Data Comm - Bab 3 (Analog & Digital)

04/12/23 DDC2233 - Komunikasi Data 1

ISYARAT ANALOG & DIGITAL

Setelah tamat bab ini, anda boleh:- Menerangkan pengkodan & pemodulatan Membezakan jenis2 pertukaran isyarat Membincangkan perbezaan antara bps dan baud


Analog VS Digital Pengkodan (Encoding) & Pemodulatan

(Modulating) Digital-to-digital Digital-to-analog

Bps VS Baud Analog-to-digital Analog-to-analog


Analog ~ sesuatu yg selanjar (continuous) ~ “a set of specific points of data and all possible point between.”

Digital ~ sesuatu yg diskret (discrete) ~ “a set of specific points of data with no other points in between.”

Istilah digital dan analog digunakan pada 3 konteks komunikasi data iaitu: Data ~ maklumat / mesej yg dihantar Isyarat ~ gelombang elektrik / elektromagnetik yg

membawa dan mewakilkan data Sistem penghantaran ~ bagaimana infrastruktur /

komponen komunikasi data ‘melayan’ isyarat dlm media penghantaran.


Data yg berbentuk diskret (sifat unsur yg jelas berasingan atau bersendirian)

Data yg disimpan dalam ingatan komputer dlm bentuk 0s dan 1s. Ia selalunya ditukarkan dalam isyarat digital apabila diubah dari satu tempat ke tempat lain di dalam atau di luar komputer.

Contoh: rententan aksara, teks, nombor


Data yg bersifat selanjar (continuous) Suara manusia merupakan contoh data

analog. Apabila seseorang bercakap, gelombang selanjar tercipta di dlm udara. Ianya boleh direkodkan oleh mikrofon dan ditukarkan ke dalam isyarat analog.

Contoh: suara, audio dan video


Maklumat atau data yg melalui media penghantaran adalah disalurkan dalam bentuk isyarat elektrik atau gelombang elektromagnet yg dikenali sebagai isyarat analog dan digital.

Isyarat analog & digital terdiri drp 2 bentuk:- Periodic Aperiodic (nonperiodic)


Isyarat periodic mengandungi corak yg sama berulang2.

Sesuatu isyarat dinamakan isyarat periodic sekiranya ia dapat menghabiskan sesuatu corak dlm tempoh masa tertentu (period) dan mengulangi corak yg sama berulang2.

Satu corak penuh yg dihabiskan dikatakan “cycle”.


Isyarat yg berubah2 tanpa mengikuti corak tertentu.

Ia tidak mengandungi corak yg berulang2. Mana2 isyarat aperiodic boleh diuraikan ke

dlm beberapa isyarat periodic. Ianya telah dibuktikan oleh teknik yg dinamakan Fourier Transform.


Isyarat analog boleh dikelaskan kepada: Simple Composite

Simple analog signal juga dikenali sbg gelombang sine tidak boleh diuraikan ke dalam isyarat yg lebih mudah.

Composite analog signal mengangdungi beberapa gelombang sine.


Isyarat voltan atau arus yg berubah dengan licin dan berterusan, dan boleh mempunyai lebih daripada dua nilai asas.

Ia diwakili oleh gelombang sine. Gelombang sine boleh digambarkan oleh 3

ciri:- Amplitude Period atau frekuensi phase


Nilai setiap isyarat pd mana2 titik di atas gelombang.

Amplitud merujuk kepada ketinggian isyarat Unit kepada amplitude bergantung kpd jenis

isyarat. Bagi isyarat elektrik, ia boleh diukur dlm unit

volts, ampheres atau watts Volts (voltage) Amperes (current) Watts (power)


Period merujuk kpd tempoh masa (dalam saat) yang diperlukan bagi isyarat melengkapkan satu pusingan.

Frekuensi merujuk kpd bilangan period dlm masa 1 saat

Frekuensi sesuatu isyarat adalah bilangan kitaran yang dilakukan oleh isyarat dalam masa 1 saat

Unit utk period diukur dlm second (s), millisecond (ms), microsecond (s), nanosecond (ns) dan picosecond (ps).

Unit utk frekuensi diukur dlm hertz (Hz), kilohertz KHz), megahertz (MHz), gigahertz (GHz) dan terahertz (THz).



Ia menggambarkan kedudukan bentuk gelombang pada masa 0.

