A/L ICT Competency 8.3

Nju;rr ; p 8.3 mbg;gil Fwpg;Ngw;w EZf;fq;fs; (Modulation) mbg;gil Fwpg;Ngw;wkhdJ Fiwe;j J}uj;jpw;F gpuahzpf;ff; $ba miy nfhz;l rkpq;iQahdJ fhtpr;rkpq;iQfSld; (Carrier Signal) ,izf;fg;gl;L $Ljyhd J}uj;jpw;F gpuahzpf;f; $ba cau; miy nfhz;l rkpq;iQfshf khw;wg;gl;L gupkhw;wj;jpw;F jahu; nra;ag;gLk; ,k;khw;Wk; nraw;ghNl Fwpg;Ngw;wk; (Modulation) vdg;gLk;.

Fwpg;Ngw;wk; (Modulation)

xg;Gik miy(Analog Signal)

vz;zpay; miy(Digital signal)

(jho; - cau; miytupir)

(vz;zpay; - xg;Gik)

Amplitude Modulation (AM)

Amplitude Shift Key (ASK)

Frequency Modulation (FM)

Frequency Shift Key (FSK)

Phase Modulation (PM)

Phase Shift Key (PSK)

Fwpg;Ngw;wr; nraw;ghL (Modulation) xg;Gik miy rkpq;iQ

F

Fwpg;Ngw;wg;gl;l rkpq;iQ

Fwpg;Ngw;wp (Modulator)

Carrier Signal fhtpr;rkpq;iQ (vg;nghOJk; cau; xg;Gik miytupir)

fhtpr; rkpq;iQ (Carrier Signal) fhtpr; rkpq;iQ vd;gJ kpf cau; kPbuidf; nfhz;l rf;jp tha;e;j kpd;fhe;j miyfshFk; (Electro magnet wave). ,J rhjhuz Fuy; miyfis gupkhw;wk; nra;Ak; NghJ mf;Fuy; miyfis mjpf J}uk; gpuahzk; nra;aj;jf;fjhf khw;w mf;Fuy; miyfSld; fhtpr; rkpq;iQfis cs;sPlhf toq;fp mitapuz;ilAk; Fwpg;Ngw;wp ePz;l J}u gpuahzj;jpw;F jahu; nra;ag; gad;gLk;.

xg;Gik rkpq;iQia Fwpg;Ngw;wg;gLk;.

Fwpg;Ngw;Wk;

NghJ

miyapd;

%d;W

gz;Gfspid

mbg;gilahff;

nfhz;L

1. Amplitude Modulation (AM) ,f;Fwpg;Ngw;wkhdJ miyapDila gyj;jpy; khw;wk; Vw;gLj;JtjpD}lhf ,lk;ngWk;. mjhtJ me;j rkpq;iQapd; voltage or gpufhrj;jpy; khw;wk; nra;tjpD}lhf ,f; Fwpg;Ngw;wk; ,lk;ngWk;. ,jid gpd;tUk; glk; tpgupf;fpd;wJ.

- fhtpr; rkpq;iQ

- Fwpg;Ngw;w rkpq;iQ - Fwpg;Ngw;wg;gl;l rkpq;iQ

2. Frequency Modulation (FM) ,e;j Fwpg;Ngw;wkhdJ miytupirapd; kPbudpy (Frequency) khw;wj;jpid Vw;gLj;JtjpD}lhf ,lk;ngWk;. ,jid gpd;tUk; glk; tpgupf;fpd;wJ

- fhtpr; rkpq;iQ

- Fwpg;Ngw;w rkpq;iQ - Fwpg;Ngw;wg;gl;l rkpq;iQ

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3. Phase Modulation (PM) ,J miytupirapd; ,aw;if Xl;lj;ij jw;fhypfkhf jhkjpg;gjd; Clhf ngw;Wf; nfhs;sg;gLfpd;wJ. mjhtJ fhtp rkpq;iQfSf;F nghUj;jkhd miyapd; Njhw;wj;ij ,lkhw;Wtjd; %yk; ,J ngw;Wf; nfhs;sg;gLk;. ,jid ,g;; glk; tpgupf;fpd;wJ

rkpq;iQfshdJ xg;Gik Kiwfspy; Fwpg;Ngw;wg;Lk;. Digital 1.

