Link Budget Analysis: Digital Modulation, Part 1 Atlanta RF Services, Software & Designs

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1 Link Budget Analysis: Digital Modulation, art 1

2 resentation Content Link Budget Analysis: Digital Modulation, art 1 1. Sources of Communication Data.. Metrics for Choice of Modulation. A. ower Efficiency. B. Bandwidth Efficiency. 3. Digital Modulation Trade-offs. 4. Modulation: Types & Techniques. 5. ower Transfer into Free Space. 6. Digital Bandpass Modulations. 7. Modulation in Wireless App. 8. erformance Advantages. 9. Digital Modulation rocess. 10. Digital Communication System. 11. BER: An Introduction. 1. Bit Rates & Transmission Channels 13. ASK: Amplitude Shift Keying. 14. ASK: Basis of operation. 15. ASK: Implementation. 16. SD of Bandpass Binary ASK. 17. Error roaility of M-ary ASK. 18. Executive Summary. May-013 Refer to s presentation titled: Link Budget Getting Started, which can e downloaded from our wesite:

3 Typical Sources of Communication Data Link Budget Analysis: Digital Modulation, art 1 1. Analog Data Sources: roduces continuous-time output using a device that converts the real analog signal to electrical voltage. A. Speech/Voice/Telephone. B. Music/Sound. C. Moving and static images. D. And also: temperature, speed, time.... Digital Data Sources: roduces discrete-time output using a device that processes logical digital signals (inary, ASCII). A. Computer files/keyoards/monitors/rinters. B. sent over the internet. C. Digital storage devices (Compact Discs, DVDs, etc ) D. JEG/MEG files. May

4 May Metrics for Choice of Modulation Scheme Link Budget Analysis: Digital Modulation, art 1 1. High spectral efficiency: η.... Signal uses a small andwidth. A. Transmitted signal occupies the minimum RF channel andwidth.. High power efficiency: η p Detect a small signal power. A. rovides low it-error rates (BER) at low Signal-to-Noise (S/N) ratios. 3. High data rates: Bits per second. 4. Roust to multipath effects & fading conditions. 5. Easy to implement and cost-effective to operate. 6. Low carrier-to-cochannel signal interference ratio. 7. Low out-of-and radiation. 8. Constant or near constant envelope: A. Constant envelope: Only phase is modulated; can use power-efficient non-linear amplifiers. B. Non-constant envelope: hase and amplitude modulated; may need power-inefficient linear amplifiers.

5 ower Efficiency of Digital Modulation A performance metric for digital communication systems 1. ower efficiency is the aility of a modulation technique to preserve the fidelity/quality of digital messages at low power levels, and is expressed as the ratio of the signal energy per it (E, watt-sec) to the noise power spectral density per it (N 0, watts/hertz) required to achieve a given proaility of it error rate, say BER ~ 10 5 : E ower Efficiency : p N0. To otain good fidelity/quality, the signal power usually needs to e increased for etter noise immunity. A. Tradeoff etween signal fidelity (BER) and signal power (E /N o ). B. ower efficiency descries how efficient this tradeoff is made. 3. There are cases when andwidth is availale ut transmit power is limited. A. In these cases as M goes up, the andwidth increases ut the required power levels to meet a specified BER remains stale. 4. Modulations that are power-limited achieve their goals with minimum expenditure of power at the expense of andwidth. Examples are MFSK and other orthogonal signaling. May required at the receiver input for certain BER