Ia disukat dlm degree atau radian


Isyarat elektrik yg bersifat diskret yg mempunyai dua aras khusus utk mewakili dua keadaan logik perduaan.

Ia diwakili oleh gelombang segi empat


Bit interval

Bit rate (bps)= # bit interval

time

(sec)

am

plit

ud

e (

volt

s)

Isyarat data yang diwakili oleh isyarat digital akan dikodkan sebagai 1 bagi mewakili voltan positif manakala kod 0 bagi mewakili voltan sifar

Isyarat digital digambarkan oleh bit interval (menggantikan period) dan bit rate (menggantikan frekuensi).

Bit interval merupakan masa yg diambil utk menghantar 1 bit.

Bit rate jumlah bit interval dlm 1 saat. Bilangan bit yg

dihantar dalam masa 1 saat. Ukuran unit adalah bits per second (bps).


Bit interval

Amplitudbit rate = 8bps

1 saat = 8 bit interval

Penukaran data digital ke isyarat digital dikenali sebagai digital-to-digital conversion atau encoding digital data into digital signal (pengekodan)

Penukaran data analog ke isyarat digital dikenali sbg analog-to-digital conversion atau digitizing an analog signal (pendigitalan)

Penukaran data digital ke isyarat analog dikenali sbg digital-to-analog conversion atau modulating a digital signal (permodulatan)

Penukaran data analog ke isyarat analog dikenali sbg analog-to-analog conversion atau modulating an analog signal.


IsyaratData

Digital Analog

Digital (I)Pengekodan

Data

(II)Permodulatan

Analog (III)Pendigitalan

(IV)Penyesuaian

Isyarat



+15Volt

0 1 0 1 0

-15Volt0 0 1 01

Pengekodan data

pemodulatan

Pendigitalan data analog


Pengulang

Selepas satu jarak

Penguat

Digital

Analog

Kualiti data yang lebih baik Mudah dikenalpasti data asal

Boleh membawa pelbagai jenis data dalam satu kabel

Gabungan dengan komputer Dapat membangunkan sistem yang lebih

canggih dan boleh dipercayai


Kelebaran spektrum frekuensi yang membolehkan transmisi

Perbezaan ant. frekuensi t’tinggi dan fre. Terendah Jika spektrum=300 hingga 3400Hz, lebar jalur =3100Hz

(300hz lagi bertindak sebagai ‘guardband’) Semakin besar lebar jalur semakin besar kosnya Lebar jalur yang terhad mudah berlaku gangguan Analog diukur dalam Hertz, digital diukur dalam

baud


Kelajuan maksima satu-satu saluran penghantaran adalah dua kali lebar jalurnya.

B = 2WB = kelajuan dalam baudW = lebar jalur dalam hz04/12/23 DDC2233 - Komunikasi Data 24

Bps = bilangan bit pada satu saat Baud = jumlah bilangan perubahan isyarat

pada satu saat Setiap perubahan isyarat boleh mewakili

lebih daripada satu bit, dengan melihat variasi amplitud, frekuensi atau phasa


Data mesti dikodkan kepada isyarat sebelum dihantar kepada destinasi.

Proses pengkodan data ini bergantung kepada format data asal dan format yang digunakan oleh perkakasan komunikasi.


Pengkodan digital-kepada-digital (hanya akan dibincangkan skema pengkodan manchester )

Pengkodan analog-kepada-digital (disentuh lebih lanjut dalam bab pendigitlan)

Pengkodan digital-kepada-analog (disentuh lebih lanjut dlm bab modulation)

Pengkodan analog-kepada-analog (disentuh lebih lanjut dlm bab modulation)


Host Pengkodan jenis ini mewakili maklumat digital melalui isyarat digital

Contoh: apabila data dipindahkan daripada komputer kepada pencetak

Dalam pengkodan jenis ini, binari 1 dan 0 yang dikeluarkan daripada komputer diterjemahkan kepada arus nadi voltan


Unipolar – pengkodan hanya menggunakan satu aras nilai Polar – menggunakan dua aras amplitud (positif dan negatif),

terbahagi 3 kategori1. Non Return Zero (NRZ)

