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Review of Digital Modulation
Dr. A.K.MukhopadhyayDepartment of ECE, Dr. B.C.Roy Engg
College, Durgapur
AKM/DigCom/Mod/1
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Types of Signal Transmission
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fCfC
Modulation Basic Principles
Modulating
Signal m(t), at
baseband(fB)
Carrier (fC)
Modulation on carriers
amplitude, frequencyor phase
Modulated Signal
carrying theinformation of
m(t), bandpass (fC)
AKM/DigCom/Mod AKM lecture notes on
The modulating signal is represented as a time-sequence of symbolsor pulses. Each symbol has mfinite states and carries nbits of informationwhere n= log2m bits/symbol.
One symbol (has mstates voltage levels)
(represents n= log2mbits of information)
...
0 1 2 3 TModulator
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Digital Modulation Features
The input is discrete signal (pulses or symbols in time sequence)
Robust against channel impairmentsEasier multiplexing of voice, data, video informations
Digital error-control codes
Encryption of the transferred signals
More secure link
Modulating signal is a binary or M-ary data
The carrier is usually a sinusoidal wave.
Change in Amplitude (ASK), Frequency (FSK), Phase(PSK)and combination of more than one parameters
(Hybrid/Multilevel ). Ex. : QAM (Phase and Amplitude
change), M-ary
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Digital Modulation Benefits
Provides low bit-error rates at low SNRsPower efficiency
Performance in multipath and fading conditionsNoise immunity efficiency
Minimum RF channel bandwidthBandwidth efficiency
Easy and cost-effective implementationTradeoffs for selecting a digital modulation scheme depending
on particular system or application.
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Modulation: representation
Any modulated signal can be represented as
s(t) = A(t) cos [wct + f(t)]
s(t) = A(t) cos f(t) cos wct - A(t) sin f(t) sin wct
amplitude
in-phase quadrature
phase or frequency
Linear versus nonlinear modulation impact on spectral efficiency
Constant envelope versus non-constantenvelope
hardware implications with impact on power efficiency
Linear: Amplitude or phase
Non-linear: frequency: spectral broadening
(=> reliability: i.e. target BER at lower SNRs)
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AKM lecture notes onAKM/DigCom/Mod
Linear Modulation Techniques
s(t)=[Sang(t-nT)]cos wct-[S bng(t-nT)] sin wct(t), in-phase Q(t), quadrature
LINEAR MODULATIONS
CONVENTIONAL
4-PSK
(QPSK)
OFFSET
4-PSK
(OQPSK)
DIFFERENTIAL
4-PSK
(DQPSK, p/4-DQPSK)
M-ARY QUADRATURE
AMPLITUDEMOD.(M-QAM)
M-ARY PHASE
SHIFT KEYING(M-PSK)
M 4 M 4M=4(4-QAM = 4-PSK)
Square
Constellations
Circular
Constellations
n n
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Generic Digital ModulatorsASK
AM
FSKVCOV1 and V2
BPSKMixer-V and +V
M-ary
DSPSource: Tomasi Electronic Comm
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AKM lecture notes onAKM/DigCom/Mod
PAM Circuits
Modulation
DetectionPeak detection, AM
http://www.tpub.com/content/neets/14184/css/14184_175.htm
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Binary
Amplitude Shift Keying
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Frequency Shift Keying
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Simple FSK Circuit
http://www.edn.com/contents/images/101101di.pdf
Transceivershttp://jap.hu/electronic/rf.html
http://www.edn.com/contents/images/101101di.pdfhttp://jap.hu/electronic/rf.htmlhttp://jap.hu/electronic/rf.htmlhttp://www.edn.com/contents/images/101101di.pdf -
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Phase Shift Keying
Binary
QuadratureM-ary
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Comparison of Modulation Techniques
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Power and Bandwidth Efficiency
Power efficiencyrefers to the ability of the modulation technique
to retain the message fidelityeven at low power level. Normally,the signal power needs to be increased to improve fidelity.
Tradeoff between fidelity and signal powerPower efficiency describes how efficient this tradeoff is
made
Eb: signal energy per bit N0: noise power spectral density P: Error probability
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Bandwidth efficiency refers to the ability of a modulation scheme to
accommodate data within a limited bandwidth. It indicates how
efficiently the allocated bandwidth is utilized
R: the data rate (bps) B: bandwidth occupied by the modulated RF signal
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Tradeoff Between Bandwidth Efficiency and Power Efficiency
Adding error control codes
Improves the power efficiency -Reduces the requires receivedpower for a particular bit error rateDecreases the bandwidth efficiency -Consumes more
bandwidth.