6 Bandwidth Efficiency of Digital Modulation A performance metric for digital communication systems 1. Bandwidth (Spectral) efficiency descries the aility of a modulation scheme to accommodate data within a limited frequency andwidth. In general, it is defined as the ratio of the throughput data it rate: R, in its per second, to the required frequency andwidth occupied y the modulated RF signal: B T, in hertz: Bandwidth Efficiency : B R B T, its/second/hz. Bandwidth efficiency reflects how efficiently the allocated frequency andwidth is utilized. Tradeoff etween data rate: R and pulse width: T s (B T ~ 1/T s ). 3. Channel capacity gives an upper ound of achievale andwidth efficiency. 4. There are situations where andwidth is at a premium, so modulations with large throughput data rate per hertz are needed (large η B = R /B T ). 5. Hence we need standards with large time-andwidth product: B T T. 6. The GSM standard uses Gaussian minimum shift keying (GMSK) with B T T = Modulations that achieve it error rates at a minimum expenditure of andwidth, ut possily at the expense of too high a signal power, are andwidth-limited. A. Examples are variations of MSK and many QAM. May

7 May Tradeoff: BW Efficiency and ower Efficiency Link Budget Analysis: Digital Modulation, art 1 1. Fundamental tradeoff etween Bandwidth Efficiency: η B and ower Efficiency: η p.... in general: A. If η B improves, then η p deteriorates (or vice versa). 1) May need to waste more signal power: E /N o to get a etter data rate: R. ) May need to use less signal power (to save on attery life) at the expense of a lower data rate. B. η B versus η p is not the only consideration. 1) Use other factors to evaluate system complexity, resistance to MRC impairments, etc.. Adding error control coding improves the power efficiency (there are fewer errors), ut reduces the andwidth efficiency (redundant data its are also transmitted, which requires more andwidth). 3. M-ary modulation schemes increase the andwidth efficiency ut requires higher transmission power to keep the same it error rate: BER.

8 Digital Modulation Tradeoffs Link Budget Analysis: Digital Modulation, art 1 1. Linear Modulation: A. The amplitude of the modulated transmitted signal: s(t), varies linearly with the modulating digital signal: m(t). Bandwidth efficient ut power inefficient. Examples: M-ASK, M-AM, BSK, DSK, QSK, π/4 SK, M-QAM. B. Information encoded in carrier signal s amplitude and/or in carrier s phase. C. Easier to adapt. More spectrally-efficient then nonlinear modulation. D. Issues: differential encoding, pulse shaping, it mapping. A. Often requires linear power amplifiers to minimize signal distortions.. Nonlinear Modulation: A. The amplitude of the modulated transmitted signal: s(t), does not vary linearly with the modulating digital signal: m(t). ower efficient ut andwidth inefficient. Examples: FSK, MSK, GMSK, constant envelope modulation. B. Information encoded in carrier signal s frequency. C. Continuous phase (CFSK) modulation is a special case of FM. D. Bandwidth determined y Carson s rule (1) (pulse shaping). E. More roust to channel and power amplifier s nonlinearities. 1: J.R. Carson, "Notes on the theory of modulation, roceedings of IRE, vol. 10, no. 1 (Fe. 19), pp May

9 Modulation: Types and Techniques Link Budget Analysis: Digital Modulation, art 1 1. Analog Modulation: When the information-earing message signal is continuous-time analog, then the modulation is called analog modulation. Common analog modulation techniques: A. AM: Amplitude modulation : Message is carried in A(t). S(t) = A(t) cos(ω c t + φ 0 ). B. FM: Frequency modulation: Message is carried in ω(t). S(t) = A 0 cos(ω(t) + φ 0 ). C. M: hase modulation : Message is carried in φ(t). S(t) = A 0 cos(ω c t + φ(t)).. Digital Modulation: When the information-earing message signal is discrete-time digital, then the modulation is called digital modulation. Common digital modulation techniques: A. ASK: Amplitude Shift Keying : Message signal changes the carrier s amplitude. B. FSK: Frequency Shift Keying: Message signal changes the carrier s frequency. C. SK: hase Shift Keying : Message signal changes the carrier s phase. D. QAM: Quadrature Amplitude Modulation. A comination of ASK and SK. 3. For Binary (-level) Digital Modulation (M = ): A. BASK: Binary Amplitude Shift Keying. B. BFSK: Binary Frequency Shift Keying. C. BSK: Binary hase Shift Keying. May

