A TECHNICAL BRIEFING FOR AMATEUR RADIO OPERATORS Classical

A TECHNICAL BRIEFING FOR AMATEUR RADIO OPERATORS “Classical Modulations: The New Zero Bandwidth Concept” PRESENTED TO: ARASWF NAPLES, FL 34119 MARCH 2017 PRESENTED BY: DR. AL TORRES KP 4 AQI EMAIL: atorres 4850@yahoo. com 1

For Year 2017 ü January 2017: “Vertical Collinear Antennas: Better than a Dipole? ” ü February 2017: “How to See Radio Frequency (RF) Waves: the Carbon Magic” ü March 2017: “ Classical Modulations: The New Zero Bandwidth Concept ” 2

PRESENTATION OUTLINE • Classical Modulations • Modulation Types • Common Digital Modulation Types • Typical Spectral Bandwidths for Modulation Types • Amplitude Modulation (AM) • Frequency Modulation (FM) • Orthogonal Frequency Division Multiplex Modulation (OFDM) • The Zero Bandwidth Concept • Summary 3

CLASSICAL MODULATIONS: THE NEW ZERO BANDWIDTH CONCEPT • • Modulations are extremely necessary to transmit intelligence There are many types of modulations. Each modulation will exhibit a bandwidth based on frequency and based on transmission speed. Typically, as the modulation frequency increases, or the speed increases, the bandwidth also increases Each modulation has advantages and disadvantages; sometimes selection for a particular modulation is based on their individual attributes (noise, spectrum, interference, bandwidth, speed, collisions, efficiency, and others) • This presentation provides a concept for reducing spectral bandwidth regardless of the modulation type (PFM) 4

MODULATION TYPES • • Continuous Wave (CW) Amplitude Modulation (AM) – Double-sideband modulation (DSB) • Double-sideband modulation with carrier (DSB-WC)[use on the AM radio broadcasting band] • Double-sideband suppressed carrier transmission (DSB-SC) • Double-sideband reduced carrier transmission (DSB-RC) Single Sideband Modulation (SSB or SSB-AM) – Single –sideband modulation with carrier (SSB-WC) – Single-sideband modulation suppressed carrier modulation (SSB-SC) Vestigial Sideband Modulation (VSB or VSB-AM) Quadrature Amplitude Modulation (QAM) Angle Modulation (constant envelope) Frequency Modulation (FM) Phase Modulation (PM) 5

MODULATION TYPES CONT. • Transpositional Modulation (TM): the waveform inflection is modified resulting in a signal where each quarter cycle is transposed in the modulation process. TM is a pseudo-analog modulation (AM) • Phase-Shift Keying (PSK): a finite number of phases are used • Frequency-Shift Keying (FSK): a finite number of frequencies are used • Amplitude-Shift Keying (ASK): a finite number of amplitudes are used • Quadrature-Shift Keying (QAM): a finite number of at least two phases and at least two amplitudes are used 6

COMMON DIGITAL MODULATION TYPES • • • Phase Shift Keying (PSK) – Binary PSK (BPSK), using M=2 symbols – Quadrature PSK (QPSK), using M=4 symbols – 8 PSK, using M=8 symbols – 16 PSK, using M=16 symbols – Differential PSK (DPSK) – Differential QPSK (DQPSK) – Offset QPSK (OQPSK) – π/4–QPSK Frequency-Shift Keying (FSK) – Audio Frequency Shift Keying (AFSK) – Multi-Frequency Shift Keying (M-ary FSK or MFSK) – Dual-Tone Multi-Frequency (DTMF) – Amplitude-Shift Keying (ASK) On-Off Keying (OOK), the most common ASK form – M-ary Vestigial sideband modulation, for example 8 VSB 7

COMMON DIGITAL MODULATION TYPES Cont. • Orthogonal Frequency-Division Multiplexing (OFDM) modulation • Discrete Multi-tone (DMT), including adaptive modulation and bit-loading • Wavelet Modulation • Quadrature Amplitude Modulation (QAM), a combination of PSK and ASK – Polar Modulation (Po. M) like QAM a combination of PSK and ASK – Continuous Phase Modulation (CPM) methods – Minimum-Shift Keying (MSK) – Gaussian Minimum-Shift Keying (GMSK) – Continuous-Phase Frequency-Shift Keying (CPFSK) 8

COMMON DIGITAL MODULATION TYPES Cont. • Spread-Spectrum techniques – Direct-Sequence Spread Spectrum (DSSS) – Chirp Spread Spectrum (CSS) according to IEEE 802. 15. 4 a CSS uses pseudo-stochastic coding – Frequency-Hopping Spread Spectrum (FHSS) applies a special scheme for channel release • Trellis Coded Modulation (TCM), also known as Trellis Modulation 9