1. Non Return Zero level (NRZ-L)2. Non Return Zero Inversion (NRZ-I)3. Return Zero (RZ)

2. Biphase 1. Manchester2. Differential Manchester

Bipolar – menggunakan tiga aras : positif, kosong, dan negatif., 3 variasi:-

1. AMI

2. B8ZS

3. HDB304/12/23 DDC2233 - Komunikasi Data 29

3 kategori umum:- Unipolar encoding Polar encoding

NRZ NRZ-L NRZ-I

RZ Biphase

Manchester Differential Manchester

Bipolar AMI B8ZS HDB3


Very simple and very primitive. Digital transmission systems work by sending voltage

pulses along a medium link, usually a wire or cable. In most types of encoding, one voltage level stands for

binary 0 and another level stands for binary 1. Unipolar encoding uses only one level of value. I.e: 1s are encoded as a positive value and the 0s are

encoded as the zero value.


Amplitude

Time

0 0 0 01 1 1 1

It uses two voltage levels (positive & negative) of amplitude.

Three most popular polar encoding: Nonreturn to zero (NRZ) Return to zero (RZ) biphase


The level of the signal is always either positive or negative.

The two most popular methods of NRZ transmission are: Nonreturn to zero, level (NRZ-L) Nonreturn to zero, invert (NRZ-I)



Tinggi+ve

Rendah-ve

01 01 01 1 0

Tinggi untuk 0,Rendah untuk 1

The level of the signal depends on the type of bit it represents.

A positive voltage usually means the bit is a 0, and a negative voltage means the bit is a 1.

The level of the signal is dependent upon the state of the bit.


Amplitude

Time

0 0 0 01 1 1 1

The signal is inverted if a 1 bit is encountered. It is the transition between a positive and a

negative voltage, not the voltages themselves, that represents 1 bit.

A 0 bit is represented by no change, and 1 bit change the signal.


Amplitude

Time

0 0 0 01 1 1 1

Perwakilan bit 0 dan 1 ditentukan oleh isyarat sebelumnya dan bukannya oleh perwakilan tetap elektrik. Bit 1 akan menukar paras voltan sebelumnya dan bit 0 akan mengekalkan paras voltan sebelumnya


Tinggi+ve

Rendah-ve

01 01 01 1 0

It uses three values (positive, negative and zero) The signal changes not between bits but during

each bit. A 1 bit represented by positive-to-zero and a 0

bit by negative-to-zero.


Amplitude

Time

0 0 0 01 1 1 1

The signal changes at the middle of the bit interval but does not return to zero.

It continues to the opposite pole There are two types of biphase encoding:

Manchester (method used by Ethernet LANs) Differential Manchester (used by Token Ring)



It uses the inversion at the middle of each bit interval for both synchronization and bit representation.

A negative-to-positive transition represents binary 1 and a positive-to-negative transition represents binary 0.


Setiap bit data yang dihantar ada perubahan isyarat Ditengah satu isyarat, arah voltan akan berubah dari

+ve -ne @ sebaliknya Bit ditentukan oleh permulaan voltan

bit 0 ~ bermula dgn voltan tinggi kemudian berubah kpd voltan rendah di pertengahan isyarat

bit 1 ~bermula dgn voltan rendah kemudian berubah kpd voltan tinggi di dipertengahan isyarat



1 1 1 10 0 0 0

The inversion at the middle of the bit interval is used for synchronization, but the presence or absence of an additional transition at the beginning of the interval is used to identify the bit.

A transition means binary 0 and no transition means binary 1.

It requires two signal changes to represent binary 0 but only one to represent binary 1.


Voltan sebelumnya menentukan isyarat. Bit 0, berlaku perubahan isyarat Bit 1, tiada perubahan isyarat



Andaikan, voltan sebelumnya adalah +ve

0 0 0 11 1 1 0

It uses three voltage levels (positive, negative and zero) The zero level is used to represent binary 0 The 1s are represented by alternating positive and

negative voltages. If the first 1 bit is represented by the positive amplitude,

the second will be presented by the negative amplitude, the third by the positive amplitude, and so on.


Amplitude

Time

0 0 0 01 1 1 1

Three types of bipolar encoding are in popular use by the data communications industry: Bipolar Alternate Mark Inversion (AMI) Bipolar 8-Zero Substitution (B8ZS) High-Density Bipolar 3 (HDB3)


AMI means alternate 1 inversion. A neutral, zero voltage represents binary 0. Binary 1s are represented by alternating

positive and negative voltages.