10 Types of Digital-to-Analog Modulations si ( t) Ai ( t)cos(f it i( t)) n Time-varying Amplitude Time-varying Frequency Time-varying hase Digital-to-Analog Modulation Techniques Bit rate is the numer of its transmitted per second: R = kr s. Baud rate is the numer of signal elements transmitted per second: R s = R /k. In the analog transmission of digital data, if a signal unit is composed of k its, then the it rate is k times higher than aud rate. Baud rate determines the channel andwidth required to transmit the modulated signal. May

11 Digital Bandpass Modulation Techniques Link Budget Analysis: Digital Modulation, art 1 In digital communications, the modulating aseand message signal: m(t) is a inary or M-ary digital data stream. The carrier is usually a sinusoidal signal. Voltage T 1. Baseand digital message signal: m(t). Analog sinusoidal carrier signal: A. Carrier signal: A c cos( πf c t + c ) 3. ASK: Amplitude Shift Keying. A. Message signal changes the carrier s amplitude : A i (t). 4. FSK: Frequency Shift Keying. A. Message signal changes the carrier s frequency : f i (t). Digital Signal Carrier Signal ASK Signal FSK Signal Time Time Time Time 5. SK: hase Shift Keying. A. Message signal changes the carrier s phase : i (t). SK Signal May Time

12 Types of Digital Modulation Techniques Link Budget Analysis: Digital Modulation, art 1 1. Amplitude Shift Keying: ASK A. On-Off Keying: OOK. B. Binary Amplitude Shift Keying: BASK.. Frequency Shift Keying: FSK A. Binary Frequency Shift Keying: BFSK. B. 4-level Frequency Shift Keying: 4-FSK. 3. hase Shift Keying: SK A. Binary hase Shift Keying: BSK. B. Quadrature hase Shift Keying: QSK, DQSK, OQSK, π/4-qsk. C. 8-Level hase Shift Keying: 8-SK. D. 16-Level hase Shift Keying: 16-SK. 4. Quadrature Amplitude Modulation: QAM A. 16-QAM C. 18-QAM E. etc.... B. 64-QAM D. 65-QAM 5. Continuous hase Modulation: CFSK A. Minimum Shift Keying: MSK B. Gaussian MSK: GMSK May Digital signal with two signal levels Digital signal with four signal levels

13 Multi-level Signaling: Digital M ary Modulation Link Budget Analysis: Digital Modulation, art 1 1. In general, multi-level (M-ary) digital communication is used to design a communication system that is more andwidth efficient. With M-ary signaling, digital inputs with more than two modulation levels are allowed on the transmitter s input.. The data is transmitted in the form of symols, each symol is represented y k its, so there are M = k different signal levels in M-ary modulation. 3. In M-ary data transmission, one of M possile signals is transmitted during each signaling interval: T s, where: T s = kt and T = it time interval. 4. There are many different M ary modulation techniques, some of these techniques modulate one carrier parameter, like: Amplitude, or hase, or Frequency: A. M ary ASK: M ary Amplitude Shift Keying: M-ASK or M-AM. 1) The carrier signal s amplitude takes on M different levels. ) Used in aseand transmission: ulse Amplitude Modulation (AM) and in andpass transmission: ASK. B. M ary SK: M ary hase Shift Keying: M-SK. 1) The carrier signal s phase takes on M different levels. C. M ary FSK: M ary Frequency Shift Keying: M-FSK. 1) The carrier signal s frequency takes on M different levels. May