TYPICAL SPECTRAL BANDWIDTHS FOR MODULATION TYPES • • CW SSB AM FM FM Broad TV WIFI (802. 11) 50 -200 Hz 2. 4 -4. 0 KHz 6. 0 KHz 5 KHz 200 KHz 6 -10 MHz 40 MHz 10

AMPLITUDE MODULATION • • • Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave In amplitude modulation, the amplitude (signal strength) of the carrier wave is varied in proportion to the waveform being transmitted AM was the earliest modulation method used to transmit voice by radio. It was developed during the first two decades of the 20 th century beginning with Roberto Landell De Moura and Reginald Fessenden’s radiotelephone experiments in 1900 It remains in use today in many forms of communication; for example it is used in portable two way radios, VHF aircraft radios, Citizen’s Band Radio, and in computer modems (in the form of QAM) "AM" is often used to refer to mediumwave AM radio broadcasting 11

BASIC CONCEPT FOR AM 12

AMPLITUDE MODULATION (AM) WITH DIFFERENT MODULATION LEVELS 13

FREQUENCY MODULATION (FM) • • In telecommunications and signal processing, frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. This contrasts with amplitude modulation, in which the amplitude of the carrier wave varies, while the frequency remains constant Advantages of frequency modulation – Resilient to noise: One of the main advantages of frequency modulation that has been used by the broadcasting industry is the reduction in noise. As most noise is amplitude based, this can be removed by running the signal through a limiter so that only frequency variations appear. – Resilient to signal strength variations: In the same way that amplitude noise can be removed, so too can any signal variations. This means that one of the advantages of frequency modulation is that it does not suffer audio amplitude variations as the signal level varies, and it makes FM ideal for use in mobile applications where signal levels constantly vary. This is provided that the signal level is sufficiently high to allow the signal to be limited. 14

ADVANTAGES OF FM • Does not require linear amplifiers in the transmitter: As only frequency changes are required to be carried, any amplifiers in the transmitter do not need to be linear • Enables greater efficiency than many other modes: The use of non-linear amplifiers, e. g. class C, etc. means that transmitter efficiency levels will be higher - linear amplifiers are inherently inefficient (25% vs. 70%) 15

FM (MODULATING SIGNAL AND RF SIGNAL) 16

WHAT IS OFDM MODULATION? • • • A relatively new method for providing multiple access (users) with minimum interference Takes a normal voice or data carrier and splits it into many mini and sometimes micro carriers. Each mini or micro can be as small as 50 Hz. Each mini/micro carrier is then rotated 90 degrees from the previous carrier, example: – CARRIER 1: 0 DEGREES – CARRIER 2: 90 DEGREES – CARRIER 3: 180 DEGREES – CARRIER 4: 270 DEGREES If a carrier “collides” with another carrier either in time or in frequency, the carrier is nullified. But since the carriers only carry a fraction of the “information”, the impact to the total message is minimal New Bluetooth devices are starting to use OFDM modulation 17

OFDM CARRIER MINI/ MICRO CARRIERS 18

THE ZERO BANDWIDTH CONCEPT • In an angle modulated radio transmitter (or FM), the total power is the same when modulated or unmodulated • The power in the sidebands is derived from the carrier • When a complex modulating waveform is applied, the power and the amplitude of the carrier is varying • If the sidebands are phased out, what is left is a single spectrum component varying in amplitude • These amplitude variations can be used to transmit digital information on nearly-zero bandwidth without sacrificing data speed 19

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THE ZERO BANDWIDTH CONCEPT • Work is still in progress regarding testing of different modulations • If the concept works as theory predicts, then we can provide “communications” with the use of much lower spectral bandwidth • Impact of spectral bandwidth reduction: – Less interference in the HF Bands – Lower cost to produce hardware (transmitters/receivers) – Better matching antennas and RF circuits – Faster digital communications – Data pulse rates exceeding the Shannon-Hartley communications theorem • Testing to be completed by the middle of this year! 23

SUMMARY • We have reviewed the “Classical” modulation types • Modulations types are multiple and each modulation attributes provide advantages and disadvantages • Each modulation type will provide a spectral bandwidth requirement • Spectral Bandwidth is proportional to frequency, modulation type, and transmission speed • Orthogonal Frequency Division Multiplex (OFDM) promises to be the “next” breakthrough in modulation schemes • Zero Bandwidth concept is presently being researched; if successful, it will provide a significant breakthrough in amateur communications in the near future 24

MORE INFORMATION or COPY OF PRESENTATION • SEND AN EMAIL TO THE FOLLOWING URL: atorres 4850@yahoo. com CONTACT ME AT: AL TORRES KP 4 AQI P. O. BOX 24283 DAYTON, OH 45424 -0283 25