Amplitude

Time

0 0 0 01 1 1 1

B8ZS functions identically to bipolar AMI The difference between B8ZS and bipolar AMI occurs

whenever eight or more consecutive 0s are encountered in the data stream.

Anytime eight 0s occur in sucession, B8ZS intoduces changes in the pattern based on the polarity of the previous 1 (the 1 occuring just before the 0s).

If the previous 1 bit was positive, the eight 0s will be encoded as 0,0,0,+ve,-ve,0,-ve,+ve.

If the previous 1 bit was negative, the eight 0s will be encoded as 0,0,0,-ve,+ve,0,+ve,-ve.



1 0 0 0 0 0 0 0 0 0 0 1 0 0Amplitude

Time

+ 0 0 0 0 0 0 0 0

+ 0 0 0 + - 0 - + - 0 0 0 - + 0 + -

- 0 0 0 0 0 0 0 0

Polarity of previous b

it

It introduces changes into the bipolar AMI pattern every time four consecutive 0s are encountered instead of waiting for the eight expected by B8ZS.

If four 0s come one after another, we change the pattern in one of four ways based on the polarity of the previous 1 and the number of 1s since the last substitution.


1 0 0 0 0 0 0 0 0 0 0 1 0 0Amplitude

Time


1 0 0 0 0 0 0 0 0 0 0 1 0 0Amplitude

Time

+ 0 0 0 0

- 0 0 0 - + - 0 0 - - + 0 0 +

+ 0 0 0 0- 0 0 0 0 - 0 0 0 0

+ 0 0 0 +

If the number of 1s since the last substitution is odd

If the number of 1s since the last substitution is even

Lakarkan isyarat digital untuk jujukan bit 0010100010 menggunakan skema pengekodan NRZ dan NRZI. Anggapkan isyarat sebelumnya adalah positif


1. Lakarkan perwakilan bit menggunakan kaedah pengengkodan NRZ, Manchester dan Differential Manchester untuk jujukan bit 10110100.

2. Apakah jujukan bit untuk perwakilan graf dibawah untuk skema pengekodan manchester dan skema differential manchester?


Tinggi+ve

Rendah-ve

Also known as digital-to-analog modulation The process of changing one of the

characteristics of an analog signal based on the information in a digital signal (0s and 1s)

Data from one PC to another across a public access phone line must be converted.

The original data are digital, but because the telephone wires carry analog signals, the data must be converted.

Modem is used to convert digital-to-analog signals.



Before we discuss specific methods of digital-to-analog modulation, two basic issues must be fined: Bit/baud rate Carrier signal


Bit rate ~ the number of bits transmitted during one second (bps).

Baud rate ~ the number of signal units per second that are required to represent those bits.

Baud rate determines the bandwidth required to send the signal.

Bit rate = baud rate * # bits for each signal Baud rate = bit rate / # bits for each signal


Bit rate is always greater or equal to the baud rate.

Baud rate always less or equal to the bit rate. i.e. in transportation:-

Baud = car Bit = passenger

A car can carry one or more passengers. If 1000 cars go from one point to another carrying only 1 passenger (driver), then 1000 passengers are transported. If each car carries 4 passenger, then 4000 passengers are transported.


Note: # of cars, not the # of passengers, determines the traffic and, therefore, the need for wider highways.

Similarly, the # of bauds determines the required bandwidth, not the number of bits.


Analog signal carries 4 bits in each signal element. If 1000 signals elements are sent per second, find the baud rate and the bit rate. Baud rate = # of signal elements = 1000 baud/s Bit rate = baud rate X # bits per signal elements = 1000 X 4 = 4000 bps


The bit rate of a signal is 3000. If each signal element carries 6 bit, what is the baud rate? Baud rate = bit rate / # of bits per signal = 3000 / 6 = 500 baud per second


In analog transmission, the sending device produces a high-frequency signal that acts as a basis for the information signal.

This base signal is called the carrier signal or carrier frequency.

Digital information is modulated on the carrier signal by modifying one or more of its characteristics (amplitude, frequency, phase).

This kind of modification is called modulation (or shift keying) and the information signal is called a modulating signal.


Amplitude shift keying (ASK) / Amplitude Modulation (AM)

Frequency shift keying (FSK) / Frequency Modulation (FM)

Phase shift keying (PSK) / Phase Modulation (PM)

Quadrature amplitude modulation (QAM)


Bit 0 dan 1 diwakilkan dengan membezakan ketinggian amplitud pada satu-satu unit isyarat analog.

