Slide Elka

7/29/2019 Slide Elka

1/47

ELEKTRONIKA TELEKOMUNIKASI

Universitas Mercu Buana

Fina Supegina, ST, MT


2/47

Tujuan Komunikasi Radio

Mengirimkan informasi dari sumber ke

tujuan (dapat berjauhan letaknya) dengan

memanfaatkan media udara sebagaisaluran transmisi


3/47

Bagan Komunikasi Radio Secara Umum

SUMBER TUJUAN

PEMANCAR (TX) PENERIMA (RX)


4/47

Bagian TX dan RX Tersusun Atas Bagian-bagian Berikut

Pemancar (TX)

SUMBER MODULATOR

OSCILLATOR

PENGUAT


5/47

Penerima (RX)

PENGUAT DEMODULATOR TUJUAN


6/47

Jika diperhatikan lebih lanjut,maka terdapat beberapa hal yangmenjadi perhatian, yaitu :

Modulator dan Demodulator (Detector)

Oscillator

Penguat

Modulasi (akan dibahas tersendiri) Antenna

Saluran Transmisi


7/47

Modulator

Berfungsi untuk memodifikasi sinyalpembawa (carrier) dari oscillator sesuaisistem modulasi yang digunakan

(pemodulasi)


8/47

Demodulator (Detector)

Berfungsi sebagai alat untuk mendapatkaninformasi yang terkandung dalam sinyalcarrier termodulasi

Rangkaian Demodulator tergantung jenismodulasi yang digunakan


9/47

Oscillator

Berfungsi sebagai Pembangkit SinyalPembawa (Carrier) pada Pemancar


10/47

Penguat (Amplifier)

Berfungsi memberikan penguatanterhadap sinyal yang akandikirim/diterima

Pada penerima, dapat berfungsi sebagaifilter karena karakteristik responsefrequency mirip band pass filter

Pada pemancar, berfungsi mengjilangkanharmonisa dari rangkaian-rangkaianpemancar


11/47

Antenna

Berfungsi meradiasikan gelombangelektromagnetik terbimbing padasaluran ke udara bebas

Masing-masing bentuk antenna punyapola pancaran (radiasi) yang berbeda


12/47

Saluran Transmisi

Agar daya sinyal dapat dipancarkansecara maksimal, maka impedansi outputrangkaian pemancar dengan impedansikarakteristik saluran transmisi, sertaimpedansi beban harus sama (match)

Jika tidak sama, maka akan terjadigelombang pantul

Jika komunikasi radio dipandang dalamkonteks saluran transmisi, maka dapatdigambarkan seperti berikut


13/47

Analogue Signals and Digital

Signals1. Analogue Signals

Analogue signals: These are usually

older electronic gadgets (introduced

before the mid 1990s). A goodexample of an analogue signal is the

loud-speaker of a stereo system.

When the volume is turned up the

sound increases slowly and

constantly.


14/47

Analogue Signals and Digital

Signals2. Digital Signals

Digital signals: Modern electronic

products such as computers and

mobile phones depend on digitalsignals. However, a good example

of a digital signal is Morse Code.

The signal is sent as a series of

on and off pulses. The signal is

either present or it is not.


15/47

Analog signal must be converted into Digitalform (Discrete) before DSP techniques canbe applied. The analog signal is basically

denoted asx

[t] orx

a[t] because it varied bytime. The analog signal comes in form ofsinusoid (sine or cosine wave).

The Analog signal is digitized by usingIntegrated Electronic Circuit device called anAnalog-to-Digital Converter (ADC). Theoutput of ADC will be in the form of binarynumber that represents the analog signal

such as electrical voltage.


16/47


17/47

The analog signal are always come with noise.

Thus the noise filtering is needed before the

signal goes to ADC. The filtering can be doneby using DSP techniques.

The special purpose microprocessors are

designed to carry out application of DSP. It is

named as Digital Signal Processors (DSPs)

and used in real time application.


18/47

DSPs are programmable devices and capable of carrying outmillions of instruction per second.

It is vital to know how Digital Signal Processing work before we go

to DSPs (The diagram of the process is shown in Figure 1 and 2).

The signals and systems must come together. The systems areneeded to operate the signals. For example, we need to useThermometer to measure Temperature, Microphone to carry outanalog signal (human voice) and convert it to electrical signal,

Charge-Couple Device (CCD) used in in Camera or Digital Camerato convert image to picture and so on. In general, the system ischaracterized by the type of operation that it performs on thesignal.


19/47

Figure 1 : Digitized process of signal


20/47

Figure 2 : Complete Process of Digital Signal


21/47

From the diagram, it can be seen that ADC and

DAC are 2 vital devices used in signal

processing to convert the signal from analog todiscrete (digital) and vice versa.

ADC is basically consists of Sampler, Quantizer

and Coder. All this elements are built up byCMOS Switched-Capacitor (for Sampling), Op-

Amp (Signal Amplification) & Comparator

(Quantizer).


