
  • Bandwidth Scaling of a Phase-Modulated CW Comb Through Four-Wave Mixing in a Silicon Nano-Waveguide
    Chalmers Publication Library Bandwidth scaling of a phase-modulated CW comb through four-wave mixing in a silicon nano-waveguide This document has been downloaded from Chalmers Publication Library (CPL). It is the author´s version of a work that was accepted for publication in: Optics Letters (ISSN: 0146-9592) Citation for the published paper: Liu, Y. ; Metcalf, A. ; Torres Company, V. (2014) "Bandwidth scaling of a phase-modulated CW comb through four-wave mixing in a silicon nano-waveguide". Optics Letters, vol. 39(22), pp. 6478-6481. Downloaded from: http://publications.lib.chalmers.se/publication/208731 Notice: Changes introduced as a result of publishing processes such as copy-editing and formatting may not be reflected in this document. For a definitive version of this work, please refer to the published source. Please note that access to the published version might require a subscription. Chalmers Publication Library (CPL) offers the possibility of retrieving research publications produced at Chalmers University of Technology. It covers all types of publications: articles, dissertations, licentiate theses, masters theses, conference papers, reports etc. Since 2006 it is the official tool for Chalmers official publication statistics. To ensure that Chalmers research results are disseminated as widely as possible, an Open Access Policy has been adopted. The CPL service is administrated and maintained by Chalmers Library. (article starts on next page) Bandwidth scaling of a phase-modulated CW comb through four-wave mixing in a silicon nano-waveguide Yang Liu,1* Andrew J. Metcalf,1 Victor Torres Company,1,2 Rui Wu,1,3 Li Fan,1,4 Leo T.
    [Show full text]
  • Module 3: Physical Layer
    Module 3: Physical Layer Dr. Natarajan Meghanathan Associate Professor of Computer Science Jackson StateMeghanathan University Jackson, MS 39217 Copyrights Phone: 601-979-3661 E-mail: [email protected] Natarajan 1 Topics • 3.1 Signal Levels: Baud rate and Bit rate • 3.2 Channel Encoding Standards – RS-232 and Manchester Encoding – Delay during transmission • 3.3 Transmission Order of Bits and Bytes • 3.4 Modulation Techniques – Amplitude, Frequency and PhaseMeghanathan modulation • 3.5 Multiplexing Techniques – TDMA, FDMA, StatisticalCopyrights Multiplexing and CDMA All Natarajan 2 Meghanathan Copyrights All Natarajan 3.1 Signal Levels: Baud Rate and Bit Rate Analog and Digital Signals • Data communications deals with two types of information: – analog – digital • An analog signal is characterized by a continuous mathematical function – when the input changes from one value to the next, it does so by movingMeghanathan through all possible intermediate values Copyrights • A digital signal has a fixed set of All valid levels Natarajan – each change consists of an instantaneous move from one valid level to another 4 Digital Signals and Signal Levels • Some systems use voltage to represent digital values – by making a positive voltage correspond to a logical one – and zero voltage correspond to a logical zero • For example, +5 volts can be used for a logical one and 0 volts for a logical zero • If only two levels of voltage are used – each level corresponds to one data bit (0 or 1). • Some physical transmission mechanismsMeghanathan
    [Show full text]
  • Performance of Coherent Direct Sequence Spread Spectrum
    PERFORMANCE OF COHERENT DIRECT SEQUENCE SPREAD SPECTRUM FREQUENCY SHIFT KEYING A thesis presented to the faculty of the Russ College of Engineering and Technology of Ohio University In partial fulfillment of the requirements for the degree Master of Science Sudhir Kumar Sunkara November 2005 This thesis entitled PERFORMANCE OF COHERENT DIRECT SEQUENCE SPREAD SPECTRUM FREQUENCY SHIFT KEYING by SUDHIR KUMAR SUNKARA has been approved for the School of Electrical Engineering and Computer Science and the Russ College of Engineering and Technology by David W. Matolak Associate Professor of Electrical Engineering and Computer Science Dennis Irwin Dean, Russ College of Engineering and Technology SUNKARA, SUDHIR KUMAR. M.S. November 2005. Electrical Engineering and Computer Science Performance of Coherent Direct Sequence Spread Spectrum Frequency Shift Keying (83pp.) Director of Thesis: David W. Matolak We analyze the performance of a multi-user coherently-detected direct sequence spread spectrum frequency shift keying modulated system. Detection is done with respect to an arbitrary user. We derive bit error probability expressions for both synchronous and asynchronous systems. For the synchronous system, we analyze different variations of the system in order to ensure orthogonality. Orthogonality is achieved via both frequency separation and orthogonal codes. In the asynchronous system, orthogonality is achieved only through frequency separation. The channel impairments considered were additive white Gaussian noise and multi-user interference. We then extend this to a Rayleigh fading channel, and provide analytical and simulation results for single user and multi- user cases. We also analyzed the spectral characteristics of these systems. Approved: David W. Matolak Associate Professor of Electrical Engineering and Computer Science Acknowledgements I would like to thank my thesis advisor Dr.