M-ary keying modulationIncreases the bandwidth efficiencyDecreases the power efficiency - More power is requires at the
receiver
M-FSK keying modulationIncrease the power efficiencyDecrease the bandwidth efficiency
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Shannons Upper Limit on Bandwidth
The fundamental upper limit on bandwidth efficiency may be
achieved using Shannons theorem (1948) that relates thechannel bandwidth with the maximum data rate that can be
transmitted over a noisychannel.
Shannons Theorem:
C: channel capacity (maximum data-rate) in bps,B: RF bandwidth S/N: signal-to-noise ratio
AKM/DigCom/Mod AKM lecture notes on
Example:SNR for a wireless channel is 30dB and RF bandwidth is 200kHz. Compute the
theoretical maximum data rate that can be transmitted over this channel.Solution:
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AKM lecture notes onAKM/DigCom/Mod
Condition ForError Free Communications as per
Shanons Formula
Required channel quality
for error free communications
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Bandwidth ExpressionsBandwidth depends on whether the signal is at baseband or at Passband. For
baseband, Bandwidth = (1/2)Rb(1 + ) (using a Nyquist LPF )For passband digital signal, Bandwidth = Rb(1 + ) (using Nyquist BPF)
NOTE: Symbol Rate that is key to bandwidth, not the Bit RateDifferent modulation schemes pack different no. of bits in a single symbol. BPSKhas 1
bit per symbol, QPSKhas 2 bits per symbol.
AKM/DigCom/Mod AKM lecture notes on
Occupied Bandwidth, B = Rs ( 1 + ) where Rs is the symbol rateand is the filter roll-off factor
Noise Bandwidth, BN, for a channel will not be affected by the roll-off factor of filter. Thus BN= Rs
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ExampleGIVEN:QPSK modulation, Bit rate 512 kbit/s, Filter roll-off, =0.3FIND: Occupied Bandwidth, B, and Noise Bandwidth, BN
SOLUTION:
Symbol Rate = Rs = (1/2) (512 103) = 256 103Occupied Bandwidth, B = Rs (1 + )=256 103 ( 1 + 0.3) = 332.8 KHz
Noise Bandwidth is, BN = Rs = 256 kHzSame Example with FEC: We use 1/2-rate FEC.
Symbol Rate, Rs = (1/2) (2) (512 103) = 512 103 symbols/s
Occupied Bandwidth, B = Rs ( 1 + ) = 665.6 kHz
2 bits per
symbolNumber of
bits/s
2 bits per
symbol 2-rateFEC
Number of
bits/s
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DetectionCoherent Detection
Local oscillatorSynchronizationRF carrier
Mixer, LPF; PLL
Incoherent Detection
No local oscillatorEnvelope detector; DiscriminatorDifferential PSK
ComparisonReceiver Circuits
S/NTiming
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Coherent and Non-coherent Detection
Coherent Detection (most PSK, some FSK):Exact replicas of the possible arriving signals are available at thereceiver.This means knowledge of the phase reference (phased-locked).Detection by cross-correlating the received signal with each one of
the replicas, and then making a decision based on comparisons withpre-selected thresholds.
Non-coherent Detection (some FSK, DPSK):Knowledge of the carriers wave phase not required.Less complexity.Inferior error performance.
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Coherent Detection
ASKFSKPSK
Source: Tomasi Electronic Comm
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Coherent Detection
Carrier RecoveryNo carrier pilotSquare loopCostas loop
RemodulatorReferencehttp://www.mwrf.com/Art
icles/Print.cfm?Ad=1&Articl
eID=9366
http://www.mwrf.com/Articles/Print.cfm?Ad=1&ArticleID=9366http://www.mwrf.com/Articles/Print.cfm?Ad=1&ArticleID=9366http://www.mwrf.com/Articles/Print.cfm?Ad=1&ArticleID=9366http://www.mwrf.com/Articles/Print.cfm?Ad=1&ArticleID=9366http://www.mwrf.com/Articles/Print.cfm?Ad=1&ArticleID=9366http://www.mwrf.com/Articles/Print.cfm?Ad=1&ArticleID=9366 -
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Design Trade-offs
Primary resources:Transmitted Power.Channel Bandwidth.
Design goals:Maximum data rate.
Minimum error probability.Minimum transmitted power.Minimum channel bandwidth.Robust against interfering signals.Minimum circuit complexity.
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Coherent Binary PSK (BPSK)
Two signals, one representing 0, the other 1.
Each of the two signals represents a single bit of information.Each signal persists for a single bit period (T) and then may be replaced by
either state.
