number of phases are used. In the case of FSK, a finite number of frequencies are used. In the case of ASK, a finite number of **amplitudes** are used. Digital **Modulation** Digital **Modulation** Formats ASK PSK FSK **Amplitude** **Shift** **Keying** (ASK) The most basic (binary) form of ASK involves the process of switching the carrier either on or off, in correspondence to a sequence of digital/

3*1000 /2 = 1500Hz. 5&3 not necessary to equal. 17Sec3_Dig_Modu Phase **Shift** **Keying** (PSK). Angle – **modulated**, constant – **amplitude** digital **modulation**. Analog input Binary digital signal PM PSK Limited number of output phase Binary PSK (BPSK) two phases also called /=2 M=2 = 4 N=3 M=2 = 8 3 1 2 27Sec3_Dig_Modu Quaternary Phase **Shift** **Keying** (QPSK) = M=4 QASK angle-**modulated**, constant – **amplitude**. Digital **modulation**. QPSK 1 one carrier & 4 different phases. 2-bits 4 input conditions 4 output phasesQPSK /

M-ary digitally **modulated** carriers **Amplitude** **Shift** **Keying** (ASK) A binary information signal directly **modulates** the **amplitude** of an analog carrier. Sometimes called Digital **Amplitude** **Modulation** (DAM) Where v ask (t) = **amplitude** **shift** **keying** wave v m (t) = digital information signal (volt) A/2 = unmodulated carrier **amplitude** (volt) ω c = analog carrier radian frequency (rad/s) Digital **Amplitude** **Modulation** Frequency **Shift** **Keying** (FSK) Called as Binary Frequency **Shift** **Keying** (BFSK) The phase **shift** in carrier/

.Digital-to-Analog Conversion 2.**Amplitude** **Shift** **Keying** (ASK) 3.Frequency **Shift** **Keying** (FSK) 4.Phase **Shift** **Keying** (PSK) 5.Quadrature **Amplitude** **Modulation** (QAM) 6.Bit/Baud Comparison 7.Modems Digital-to-analog **modulation** Types of digital-to-analog **modulation** Aspects to digital-to Analog /signal unit carries 6 bits, what is the baud rate? Baud rate = 3000/6 =500 bauds/sec **Amplitude** **Shift** **Keying** (ASK) The strength of the carrier signal is varied to represent binary 1 and 0. Frequency and phase remains/

→ “dense” → more signal states/symbol → more information/Hz !! ∴ Bandwidth Efficient IV. Linear **Modulation** Methods In linear **modulation** techniques, the **amplitude** of the transmitted signal varies linearly with the **modulating** digital signal. Performance is evaluated with respect to Eb / No BPSK BPSK → Binary Phase **Shift** **Keying** Phase transitions force carrier **amplitude** to change from “+” to “−”. **Amplitude** varies in time BPSK RF signal BW Null-to-null RF BW = 2/

occur in discrete steps using binary signals – Uses same three basic types of **modulation** as analog **Amplitude** **shift** **keying** (ASK) CWNA Guide to Wireless LANs, Second EditionCCRI J. Bernardini 39 Digital **Modulation** Frequency **shift** **keying** (FSK) Phase **shift** **keying** (PSK) CWNA Guide to Wireless LANs, Second Edition 40 Quadrature phase **shift** **keying** (QPSK) CWNA Guide to Wireless LANs, Second Edition 41 Physical Layer Standards (continued) Figure 4-21: 16-level quadrature/

occur in discrete steps using binary signals Uses same three basic types of **modulation** as analog **Amplitude** **shift** **keying** (ASK) CWNA Guide to Wireless LANs, Second EditionCCRI J. Bernardini CWNA Guide to Wireless LANs, Second EditionCCRI J. Bernardini Digital **Modulation** Frequency **shift** **keying** (FSK) Phase **shift** **keying** (PSK) CWNA Guide to Wireless LANs, Second EditionCCRI J. Bernardini Quadrature phase **shift** **keying** (QPSK) CWNA Guide to Wireless LANs, Second Edition 16-QAM/

will be m = Vmo/Vco. If m =0.5, the carrier **amplitude** varies by 50 % . If m= 1.0 then it varies by 100%. **Modulation**: **Amplitude**-**Shift** **Keying** (ASK) ASK encodes digital data by **modulating** the carriers **amplitude** between two or more levels. Suppose a signal with **amplitude** 1 represents a binary 0 and a signal with **amplitude** 2 represents a binary 1. AM is more sensitive to noise/