    [Show full text]
  • Amplitude and Frequency/Phase Modulation
    Amplitude and Frequency/Phase Modulation I always had difficulties in understanding frequency modulation (FM) and its frequency spectrum. Even for the pure tone modulation, the FM spectrum consists of an infinite number of sidebands whose signs change from one sideband to the next one and whose amplitudes are given by the horrible Bessel functions. I work for Zurich Instruments, a Swiss maker of lock-in amplifiers and it has become a professional inclination to always think in terms of demodulation. The pictorial representation of AM/FM that I like comes with a (pictorial) digression on lock-in demodulation. Reader not interested in demodulation should read only Sect. 1.1.3 and Sect. 1.21 1.1 Lock-in Demodulation as a Change to a Rotating Frame of Reference A lock-in amplifier can find the amplitude AS and phase 'S of an input signal of the type VS(t) = AS cos(!St + 'S): (1.1) by a process called demodulation. The existing literature explains demodulation with the multiplication of the input signal by sine and cosine of the reference phase, also referred to as the in-phase and quadrature of the reference: this reflects the low level implementation of the scheme (it is a real multiplication) but I could never really understand it. I prefer more a different explanation using complex numbers: first I will present the math, then an equivalent pictorial representation. 1.1.1 Demodulation of the Signal: a Mathematical Approach The signal of eq. (1.1) can also be written in the complex plane as the sum of two vectors (phasors), AS each one of length 2
    [Show full text]
  • Constant Envelope Multiplexing of Multi-Carrier DSSS Signals Considering Sub-Carrier Frequency Constraint
    electronics Article Constant Envelope Multiplexing of Multi-Carrier DSSS Signals Considering Sub-Carrier Frequency Constraint Xiaofei Chen 1,2,3,*, Xiaochun Lu 1,2,3, Xue Wang 1,2,3,* , Jing Ke 1,2,3 and Xia Guo 1 1 National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, China; [email protected] (X.L.); [email protected] (J.K.); [email protected] (X.G.) 2 University of Chinese Academy of Sciences, Beijing 100049, China 3 Key Laboratory of Precision Navigation and Timing Technology, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, China * Correspondence: [email protected] (X.C.); [email protected] (X.W.) Abstract: With the development of global navigation satellite systems (GNSS), multiple signals mod- ulated on different sub-carriers are needed to provide various services and to ensure compatibility with previous signals. As an effective method to provide diversified signals without introducing the nonlinear distortion of High Power Amplifier (HPA), the multi-carrier constant envelope mul- tiplexing is widely used in satellite navigation systems. However, the previous method does not consider the influence of sub-carrier frequency constraint on the multiplexing signal, which may lead to signal power leakage. By determining the signal states probability according to the sub-carrier frequency constraint and solving the orthogonal bases according to the homogeneous equations, this article proposed multi-carrier constant envelope multiplexing methods based on probability and homogeneous equations. The analysis results show that the methods can multiplex multi-carrier signals without power leakage, thereby reducing the impact on signal ranging performance.