Signal energy (ES) = Bit Energy (Eb), given by:
Therefore
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BPSK representation
Lets consider the unidimensional base (N=1) where:
Lets also rewrite the signal amplitudes as a function of their
energy:
AKM/DigCom/Mod AKM lecture notes on
Therefore, we can write the signals s1(t) and s2(t) in terms
of 1(t):
This can be graphically
represented by signal
space diagram as:
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BPSK Modulation
-A
+A
AKM/DigCom/Mod AKM lecture notes on
Noise consideration in BPSK Detection
Actual BPSK signal is received with noise
AWGN is a good approximation of noiseOther noise models are more complex
Constellation becomes a distribution because of noisevariations to signal
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Bit Error Rate (BER) for BPSK
BER is given by
Eb/No(dB) BER
0 0.082 0.044 0.0146 0.00278 2*10-410 4*10-610.543 10-6
Approximationvalid for Eb/Nogreater than ~4 dB
Note that these calculations are for synchronous detection
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erfc(z)= complementary error function of z = 1-erf(z)=
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Non-Coherent Modulation: DPSK
Information in MPSK, MQAM carried in signal phase.Requires coherent demodulation: i.e. phase of the transmitted signal carrier 0 must
be matched to the phase of the receiver carrier More cost, susceptible to carrier phase drift.Harder to obtain in fading channels
Differential modulation: do not require phase reference.More general: modulation with memory: depends upon prior symbolstransmitted.Use previous symbol as the a phase reference for current symbol
Information bits encoded as the differential phase between current & previoussymbolLess sensitive to carrier phase drift (f-domain) ; more sensitive to doppler effects:decorrelation of signal phase in time-domain
Differential PSKSimplicity
TransmitterReceiver
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DPSK
A 0 bit is encoded by no change in phase, whereas a 1 bit is encoded as a phase change of.
If symbol over time [(k1)Ts, kTs) has phase (k 1) = eji, i= 0, ,
then to encode a 0 bit over [kTs, (k+ 1)Ts), the symbol would have
phase: (k) = ejiand
to encode a 1 bit the symbol would have
phase (k) = ej(i+).DQPSK: gray coding:
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Coherent Quaternary PSK (QPSK)Four signals are used to convey information. This leads to a constellation of:
when shown as a phasor with reference to the signal phase, q,Each of thetwo states represents a two-bit information.
Constant Modulus =>
AKM/DigCom/Mod AKM lecture notes on
we use the following ortho-normal basis:
This gives, (after some trigonometricmanipulations), the constellation
representation or Signal space diagram
of coherent QPSK
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QPSK Implementation
Note that the QPSK
signal can be seen tobe two BPSK signalsin phase quadrature
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QPSK Detection
Resources for DetectionMini Circuitshttp://www.minicircuits.com/pages/app_notes.htmlIntel
http://www.intel.com/netcomms/technologies/wimax/303788.pdf
AKM/DigCom/Mod AKM lecture notes on
Bit Error Rate (BER) for QPSKThe BER is the probability of choosing the wrong signal (symbol) stateBecause the signal is Gray coded the BER for QPSK is that for BPSK:BER (after a lot of derivation) is given by:
Approximationvalid for Eb/Nogreater than ~4 dBNote that Eb is here, not Es!
http://www.minicircuits.com/pages/app_notes.htmlhttp://www.minicircuits.com/pages/app_notes.htmlhttp://www.intel.com/netcomms/technologies/wimax/303788.pdfhttp://www.intel.com/netcomms/technologies/wimax/303788.pdfhttp://www.intel.com/netcomms/technologies/wimax/303788.pdfhttp://www.intel.com/netcomms/technologies/wimax/303788.pdfhttp://www.minicircuits.com/pages/app_notes.htmlhttp://www.minicircuits.com/pages/app_notes.html -
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QPSK Waveform
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d li d d l i ( )
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Ak x
cos(2pfct)
Yi(t) =Akcos(2pfct)
Bk x
sin(2pfct)
Yq(t) = Bksin(2pfct)
+ Y(t)
Yi(t) and Yq(t) both occupy the bandpass channel QAM sends 2 pulses/Hz
Quadrature Amplitude Modulation (QAM)
QAM uses two-dimensional signalingAkmodulates in-phase cos(2pfct)
Bkmodulates quadrature phase cos(2pfct+ p/4) = sin(2pfct)Transmit sum of inphase & quadrature phase components
Transmitted
Signal
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QAM D d l i
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QAM Demodulation
Y(t) x
2cos(2 fct)2cos2(2 fct)+2Bk cos(2 fct)sin(2 fct)
= Ak{1 + cos(4 fct)}+Bk{0 + sin(4 fct)}
Lowpassfilter(smoother)
Ak
2Bksin2(2 fct)+2Ak cos(2 fct)sin(2 fct)
= Bk{1 - cos(4 fct)}+Ak{0 + sin(4 fct)}
x
2sin(2 fct)
BkLowpassfilter(smoother)
smoothed to zero
smoothed to zero
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Si l C ll i P
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Signal Constellation PatternsEach pair (Ak, Bk) defines a point in the plane
Signal constellation is a set of signaling points
4 possible points per Tsec.