) + 2) * 5 t) Q: Is the constant “2" necessary here? 13 13 **Modulation** of Digital Signals A different term: **shift** **keying** Instead of a continuum of possible values, digital **shift** **keying** has a fixed set Mapping to the power levels of a digital signal a carrier wave a digital input signal **amplitude** **shift** **keying** frequency **shift** **keying** Exercise: ASK Consider the input signal with 3 levels shown above. Assume we/

Pe,QPSK = Q[√(2 EB / N0)] RB – Bit rate, TB – Bit period EB – Energy/bit, N0 – Noise spectral density QPSK BW = RB = 1 / TB Nonlinear or envelope **modulation** Frequency **shift** **keying** The frequency of a constant **amplitude** carrier signal is switched between 2 values ( 1 and 0) Properties of FSK Transmission Bandwidth BT = 2f + 2B B = Bandwidth of digital base-band signal If/

signal unit carries 6 bits, what is the baud rate? Solution Baud rate = 3000 / 6 = 500 baud/s ASK Describe **Amplitude** **Shift** **Keying** ASK Describe **Amplitude** **Shift** **Keying** **Amplitude**-**shift** **keying** (ASK) is a form of **modulation** that represents digital data as variations in the **amplitude** of a carrier wave.**modulation** digitaldataamplitudecarrier wave The simplest and most common form of ASK operates as a switch, using the presence of a carrier wave/

signals in the voice-frequency range Topic 4 –Data Encoding and Modulation18 Digital Data, Analog Signals **Modulation** involves operation on one or more of the characteristics of a carrier signal: **amplitude**, frequency, and phase **Modulation** techniques for transforming digital data onto analog signals –**Amplitude** **Shift** **Keying** (ASK) –Frequency **Shift** **Keying** (FSK) –Phase **Shift** **Keying** (PSK) In all these cases, the resulting signal occupies a bandwidth centred on the carrier frequency/

( 1, # Decimation rate chan_taps, #coefficients 0, #Offset frequency - could be used to **shift** 48e3) #incoming sample rate 29 Outline r Recap r **Amplitude** demodulation m frequency **shifting** m low pass filter r Digital **modulation** 30 r **Modulation** of digital signals also known as **Shift** **Keying** r **Amplitude** **Shift** **Keying** (ASK): m vary carrier amp. according to data r Frequency **Shift** **Keying** (FSK) o vary carrier freq. according to bit value r Phase/

information 05 - Winter 2005 ECE ECE 766 Computer Interfacing and Protocols 2 **Modulation** **Modulation** Techniques –**Amplitude** **Shift** **Keying** (ASK) –Frequency **Shift** **Keying** (FSK) –Phase **Shift** **Keying** (PSK) Aspects of **Modulation** –Bit rate vs. Baud rate Bit rate ≥ Baud rate –Carrier Signal Quadrature **Amplitude** **Modulation** (QAM) 05 - Winter 2005 ECE ECE 766 Computer Interfacing and Protocols 3 **Amplitude** **Shift** **Keying** (ASK) Basic technique (like AM) change the **amplitude** of the signal to transfer logical values On-Off/

(x) + mi ] * sin (35x) a = 0.3, mi =1 16 17 **Modulation** of Digital Signals A different term: **shift** **keying** – Instead of a continuum of possible values, digital **shift** **keying** has a fixed set Mapping to the power levels of a digital signal **Amplitude** **Shift** **Keying**: Example 18 Carrier: 2 sin(2 4 t) Digital input signal: **Modulated** carrier: 2V level “1” 1V level “0” Exercise: ASK Consider the/

a square wave. 2-3: Sidebands and the Frequency Domain Figure 1-12: **Amplitude** **modulation** of a sine wave carrier by a pulse or rectangular wave is called **amplitude**-**shift** **keying**. (a) Fifty percent **modulation**. (b) One hundred percent **modulation**. 2-3: Sidebands and the Frequency Domain Pulse **Modulation** Continuous-wave (CW) transmission can be achieved by turning the carrier off and on, as in Morse code transmission/

original value. If m= 1.0 then it varies by 100%. **Modulation**: **Amplitude**-**Shift** **Keying** (ASK) ASK encodes digital data by **modulating** the carriers **amplitude** between two or more levels. Suppose a signal with **amplitude** 1 represents a binary 0 and a signal with **amplitude** 2 represents a binary 1. AM is more sensitive to noise than other **modulation** techniques => AM is not widely used in data transmission . A/

a square wave. 2-3: Sidebands and the Frequency Domain Figure 1-12: **Amplitude** **modulation** of a sine wave carrier by a pulse or rectangular wave is called **amplitude**-**shift** **keying**. (a) Fifty percent **modulation**. (b) One hundred percent **modulation**. 2-3: Sidebands and the Frequency Domain Pulse **Modulation** Continuous-wave (CW) transmission can be achieved by turning the carrier off and on, as in Morse code transmission/