14 Modulation in Wireless Applications Link Budget Analysis: Digital Modulation, art 1 1. Analog FM: AMS Advanced Moile hone System at 850 MHz.. GMSK: Gaussian Minimum Shift Keying: A. GSM Gloal System for Moile Communications at 900 MHz. B. DCS Digital Cellular System at 1800 MHz (USA) C. CS1900 ersonal Communication System at 1900 MHz (USA) D. DECT Digital European Cordless Telephone at MHz (Europe) E. CT Cordless Telephone (Canada) 3. π/4-dqsk: π/4 Differential Quadrature hase Shift Keying A. IS-54 at 900 MHz/IS-136 at GHz (North America) B. DC ersonal Digital Cellular at 800 & 1500 MHz/HS (Japan) 4. QSK(FL)/DQSK(RL): IS-95 (North America Digital Cellular): A. Data Rate = 48k/s; Bandwidth = 30kHz B. Bandwidth efficiency = 48/30 = 1.6its/sec/Hz 5. BSK, QSK, OFDM: IEEE80.11 at.4 GHz & 5 GHz (ISM and). 6. GFSK: Bluetooth at.4 GHz (Industrial-Scientific-Medical and). May

15 May Modulation Formats in Cale Link Budget Analysis: Digital Modulation, art 1 Modulation Description Use Comments AM, FM, M Amplitude Modulation Frequency Modulation and hase Modulation Radio, Citizens Band, Cale Low Spectral Efficiency. AL, NTSC hase Alternate Line, National Television System Committee Commercial Television and Cale Low Spectral Efficiency. Noise viewale y users. QSK, BSK, FSK Quadrature hase Shift Keying, Binary hase Shift Keying, Frequency Shift Keying Cale modem return path, DVB-S, Telemetry channels Roust in poor signalto-noise. VSB artially-suppressed - carrier Vestigial Sideand North American roadcast digital television Good performance in multi-path conditions. QAM Quadrature Amplitude Modulation Digital cale roadcast, DVB-C, Cale modems Requires good signalto-noise. S-CDMA Synchronous Code Division Multiple Access DOCSIS.0 return path Good performance in poor signal-to-noise.

16 erformance Advantages of Digital Transmission When compared to Analog Modulation 1. Digital transmission produces fewer data errors than analog transmission: A. Data integrity & noise immunity: Easier to detect and correct information-earing data errors, since transmitted data is inary (1 s & 0 s : only two distinct values). B. Error coding is used to detect and correct digital transmission errors. C. Regenerative capaility: Regenerative digital repeaters placed along the transmission channel can detect a distorted digital signal and retransmit a new, clean digital data signal. These repeaters minimize the accumulation of noise and signal distortion along the transmission channel.. ermits higher transmission data rates: Economical to uild transmission links of very high andwidth. Optical fier designed for digital transmission. 3. Better spectral efficiency: Effective use of limited frequency resources (narrow andwidth) to send a large amount of data. 4. Security & privacy: Enales encryption algorithms in information-earing digital it stream signals. Deters phone cloning and eavesdropping. 5. Easy to multiplex multiple sources of information: Voice, video and data in a single transmission channel, since all signals are made up of 1 s and 0 s. 6. Easy to integrate computer/communication systems. 7. Digital equipment consumes less DC power in a smaller physical size. May

17 May Disadvantages of Digital Transmission When compared to Analog Modulation Disadvantages: 1. More Bandwidth Needed: A. Transmission of digitally encoded analog signals requires significantly more andwidth than simply transmitting the original analog signal.. Circuit complexity: A. Analog signals must e converted to digital pulses prior to transmission and converted ack to their original analog form at the receiver: Additional encoding/decoding circuitry needed. 3. Synchronization: A. Requires precise time synchronization etween the clocks in the transmitter and in the receiver.

18 Digital Bandpass Modulation rocess Overview 1. Digital Modulation involves translating the aseand digital message signal: m(t), to a andpass analog signal: s(t), at a carrier frequency: f c, that is very high compared to the digital aseand frequency: f. The choice of carrier frequency allows placement of the composite modulated signal in a desired frequency and for signal processing. Modulation allows many signals with different carrier frequencies to share the frequency spectrum.. Digital Modulation is achieved y switching or keying (i.e.: varying) the amplitude, phase and/or frequency of a high-frequency sinusoidal analog carrier signal: s(t) in accordance with the incoming information-earing digital aseand message signal: m(t), a time sequence of symols or pulses, therey resulting in a andpass modulated signal that is transmitted y the sender over a channel. Modulated signals propagate well through the atmosphere. 3. Changes in the amplitude, phase and/or frequency of the carrier signal are used to represent a digital state of the modulating digital aseand signal. 4. Using this technique, digital or analog data is encoded into a digital signal. 5. A andpass carrier signal modulated y aseand digital data has the form: si ( t) Ai ( t)cos(f it i( t)) n where digital data its are encoded in discrete time-varying amplitude A i (t) (= ASK), discrete time-varying phase: i (t) (= SK), or discrete time-varying frequency: i = π(f c - f i )t (= FSK), which remain constant over a data it time interval: T. May