Contohnya bit 0 akan ditinggikan sehingga 15v dan bit 1 akan ditinggikan hanya setinggi 8v.

Rajah perwakilan jujukan bit 011000110000 kaedah AM.


0 0 0 0 0 0 0 01 1 1 1


Bit 0 dan 1 diwakilkan dengan membezakan jumlah frekuensi pada satu-satu unit isyarat.

Contohnya bit 0 akan menggunakan frekuensi sebanyak 150Hz, dan bit 1 akan menggunakan frekuensi sebanyak 225 Hz.

Rajah perwakilan jujukan bit 0110001 melalui kaedah FM.


0 0 0 01 1 1


Bit 0 dan 1 diwakilkan dengan membezakan fasa isyarat.

Perubahan fasa adalah tempat permulaan gelombang sinus

Terdapat dua teknik pemodulatan fasa: PSK (Phase Shift Keying) dan DPSK (Differential PSK)



Perubahan fasa menandakan perubahan bit. Contohnya, jika bit 0 bermula dengan fasa 0o, bit seterusnya

akan terus diwakilkan oleh fasa 0o jika bit seterusnya adalah 0. jika bit seterusnya adalah 1, maka perubahan fasa sebanyak

180o digunakan. Rajah perwakilkan jujukan bit 011000110000 (dengan

menganggap bit sebelumnya adalah bit 0 dengan fasa 0o)


Bit 0 diwakilkan dengan tiada perubahan fasa daripada sebelumnya.

Setiap kali bit 1 hendak diwakilkan, perubahan fasa sebanyak 180o akan dilakukan.

Rajah perwakilan bit 011000110000 dengan DPSK


Bps ~ jumlah bit yang dihantar dalam satu (1) saat

Baud ~ bilangan unit isyarat dalam satu saat Satu isyarat mungkin membawa lebih

daripada satu bit. (dibit, tribit, quadbit, pentabit, hexabit, septabit, octabit) Dibit = 2 bit dalam satu unit isyarat Tribit = 3 bit dalam satu unit isyarat

> 1 bit dlm 1 isyarat memerlukan perwakilan unit isyarat yg mencukupi




01 00 10 11

Kitar900

Kitar00

Kitar1800

Kitar2700

Lakarkan penghantaran secara dibit untuk jujukan data berikut 1010110100 melalui kaedah dibit PM


10 10 11 01 00

Menggabungkan ASK dan PSK utk menghasilkan lebih banyak perwakilan paras tanpa merapatkanya (bit, dibit, tribit, quadbit, dll).

Bila lebih banyak bit dalam satu unit isyarat, yang lebih banyak paras isyarat perlu disediakan.

Bila lebih banyak paras isyarat, perbezaan antara satu paras dengan paras yang lain semakin dekat


positif

negatif

000 011 100 110001 010 101 111


01 00 10 11

Kitar900

Kitar00

Kitar1800

Kitar2700

kemungkinan isyarat. Dapat hantar duabit data dalam setiap isyarat

000 010 100 101

Fasa 900

AM-T

4PM & 2AM - menghasilkan 8 kemungkinan isyarat. Dapat hantar tiga bit datadalam setiap isyarat

Fasa 900

AM-SFasa 00

AM-TFasa 00

AM-SFasa 1800

AM-TFasa 1800

AM-SFasa 2700

AM-TFasa 2700

AM-S

001 011 110 111

4PM & 1AM - menghasilkan 4



00 01 11 10 00 10 01



00 01 11 10 00 10 01

Also known digitizing analog signals Sometimes analog signals need to be

digitized. i.e. to send human voice over a long

distance, we need to digitize it since digital signals are less affected to noise.

The information contained in the continuous wave form is converted into a series of digital pulses (1s and 0s).

Codec (coder-decoder) is used for converting analog to digital signals.



Data analog perlu didigitalkan terlebih dahulu utk membolehkan ianya menggunakan sistem penghantaran digital.

Pendigitalan data analog akan menghasilkan data digital.

Data ini seterusnya akan dibawa oleh isyarat digital atau isyarat analog.

Pendigitalan menghasilkan data yang sangat banyak.