    [Show full text]
  • Direct Sequence Spread Spectrum (DSSS) Digital Communications
    079.pdf DSSS Digital Communications A SunCam online continuing education course Direct Sequence Spread Spectrum (DSSS) Digital Communications By Raymond L. Barrett, Jr., PhD, PE CEO, American Research and Development, LLC www.SunCam.com Copyright 2010 Raymond L. Barrett, Jr. Page 1 of 43 079.pdf DSSS Digital Communications A SunCam online continuing education course 1.0 DSSS Introduction This course develops the theory and practical issues and examples leading up to Direct Sequence Spread Spectrum (DSSS) Communication. The information theoretic foundation for trading bandwidth and improved Signal-to-Noise Ratio (SNR) is introduced mathematically, but other useful properties associated with particular spreading sequence properties are introduced by example. The gradual development based on the Weaver architecture for frequency translation of single-sideband, suppressed carrier signals through digital QPSK examples into pseudo-noise (PN) sequence spreading of QPSK of sub-carrier sidebands and finally to direct-sequence, spread-spectrum QPSK is employed to build awareness of the relationships between the spectral energy and the modulation processes. The PN sequence generation, its auto-correlation and cross-correlation attributes are introduced and employed in example with a justification for the development of the matched- filter/correlator approach to sequence de-spreading. Some issues of carrier synchronization and problems are introduced but not developed in detail. Finally, the statistical properties of the correlator approach are shown to be the basis for Code-Division, Multiple Access (CDMA) spectrum sharing to ameliorate the extra bandwidth occupied by the spreading. 2.0 Information Theory and Spread Spectrum In 1948, Claude E. Shannon published his paper “A Mathematical Theory of Communication” containing his famous theorem and tying together prior work by Nyquist and others and starting the study of Information Theory.
    [Show full text]
  • Single Sideband Transmission by Envelope Elimination and Restoration
    Calhoun: The NPS Institutional Archive Theses and Dissertations Thesis Collection 1953 Single sideband transmission by envelope elimination and restoration. Elliott, Michael Murray. Monterey, California. Naval Postgraduate School http://hdl.handle.net/10945/24839 Il Library y. S. Naval Postgraduate School Monterey, California /?;. ^^f SINGLE SIDEB-VND TRAN^iMISSION BY ENVELOPE ELIMINATION AND RESTORATION « * * « « Hichaei M, tliiott SINGLE SIDEBAND TRANSMISSION BY ENVELOPE ELIMINATION AND RESTORATION by Michael Murray Elliott Lieutenant, United States Navy Submitted in partial fulfilljwnt of the requirements " of > , \CE IN ENGINEERING ELECTRONICS United States Naval r u ite School Monterey, v ^ i 19 5 3 IXliesJs This work is accepted as fulfilling the thesis requirements for the degree of RASTER OF SCIENCE IN ENGINEERING ELECTRONICS from the United States Naral Postgraduate School PREFACE December 12, 1901 was an eventful day in the history of radio con^ munication. Early that afternoon in a bitter cold barracks on Signal Hill, St, Johns, Newfoundland, Guglielmo Marconi eagerly strained forward as he heard a faint sputtering in his headphones. The sputtering was caused by an interrupted spark gap electromagnetic radiator 1700 miles away in southwest England, and the intelligence conveyed by that sputter^ ing was the letter "S" in Tntemational Morse Code* Ever since that day, scientists and engineers have been spurred on to develop more efficient, faster, and more flexible Beans of impressing intelligence on radio emissions. Many ineenious systems, some simple and some complex, have been devised to accomplish this modulation of the radio frequency emission. It is the aim of this paper to show the evolution of one such system, single sideband transmission by envelope elimination and restoration.
    [Show full text]