2 bits / pulse
Ak
Bk
16 possible points per Tsec.
4 bits / pulse
Ak
Bk(A, A)
(A,-A)(-A,-A)
(-A,A)
AKM/DigCom/Mod AKM lecture notes on
Ak
Bk
4 possible points per Tsec.
Ak
Bk
16 possible points per Tsec.
Point selected by amplitude & phase
Akcos(2pfct)+Bksin(2pfct)= Ak2+Bk2cos(2pfct+tan-1(Bk/Ak))
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QAM Constellations
Euclidean Distance
Constellation Displayhttp://www.lecroy.com/tm/library
/LABs/PDF/LAB303B.pdf
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http://www.lecroy.com/tm/library/LABs/PDF/LAB303B.pdfhttp://www.lecroy.com/tm/library/LABs/PDF/LAB303B.pdfhttp://www.lecroy.com/tm/library/LABs/PDF/LAB303B.pdfhttp://www.lecroy.com/tm/library/LABs/PDF/LAB303B.pdf -
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M-PSK and M-QAM
M-PSK (Circular Constellations)
16-PSK
an
bn4-PSK
M-QAM (Square Constellations)
16-QAM
4-PSK
an
bn
Tradeoffs
Higher-order modulations (M large) are more spectrallyefficientbut less power efficient (i.e. BER higher).
M-QAM is more spectrally efficient than M-PSK butalso more sensitive to system nonlinearities.
O h M d l i S h
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Other Modulation SchemesOffset QPSK (OQPSK)
One of the bit streams delayed by Tb/2
Same BER performance as QPSKMinimum Shift Keying (MSK)
QPSK - also constant envelope, continuous phase FSK
minimum bandwidth, sidelobes large
1/2-cycle sine symbol rather than rectangular
Same BER performance as QPSK
can be implemented using I-Q receiverGaussian MSK (GMSK)
-- Reduces sidelobes of MSK using a pre-modulation filter
Used by RAM Mobile Data, GSM, CDPD, and HIPERLAN
AKM/DigCom/Mod AKM lecture notes on
http://www.emc.york.ac.uk/reports/linkpcp/appD.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://www.ictp.trieste.it/~radionet/2001_school/lectures/fitton/digital_mod.pdfhttp://www.plextek.com/papers/schmsv6.pdf
http://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://www.ictp.trieste.it/~radionet/2001_school/lectures/fitton/digital_mod.pdfhttp://www.ictp.trieste.it/~radionet/2001_school/lectures/fitton/digital_mod.pdfhttp://www.plextek.com/papers/schmsv6.pdfhttp://www.ictp.trieste.it/~radionet/2001_school/lectures/fitton/digital_mod.pdfhttp://www.plextek.com/papers/schmsv6.pdfhttp://www.plextek.com/papers/schmsv6.pdfhttp://www.ictp.trieste.it/~radionet/2001_school/lectures/fitton/digital_mod.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-976High-Speed-Communication-Circuits-and-SystemsSpring2003/D5DCBE3A-60CD-48A6-977E-78BD8CBEF42E/0/proj2.pdfhttp://www.emc.york.ac.uk/reports/linkpcp/appD.pdf 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Minimum Shift Keying (MSK) spectra
AKM lecture notes on Modulation
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AKM lecture notes onAKM/DigCom/Mod
System Performance
Eye DiagramSuperposition of sampled pulses
Eye OpeningContrast between 0 and 1http://www.complextoreal.com/chapters/eye.pdf
http://www.complextoreal.com/chapters/eye.pdfhttp://www.complextoreal.com/chapters/eye.pdf -
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Summary of Digital Communications Parameters
M = modulation size. Bw= Bandwidth in Hertz = Roll-off factor (from 0 to 1)
Gc = Coding Gain (convert from dB to linear) Ov= Channel Overhead (0 to1)Bits per Symbol: Symbol Rate [symbol/second]
Gross Bit Rate [bps]:
Net Data Rate [bps]:
Required Eb/No (using coding gain):
Required C/N:
Required Signal Strength [Watts]:
Where ,k = Boltzman constant = 1.38e-23 J/HzTS = System Noise TemperatureT0 = ambient temperature (usually 290 K)F = System Noise figure in linear scale (not in dB)
AKM lecture notes on ModulationAKM/DigCom/Mod
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