22/47

Quantization is the conversion of discrete-time continuous-valued to discrete-timediscrete- valued (digital) signal. The

difference of this is called Quantization Error.

The coder in ADC will convert the output ofthe Quantizer to b-bit binary sequence that

can be read by DSPs (Digital SignalProcessors).

The DAC, will perform a reverse operation ofADC in order to generate back analog signal.


23/47

DSP CAN BE APPLIED IN THE FOLLOWING FIELDS :

=> COMMUNICATION SYSTEMS

(MOBILE PHONE, SATELLITE, RADAR, SONAR,INTERNET)

=> ENTERTAINMENT ELECTRONICS

(RADIO, TV, Hi-Fi, CD/VCD/DVD PLAYER,MP3),

=> MULTIMEDIA

(ACOUSTICS, IMAGE, SPEECH RECOGNIZATION&

VIDEO CODING, DIGITAL CAMERA),


24/47

=> MEDICAL INSTRUMENT

(ECG Electrocardiogram provides

information about the condition of patients heart),=> GEOPHYSICS (Seismology)

(Apparatus used to measure earth movement)

=> INSTRUMENTATION(ELECTRONIC TESTER Such as Digital Multimeter,

Oscilloscope)=> IC TECHNOLOGY

=> DATA COMPRESSION


25/47

Advantages of using digital filters

The following list gives some of the mainadvantages of digital over analog filters.

1. A digital filter isprogrammable, i.e. its

operation is determined by a program stored

in the processor's memory. This means thedigital filter can easily be changed without

affecting the circuitry (hardware). An analog

filter can only be changed by redesigning

the filter circuit.

2. Digital filters are easily designed, tested

and implementedon a general-purpose

computer.


26/47

3. The characteristics of analog filter

circuits (particularly those containing

active components) are subject to drift and

are dependent on temperature. Digitalfilters do not suffer from these problems,

and so are extremely stable with respect

both to time and temperature.


27/47

4. Unlike their analog counterparts, digitalfilters can handle low frequencysignals

accurately. As thespeed of DSP technology continues toincrease, digital filters are being applied tohigh frequency

signals in the RF (radio frequency) domain,which in the past was the exclusivepreserve of analog

technology.

5. Digital filters are very much moreversatile in their ability to process signals ina variety of ways; this includes the ability ofsome types of digital filter to adapt tochanges in the characteristics of the signal.


28/47

1. The analog signal are always come with ________2. DSP or digital signal processing is the __________of

the signals digitally or by digital means.

3. ADC is basically consists of_______, Quantizer andCoder.

4. The coder in ADC will _____the output of theQuantizer to b-bit binary sequence that can be read byDSPs (Digital Signal Processors).

5. Unlike their analog counterparts, digital filters canhandle____frequencysignals accurately

Test 1


29/47

NOISEPROCESSING

Sampler

ConvertLow


30/47

Test 1

What is the meaning of DSP ?

List the application of DSP ?

Electrical signal are in two form. What are

they ? List example of digital signals and

analogue signals?

Mention the advantages of using digitalfilters ?


31/47

Deret Fourier


32/47

Menurut Fourier setiap fungsi periodik

dapat dinyatakan sebagai jumlah fungsi

sinus dan cosinus yang tak berhingga

jumlahnya dan dihubungkan secaraharmonis. Maka, karena respons paksaan

terhadap setiap bentuk

sinusoida/cosinusoida dapat ditentukandengan mudah dengan konsep fasor.


33/47

Bentuk Trigonometris dari Deret Fourier

Mula-mula kita tinjau sebuah fungsi periodik f(t) yangdidefinisikan sebagai :

f(t) = f(t + T)

dengan T adalah perioda. Selanjutnya kita anggap bahwafungsi f(t) memenuhi sifat-sifat berikut :

f(t) berharga tunggal dimana, yakni f(t) memenuhi definisimatematis dari sebuah fungsi.

Integral ada (yakni, tidak tak berhingga) untuk

setiap pemilihan to

f(t) mempunyai diskontinuitas yang terbatas banyaknyadidalam setiap perioda

f(t) mempunyai maksimum dan minimum yang terbatasbanyaknya didalam setiap perioda.


34/47

. Dengan adanya fungsi periodik f(t) seperti itu, maka

teorema Fourier mengatakan bahwa f(t) dapat dinyatakan

dengan deret tak berhingga


35/47


36/47

GELOMBANG GENAP

GELOMBANG GENAP

f(t) = f(-t)


37/47

GELOMBANG GANJIL

f(t) = - f(-t)


38/47


39/47


40/47

Contoh :


41/47


42/47


43/47


44/47


45/47


46/47


47/47

Kisi-kisi

Sinyal, deret fourier

Osilator

Power amplifier

Modulasi, demodulasi, sistem rx n tx

Slide Elka

Documents

Transcript of Slide Elka