19 May Basic Digital Communications System Link Budget Analysis: Digital Modulation, art 1 Analog In: Audio Video Data Source Digital input Digital output User Analog Out: Audio Video Anti-alias lowpass filter Source Encoder Transmit Receive Low pass filter A/D Nyquist sampling Source Decoder D/A Quantization noise Source its Source its Channel Encoder FEC ARQ Block Convolution ulse shaping filter ISI Baseand Channel Decoder Channel its Baseand Channel its Regenerate FEC Matched filter ARQ Decision threshold Block Timing recovery Convolution Bandpass Modulator ASK FSK SK Binary M ary Demodulator & Detect assand Envelope Coherent Carrier recovery Multiple Access FDMA TDMA CDMA Analog Waveforms Multiple Access Transmit Channel Bandpass Filter Communications Channel: ath Loss Noise Distortion Interference Receive Channel Bandpass Filter Tx Rx

20 Building a Digital Communications System Link Budget Analysis: Digital Modulation, art 1 1. Source Encoder: Samples and quantizes a time- & amplitude-varying analog signal, and converts the samples into a digital inary it stream of 1 s and 0 s, then encodes it into a shorter digital signal (reduces the redundancy or reduces the andwidth requirement: data compression). Goal: Minimize signal distortion.. Channel Encoder: Accepts the digital signal and encodes it into a longer digital signal y introducing redundant data its in the information sequence for the purpose of comating the effects of noise and interference in the transmission channel, therey minimizing transmission errors. 3. Modulator: Converts the digital information data sequences into high frequency carrier waveforms that are compatile with the characteristics of the transmission channel. Varies the amplitude, phase and/or frequency of the carrier waveform. 4. Transmission: Carrier modulated digital symols are transmitted towards the desired destination, using a certain physical medium (Guided: cale, optical fier and Unguided: wireless). 5. Channel estimation: Generally, transmission channels may introduce distortion to the source signal, and the characteristics of the channel distortion need to e estimated or identified at the receiver end, in order to reduce or eliminate the distortion and recover the original signal. This is called channel estimation or identification. May

21 May Bit Error Rate (BER): An Introduction Link Budget Analysis: Digital Modulation, art 1 1. Bit Error Rate is a major indicator of the health of the communication system.. As data is transmitted some of the its may not e received correctly. 3. The more its that are incorrect, the more the signal will e affected. 4. It s important to know what portion of the its are in error. 5. Need to know how much margin the system has efore failure. 6. Good signal: BER < Threshold for visile degradation: BER ~ Example: A. A 56QAM channel transmits at a symol rate of 5M symols per second. B. Bit rate = 8 its per symol X 5M symol per second = 40M its per second. C. Error Incident = Bit rate X BER = Errors er Second.

22 Bit Rates of Digital Transmission Systems Link Budget Analysis: Digital Modulation, art 1 System Bit Rate Oservations Telephone twisted pair Ethernet twisted pair kps 4 khz telephone channel 10 Mps, 100 Mps 100 meters of unshielded twisted copper wire pair Cale modem 500 kps-4 Mps Shared CATV return channel ADSL twisted pair kps in, Mps out Coexists with analog telephone signal.4 GHz radio -11 Mps IEEE wireless LAN 8 GHz radio Mps 5 km multi-point radio Optical fier.5-10 Gps 1 wavelength Optical fier >1600 Gps Many wavelengths May-013