Methods used in digitizing an analog signal: Pulse Amplitude Modulation (PAM) Pulse Code Modulation (PCM)

PAM has some applications, but it is not used by itself in data communication.

PAM is the first step in another conversion method called PCM.


This technique takes an analog signal, samples it, and generates a series of pulse on the results of the sampling.

Sampling means measuring the amplitude of the signal at equal intervals.

It uses a technique called sample and hold. At a given moment, the signal level is read, then

held briefly. The sample value occurs only instantaneously in

the actual wave form, but is generalized over a still short but measurable period in the PAM result.



PAM only translates the original wave form to a series of pulase and these pulses are still of any amplitude (still analog, not digital).

PCM modifies the pulse created by PAM to create a completely digital signal.

PCM first quantizes the PAM pulse. Quantization is a method of assigning

integral values in a specific range to sampled instances.



It uses a simple method of assigning sign and magnitude values to quantized samples.

Each value is translated into its seven-bit binary equivalent. The eight bit indicates the sign.

The binary digits are then transformed into a digital signal using one of the digital-to-digital encoding techniques.



PCM is actually made up of four separate processes PAM Quantization Binary encoding Digital-to-digital encoding

I.e. PCM is the sampling method used to digitize voice in T-line transmission in the USA.



Bil bit terhasil sesaat = bil sampel sesaat X bil bit sesampel

Kualiti pendigitalan: Telefon: 8,000 sampel sesaat dengan 8 bit

sesampel Muzik: 32,000 sampel sesaat dengan 16 bit

sesampel. CD: 44,000 sampel sesaat dengan 32 bit

sesampel.


Bil bit terhasil sesaat = bil bingkai sesaat X resolusi satu bingkai

Kualiti pendigitalan: TV: lebih kurang 30 bingkai sesaat Resolusi skrin komputer lebih kurang 800 X 600

pixel (anggapkan satu pixel bersamaan satu bit)


Lakarkan penghantaran untuk jujukan data berikut 10111001 melalui kaedah Manchester dan Differential Manchester (andaikan voltan sebelumnya adalah +ve 15 volt). Dengan menggunakan jujukan data yang sama, lakarkan penghantaran melalui kaedah dibit dalam PM.


Kirakan jumlah bit yang terhasil utk mendigitalkan satu lagu, selama 4.5 minit, pada kualiti CD?

Berapa lamakah masa diperlukan utk memuat-turun (download) lagu tersebut menggunakan modem V.90?


Anggapkan lima minit klip video hendak dihantar melalui talian telefon, menggunakan modem berkelajuan 56 Kbps. Klip video ini didigitalkan utk paparan satu skrin penuh berresolusi 680 X 480 pixel, dengan bilangan bingkai sebanyak 30 bingkai sesaat. Kelajuan data berkesan talian ini adalah 60%. Menggunakan kelajuan data berkesan, kirakan masa yg diambil utk menghantar klip video digital tersebut.


The representation of analog information by an analog signal.

Analog information can be converted directly into an analog signal that occupies the same bandwidth, i.e. voice.

Voice generated sound waves in the range of 300 to 3400 Hz can be represented by an electromagnetic signal with the same frequency components.

This signal can then be directly transmitted on a voice-grade telephone line.


It is also possible to use an analog signal to modulate a carrier to produce a new analog signal that conveys the same information but occupies a different frequency band.

Analog-to-analog modulation can be accomplished in 3 ways:- Amplitude modulation (AM) Frequency modulation (FM) Phase modulation (PM)



In AM, the carrier signal is modulated so that its amplitude varies with the changing amplitudes of the modulating signal.

The frequency and phase of the carrier remain the same, only the amplitude changes.


In FM, the frequency of the carrier signal is modulated to follow the changing voltage level (amplitude) of the modulating signal.

The peak amplitude and phase of the signal remain constant, but as the amplitude of the information signal changes, the frequency of the carrier changes correspondingly.


PM is used in some systems as an alternative to FM.

In PM transmission, the phase of the carrier signal is modulated to follow the changing voltage level (amplitude) of the modulating signal.

The peak amplitude and frequency of the carrier signal remain constant, but as the amplitude of the information signal changes, the phase of the carrier changes correspondingly.

The analysis and the final result (modulated signal) are similar to those frequency modulation.


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Data Comm - Bab 3 (Analog & Digital)