, changes occur in discrete steps using binary signals – Uses same three basic types of **modulation** as **Amplitude** **shift** **keying** (ASK) REFERENCES CCRI Engineering and Technology Jbernardini 44 Frequency vs. Phase **Shift** **Key** **Modulation** CCRI Engineering and Technology Jbernardini 44 Frequency **shift** **keying** (FSK) Phase **shift** **keying** (PSK) REFERENCES CCRI Engineering and Technology Jbernardini 45 Throughput vs. Data Rate CCRI Engineering and Technology Jbernardini 45 Data Rate = Total Data Rate through system/

a square wave. 2-3: Sidebands and the Frequency Domain Figure 1-12: **Amplitude** **modulation** of a sine wave carrier by a pulse or rectangular wave is called **amplitude**-**shift** **keying**. (a) Fifty percent **modulation**. (b) One hundred percent **modulation**. 2-3: Sidebands and the Frequency Domain Pulse **Modulation** Continuous-wave (CW) transmission can be achieved by turning the carrier off and on, as in Morse code transmission/

the carrier signal 8The receiving modem translates the analog signal back into digital data Methods of **Modulation** 8Amplitude **modulation** (AM) or **amplitude** **shift** **keying** (ASK) 8Frequency **modulation** (FM) or frequency **shift** **keying** (FSK) 8Phase **modulation** or phase **shift** **keying** (PSK) **Amplitude** **Shift** **Keying** (ASK) 8In radio transmission, known as **amplitude** **modulation** (AM) 8The **amplitude** (or height) of the sine wave varies to transmit the ones and zeros 8Major disadvantage is that telephone lines are very susceptible/

plot at left T8A01 - Which of the following is a form of **amplitude** **modulation**? A. Spread-spectrum B. Packet radio C. Single sideband D. Phase **shift** **keying** 10Modes T8A01 - Which of the following is a form of **amplitude** **modulation**? A. Spread-spectrum B. Packet radio C. Single sideband D. Phase **shift** **keying** 11Modes T8A02 - What type of **modulation** is most commonly used for VHF packet radio transmissions? A. FM/

signal **Amplitude**-**shift** **keying** (ASK) **Amplitude** difference of carrier frequency Frequency-**shift** **keying** (FSK) Frequency difference near carrier frequency Phase-**shift** **keying** (PSK) Phase of carrier signal **shifted** Basic Encoding Techniques **Amplitude**-**Shift** **Keying** One binary digit represented by presence of carrier, at constant **amplitude** Other binary digit represented by absence of carrier where the carrier signal is Acos(2πf c t) **Amplitude**-**Shift** **Keying** Susceptible to sudden gain changes Inefficient **modulation**/

M significantly higher BER - smaller distances in constellation - sensitive to timing jitter MPSK MQAM MFSK OFDM Combined Linear & Constant Envelope **Modulation** 3 Mary Phase **Shift** **Keying** Carrier phase takes 1 of M possible values – **amplitude** constant i = 2(i-1) /M, i = 1,2,…M **Modulated** waveform: s i (t) = 0 t T s, i = 1,2,…M E s = log 2 M E b/

1 Digital to Analog Encoding 2 3 Digital **modulation** techniques **Amplitude** **Shift** **Keying** **Amplitude** **Shift** **Keying** Frequency **Shift** **Keying** Frequency **Shift** **Keying** Phase **Shift** **Keying** Phase **Shift** **Keying** Quadrature **Amplitude** **Modulation** (QAM) Quadrature **Amplitude** **Modulation** (QAM) 4 **Amplitude** **Shift** **Keying** ASK ASK –The strength of carrier signal varies (the **amplitude** changes) –The frequency and phase remain constant –The speed of transmission is limited by the physical characteristics of the transmission media –/

removed from DC (like optical) is called a bandpass channel Transmission on a bandpass channel requires **modulation** of a carrier **Amplitude** **Shift** **Keying** (ASK) Phase **Shift** **Keying** (PSK) Frequency **Shift** **Keying** (FSK Quadrature **Amplitude** **Modulation** (QAM) **Amplitude** **Shift** **Keying** (ASK) **Amplitude** of carrier wave is **modulated** Equivalent BER vs SNR to baseband PAM Proakis and Salehi, pp. 306 Angle **Modulation** (PSK and FSK) Frequency is time derivative of phase, PSK and FSK are somewhat equivalent Proakis/