23 Examples of Transmission Channels Link Budget Analysis: Digital Modulation, art 1 Channel Bandwidth Bit Rates Telephone voice channel 3 khz 33 kps Copper pair 1 MHz 1-6 Mps Coaxial cale 500 MHz (6 MHz channels) 30 Mps/ channel 5 GHz radio (IEEE 80.11) 300 MHz (11 channels) 54 Mps / channel Optical fier Many TeraHertz 40 Gps / wavelength May

24 May ASK: Amplitude Shift Keying One dimensional linear modulation 1. Binary (-level) ASK: BASK (1-it: signal levels) Binary Data BASK signal. 4-level ASK: 4-ASK (-its: 4 signal levels) Binary Data 4-ASK signal

25 ASK: Amplitude-Shift Keying Basis of operation 1. When the aseand signal modulates the amplitude of the carrier signal, the process is called amplitude modulation. For digital aseand signals, it is called Amplitude Shift Keying : ASK. Also referred to as AM: ulse Amplitude Modulation.. Amplitude-Shift Keying (ASK) is a form of digital modulation that represents digital data solely as variations in the amplitude of a carrier signal. 3. In ASK, the amplitude of the carrier signal is changed etween two (or more) levels y the digital information message signal: m(t) to represent a inary it 0 or a inary 1. The carrier signal s center frequency: f c and phase: c remain constant. 4. For inary ASK (BASK), inary digit 1 is represented y the presence of the carrier signal, at constant amplitude, during a it period: T, while inary it 0 is the asence of the carrier during a it period. If T indicates the time duration of one information it, the two time-limited modulated signals can e expressed as: E i(t) cos( πfct φ c) for a inary 1 ; m(t) 1 s( t ) ASK Ac m( t )cos fc t c T 0 for a inary 0 ; m(t) 0 5. Carrier frequency: f c = n c /T, Hertz, for some fixed integer: n c. 6. On-Off Keying (OOK) is also called Amplitude Shift Keying (ASK), which consists of keying (i.e.: switching) a carrier sinusoid on and off with a uni-polar inary signal. 7. Since noise affects the amplitude of a signal, ASK is highly susceptile to noise interference, fading, and electromagnetic induction. ASK is also most susceptile to the effects of nonlinear devices, which compress and distort the signal s amplitude. It is rarely used on its own. May

26 BASK: Binary Amplitude Shift Keying T T 3T 4T 5T Implementation of Binary ASK: Amplitude Message m(t) Digital signal Time C(t) ASK signal S ASK (t) T Time Time May

27 ower Spectral Density of Bandpass Binary ASK Assumes aseand rectangular pulses: ( v f ) 1 4 g f f f f o g o E sin( ( f fo) / R ) 8 ( ) / R f fo R f = R Energy per it: E = T, watts-second. Null-to-Null RF transmission andwidth: B null = (f o + f ) (f o f ) = f = R = /T. Bandwidth with 95% of the total transmitted power: B 95% = 3f (Hz), centered at f o. May

28 Error roaility for M- ary Amplitude Shift Keying In an Additive White Gaussian Noise (AWGN) channel A. s ( t ) ASK B. Modulated signal for Multi -Level ASK modulation : roaility of symol error for coherently detected se, MASK E i( t ) cos( πfct) T (M 1) Q M E N o g 6 (M 1) Q M i 1 M ( M 1)T erfc E s cos( πf (6 log M)E (M 1)N (M 1) where: Es ( log M)E Eg Average en ergy/symol. 3 C. roaility of it error (BER) for M- ary ASK : D. Binary ASK (M ) it e, MASK e,bask Q se,mask log M E N s o Q se,mask k E N o, where: 1 k log error proailit y : E N May o M 3 o Multi -Level ASK modulation c t), where E (M 1) erfc M i E g i 1 M ( 3log M)E (M 1)N 4-ASK Signal Constellation Diagram: s 1 s E g E g 0 : o s 3 s 4 Eg 3 Eg ( t 1 )

29 Error roaility for M- ary Amplitude Shift Keying In an Additive White Gaussian Noise (AWGN) channel 1. The average proaility of it error (BER) for Multi-Level Amplitude Shift Keying (M-ASK) modulation using coherent detection is: e, MASK where: E (M 1) Q M log M s ( log M)E E N o g (M 1) Q M log M (M 1) E 3 g (6 log M)E (M 1)N Average energy/symol and k log o (M 1) erfc M log M ( 3log M)E (M 1)N M,its / symol. o M k roaility of Bit Error (BER): e M k roaility of Bit Error (BER): e 3 erfc 8 15 erfc erfc erfc 048 6E 15N o 1E 55N o 18E 4,095N o 4E 65,535N o 4 e,4 ASK e,16 ASK e,64 ASK e,56 ASK 51 9 May e,8 ASK e,3 ASK e,18 ASK e,51 ASK erfc erfc erfc erfc 9E 63N o 15E 1,03N o 1E 16,383N o 7E 6,143N o

30 roaility of Bit Error (BER): M ary ASK In an Additive White Gaussian Noise (AWGN) channel roaility of symol error for coherently detected se, MASK where: E (M 1) Q M s ( log M)E E N o g (M (M 1) Q M 1) E 3 (6 log M)E (M 1)N Average energy/symol and k May k,its/ symol = M signal levels = E /N o, db E /N o roaility of Bit Error: e,mask E E E E E-13.76E E E-09.17E E E E E E+00.63E E E E E-1.63E E E E+00.7E g Multi -Level ASK modulation o (M 1) erfc M log ( 3log M)E (M 1)N for Multi -Level ASK : M, its/symol. roaility of it error (BER) e, MASK where: k se,mask log M log The complementary error function: erfc is uilt into most spreadsheet software programs, like: Excel. : k o se,mask M, its/symo l

31 roaility of Bit Error: e,mask 1.E+00 1.E-01 roaility of Bit Error (BER): M-ASK roaility of Symol Error for M- ASK : se, MASK (M 1) erfc M ( 3log M)E (M 1)N o 1.E-0 1.E-03 k = its/symol k = 3 its/symol k = 4 its/symol k = 5 its/symol M = 3 k = 5 1.E-04 M = 16 k = 4 1.E-05 1.E-06 roaility of Bit Error (BER) for M- ASK : e, MASK se,mask log M where: k log se,mask k M, its/symo l. M = 4 k = M = 8 k = 3 1.E E /N o, db E /N o = Signal energy per it over Noise density per it May

32 Summary: Digital Modulation, art 1 1. Digital Modulation continues to dominate the world of data & voice communication with high throughput within a congested frequency spectrum at affordale cost.. Design trade-offs for power-limited systems and andwidth-limited systems often narrows the choice of digital modulation techniques. 3. Amplitude Shift Keying provides a simple & cost-effective method for communication, ut is rarely used on its own, due to poor susceptiility to noise and distortion. 4. Look for additional presentations from on Digital Modulation techniques, and visit our wesite: to download these and other topics on Link Budget Analysis. Refer to ackground material in s presentation titled: Link Budget Getting Started, which can e downloaded from our wesite: May

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34 resentations y, LLC Download various presentations at our wesite: : 1. Satellite: LEO, MEO & GEO.. Antennas: An Overview. 3. Link Budget: Getting Started. 4. Link Budget: Digital Modulation art 1 (Overview & M-ASK). 5. Link Budget: Digital Modulation art (M-FSK). 6. Link Budget: Digital Modulation art 3 (M-SK & QAM). 7. Link Budget: Error Control & Detection. 8. Multiple Access Techniques: FDMA, TDMA and CDMA. 9. Insertion Loss: Doule Ridge Waveguide. 10.RF Filters: An Overview. 11.Multi-Section Symmetrical Directional Couplers. 1.arallel Coupled Bandpass Filters. Visit our wesite often as presentations are added for your viewing pleasure. May