.13 The total bandwidth required for PM can be determined from the bandwidth and maximum **amplitude** of the **modulating** signal: B PM = 2(1 + β)B. Note 5.14 Digital **Modulation** Digital **modulation** is used to generate analog signals from information bit streams Digital **modulation** types **Amplitude** **Shift** **Keying** Frequency **Shift** **Keying** Phase **Shift** **Keying** Quadrature **Amplitude** **Modulation** 5.15 Digital **modulation** is the process of changing one of the characteristics of an analog signal based/

four zeros replaced with one or two pulses B8ZS and HDB3 Digital Data, Analog Signal ÑPublic telephone system Ñ300Hz to 3400Hz ÑUse modem (**modulator**-demodulator) Ñ**Amplitude** **shift** **keying** (ASK) ÑFrequency **shift** **keying** (FSK) ÑPhase **shift** **keying** (PK) **Modulation** Techniques **Amplitude** **Shift** **Keying** ÑValues represented by different **amplitudes** of carrier ÑUsually, one **amplitude** is zero Ñi.e. presence and absence of carrier is used ÑSusceptible to sudden gain changes ÑInefficient ÑUp to 1200bps on voice/

progress. Straight **Key** Keyer “Bug” Keyer **Amplitude** **Modulation** Changes the instantaneous power in the radio wave in time with a **modulating** signal. The strength (**amplitude**) of the carrier signal is made to vary in accordance with the audio signal. **Modulation** Envelope Audio /tones, corresponding to mark and space, are sent to the mic input when the radio is **keyed**. This is called Audio Frequency **Shift** **Keying** (AFSK), but is indistinguishable from FSK. RTTY Tuning Aid Packet Radio Computer to computer mode that/

have become very important in wired and wireless communications To send data by radio, higher frequency carrier waves are necessary **Amplitude**, frequency, and phase are all used in digital communication systems Frequency-**Shift** **Keying** The simplest form of digital **modulation** in current use is frequency-**shift** **keying** (FSK) In its simplest form two frequencies are generated, one corresponding to a binary zero (space) and the other/

to that of Analogue transmission. Fundamental digital **modulation** methods: Binary **Amplitude** **shift** **keying** (on-off **keying**) advantage: simplicity disadvantage: ASK is very susceptible to noise interference– noise usually (only)affects the **amplitude**, therefore ASK is the **modulation** technique most affected by noise application: ASK is used to transmit digital data over optical fiber Frequency **Shift** **Keying** Frequency **Shift** **Keying** (FSK) is a frequency **modulation** scheme (conveys information over a carrier wave/

Learning Objectives Upon completing this **module**, you should be able to: 1. Recognize periodic functions. 2. Determine the **amplitude** and period, when given the equation of a periodic function. 3. Find the phase **shift** and vertical **shift**, when given the equation /. Step 2: Sketch the two vertical asymptotes found. x = /4. Step 3:Divide the interval into four equal parts. This gives the following **key** x-values. First quarter: − /8 Middle value: 0Third quarter: /8 42 Rev.S08 How to Graph y = tan(2x)? /

for AM, with or without **modulation**. The duty cycle for SSB is about 20 to 25% and 0% without **modulation**. Angle **Modulated** Modes –Frequency **Modulation** (FM) varies the frequency in proportion to the signals **amplitude**. –Phase **modulation** (PM) varies the phase (time **shift**) of the signal. –FM /the 5 bit Baudot code. On HF, most RTTY signals are 45 baud and use a 170 Hz **shift** between mark and space. Multiple-frequency **shift** **keying** (MFSK16) uses 16 separate tones separated by 15.625 Hz. This fits within a 500 Hz CW/

COMMUNICATION Lecture-17 Recap of Lecture 16 Analog-To-Digital Conversion Pulse Code **Modulation** (PCM) – Pulse **Amplitude** **Modulation** (PAM) – Quantization – Binary Encoding – Digital-to-Digital Conversion Overview of Lecture 17 Digital-to Analog Conversion Bit Rate and Baud Rate Carrier Signals **Amplitude** **Shift** **Keying** (ASK) Frequency **Shift** **Keying** (FSK) Phase **Shift** **Keying** (PSK) Quadrature **Amplitude** **Modulation** (QAM) Digital To Analog Conversion Process of changing one of the characteristics of/

01 00 10 cos-sin -cos-sin CS 515 © Ibrahim Korpeoglu Constant Envelope **Modulation** **Amplitude** of the carrier is constant, regardless of the variation in the **modulating** signal Better immunity to fluctuations due to fading. Better random noise immunity Power efficient They occupy larger bandwidth CS 515 © Ibrahim Korpeoglu Frequency **Shift** **Keying** (FSK) The frequency of the carrier is changed according to the message state/

signal-to-noise ratio than standard diode detectors. 4-3: **Amplitude** Demodulators Synchronous Detection The **key** to making the synchronous detector work is to ensure that the /**Amplitude** Demodulators Figure 4-22 A practical synchronous detector. 4-4: Balanced **Modulator** A balanced **modulator** is a circuit that generates a DSB signal, suppressing the carrier and leaving only the sum and difference frequencies at the output. The output of a balanced **modulator** can be further processed by filters or phase-**shifting**/

Analog Encoding: Process of changing one of the characteristics of an analog signal based on the digital signal (1 or 0). It has following types: 1.**Amplitude** **Shift** **Keying** (ASK) 2.Frequency **Shift** **Keying** (FSK) 3.Phase **Shift** **Keying** (PSK) 4.Quadrature **Amplitude** **Modulation** (QAM) Punjab EDUSAT Society33 Punjab EDUSAT Society ASK: Strength of the carrier signal is varied to represent binary 1 or 0. 34 Bandwidth for ASK/

modems, modem designers had to use techniques far more sophisticated than frequency- **shift** **keying**. In order to create faster modems, modem designers had to use techniques far more sophisticated than frequency- **shift** **keying**. First they moved to phase-**shift** **keying** (PSK), and then quadrature **amplitude** **modulation** (QAM). First they moved to phase-**shift** **keying** (PSK), and then quadrature **amplitude** **modulation** (QAM). These techniques allow an incredible amount of information to be crammed/

01 B8ZS 14 Digital Data, Analog Signal – ASK (1) **Amplitude** **Shift** **Keying** (ASK): Information111 100 0 T 2T2T 3T3T 4T4T5T5T 6T6T ASK t 15 Digital Data, Analog Signal – FSK (2) Frequency **Shift** **Keying** (FSK): Information111 100 0 T 2T2T 3T3T 4T4T5T5T 6T6T ASK t /in a stereo system. How much data will be generated in one hour? 22 Analog Data, Digital Signals – Delta **Modulation** (1) Delta **modulation** is a scheme used to improve the performance of PCM. An analog signal is approximated by a staircase function /

(0 and 1). 64/78 Digital to Analog **Modulation** 3.9 Digital-to-Analog Conversion Types of digital-to-analog **modulation** 65/78 Digital-to-Analog **Modulation** ASKFSKPSK QAM 3.9 Digital-to-Analog Conversion ASK (**Amplitude** **shift** **keying**) : **amplitude** of carrier signal FSK (Frequency **shift** **keying**) : frequency of carrier signal PSK (Phase **shift** **keying**) : phase of the carrier signal QAM (Quadrature **amplitude** **modulation**): phase+**amplitude** Bit rate is the number of bits per/

Long Waves, Medium Waves and Short Waves **Modulation** of Analog Signals **Amplitude** **Modulation** (AM) Frequency **Modulation** (FM) Phase **Modulation** (PM) Figure 5.24 Analog-to-analog **modulation** Types of analog-to-analog **modulation** **Amplitude** **modulation** (AM) Frequency **modulation** (FM) Phase **Modulation** (PM) Digital **modulation** Three basic methods – **Amplitude** **shift** **keying** (ASK) – Frequency **shift** **keying** (FSK) – Phase **shift** **keying** (PSK **Amplitude** **shift** **keying** (ASK) Use different **amplitude** to represent 0 and 1. – Simple/

signals, PM is considered a special form of FM Difference is clearer in digital **modulation** process 8 **Modulating** Digital Signals **Amplitude** **Shift** **Keying** (ASK) Frequency **Shift** **Keying** (FSK) Phase **Shift** **Keying** (PSK) Combinations of the above 9 ASK and FSK Carrier Digital Input ASK FSK 10 Phase **Shift** **Keying** (PSK) 0 o phase shift180 o phase **shift** 11 PSK Constellation Diagrams Constellation diagram is used to express the exact assignment of data/

two inputs -a carrier -and a signal To distinguish between analog and digital **modulation** -We use the term **shift** **keying** rather than **modulation** ASK is the abbreviation of **Amplitude** **Shift** **Keying** Ask is called On-Off **Keying**. The simplest and most common form of operate as a switch. It is Abbreviated as Frequency **shift** **keying** Values represented by different frequencies (near carrier) Less susceptible to error than ASK Typically used/

signal-to-noise ratio than standard diode detectors. 4-3: **Amplitude** Demodulators Synchronous Detection The **key** to making the synchronous detector work is to ensure that the /**Amplitude** Demodulators Figure 4-22 A practical synchronous detector. 4-4: Balanced **Modulator** A balanced **modulator** is a circuit that generates a DSB signal, suppressing the carrier and leaving only the sum and difference frequencies at the output. The output of a balanced **modulator** can be further processed by filters or phase-**shifting**/

the non-linearities of the emitter or of the channel in mobile communications. They are also more robust to fading than **modulation** using the carrier **amplitude** to carry information. PSK = Phase **Shift** **Keying** OQPSK = Offset Phase **Shift** **Keying** 16QAM = QAM **modulation** with 16 different states For **amplitude**-phase. Spectral efficiency can be defined as the number of bits per second that can be transmitted in 1 Hz bandwidth/

through a system in a given unit of time (bit rate bps) Hartley’s Law Shannon limit for information capacity **Amplitude**-**shift** **keying** (ASK) the binary information signal directly **modulates** the **amplitude** of an analog carrier there are only two output **amplitudes** possible mathematically written as Frequency-**shift** **keying** (FSK) mathematically written as when the binary input change logic from 1 to logic 0, the output frequency change/

data rate in bits per second? http://rfidsecurity.uark.edu 13 Gen-2 Reader-to-Tag Physical and Link Layers **Modulation** – Double sideband **amplitude** **shift** **keying** (DSB-ASK) – Single-sideband ASK (SSB-ASK) – Phase reversal ASK (PR-ASK) Encoding - Pulse interval/ energy reflected from tag to reader –80 to 90 dB less signal than reader-to-tag (10,000 times weaker!) **Modulation** –**Amplitude**-**shift** **keying** (ASK) –Phase-**shift** **keying** (PSK) Encoding – Reader chooses type –FM0 –Miller (M=2, 4, or 8) Data rates are variable /

Sinusoid of frequency fc is centered in middle of bandpass channel **Modulators** embed information into a sinusoid **Amplitude** **Modulation** and Frequency **Modulation** Information 1 +1 **Amplitude** **Shift** **Keying** t T 2T 3T 4T 5T 6T -1 Map bits into **amplitude** of sinusoid: “1” send sinusoid; “0” no sinusoid Demodulator looks for signal vs. no signal +1 Frequency **Shift** **Keying** t T 2T 3T 4T 5T 6T -1 Map bits into/

fc Use some combination of **amplitude**, phase, or frequency. MULTIMEDIA SYSTEMS IREK DEFEE **Amplitude**-**Shift** **Keying** (ASK) Change **amplitude** A CARRIER MULTIMEDIA SYSTEMS IREK DEFEE ASK (cont.) The signal is MULTIMEDIA SYSTEMS IREK DEFEE Phase-**shift** **Keying** (PSK) Change phase q /c@Irek Defée MULTIMEDIA SYSTEMS THERE ARE VERY MANY DETAILS IN ADSL STANDARD: HOW THE CARRIERS ARE **MODULATED**? (QAM **MODULATION**) HOW THE **MODULATION** IS REALIZED? (512-POINT FFT) HOW THE ERROR CORRECTION IS PERFORMED? (FEC) HOW THE SIGNALS /

stability. Also, PM is adaptable to data applications Examples of Phase **Shift** Bit Rate = Baud rate x Bits per Symbol PSK and QAM Phase **Shift** **Keying** (PSK) Most popular implementation of PM for data In BPSK (Binary PSK): one bit per phase change In QPSK: two bits per phase change (symbol) Quadrature **Amplitude** **Modulation** (QAM) Uses two AM carriers with 90o phase angle between them/

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