fhtpr;

-fhtpr; rkpq;iQ -

-Fwpg;Ngw;w rkpq;iQ

- Fwpg;Ngw;wg;gl;l rkpq;iQ

rkpq;iQAld;

Nru;j;J

FwpapLk;

NghJ

gpd;tUk;

Amplitude Shift Key (ASK) ,e;j Fwpaplypd; NghJ xg;Gik fhtpr;rkpq;iQahdJ Fwpaplg;gLk; rkpq;i ; QfSf;F Vw;g khWgLk; mNj neuk; mjDila tPr;rk; kw;Wk; mtj;ij khwJ ,Uf;Fk;. ,jpy; tPr;rkhdJ Jtpj ju;f;f ,yf;fq;fshd 0,1 ,dhy; gpujpepjpj;Jtg;gLj;jg;gLk;. ,jid gpd;tUk; glk; tpgupf;fpd;wJ

2. Frequency shift key (FSK) ,f;Fwpaplypd; NghJ fhtpr;rkpq;iQahdJ Fwpaplg;gLk; rkpq;iQapd; kPbuDf;F Vw;g mjDila tPr;rk;, mtj;ij khwhjpUf;f fhtpr;rkpq;iQapd; kPbud; khWk;. ,jid gpd;tUk; glk; tpgupf;fpd;wJ

3. Phase shift key (PSK) ,J fhtpr; rkpq;iQapd; mtj;ijapy; khw;wk; Vw;gLj;JtjpD}lhf khw;wg;gLk;. ,jid gpd;tUk; glk; tpgupf;fpd;wJ.

xg;Gik rkpq;iQia vz;zpay; rkpq;iQf;F khw;wy;  

,jid khw;Wtjw;fhd Kiwahf pulse code Modulation (PCM) gad;gLj;jg;gLfpd;wJ gpd;tUk; %d;W gbKiwfSf;Fl;gl;Nl ,e;j khw;wk; epfopfpdwJ.

1. Step 1- Sampling Sample

 



2|ILM.Irfan

xg;Gik rkpq;iQapdJ shine tisapahdJ epiyf;Fj;jhf gpupf;fg;gLk;. ,jd; xU gFjp sample MFk;. xU Rw;wpy; vj;jid sample ,Uf;f Ntz;Lk; vd;gJ sampling Theorum %yk; (Nyquist Theorum) jPu;khdpf;fg;gLk;.

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(xU nrf;fDf;Fs;shd Sample fspd; vz;zpf;if)

Sampling Rate

≥

2 X Mff;$ba kPbud; (Highest Frequency) cjhuzk;: kPbud; 0.3 – 3.4 KHz cila miytupirapd; samplefspd; vz;zpf;if Sampling Rate ≥ 2 X Mff;$ba kPbud; (Highest Frequency) = 2 X 3.4 khz = 6.8 khz (,jid fpl;ba 2d; klq;fpw;F kl;lk; jl;ly;) = 8 khz = 8000 Hz/s

2. Step 2 – Quantizing Quantizing kl;lk 52

52

;

0

0



Quantizing kl;lkhdJ mjpfkhf ,Ue;jhy; me;j rkpq;iQahdJ ek;gfkhdJ.

3. Step 3 – Encoding 

,jpy; xt;nthU kl;lKk; encode gz;zg;gLk;.

cjhuzkhf sample quantizing kl;lkhdJ 52 vd;why; mJ binary f;F khw;wg;gLk;. ,J 8 bit y; vOjg;gLk;

0

0

1

1

0

1

0

0

CODEC (Compressor and Decompresser or Coder and Decoder) CODEC MdJ Digital data stream or rkpq;iQia encode or decode gz;z gad;gLj;jg;gLk; xU rhjdk; or xU fzdp epuypahFk;.. ,f; CODEC MdJ data sream or rkpq;iQfis gupkhw;wj;jpw;fhf, Nrkpg;gjw;fhf or Nghypf;FwpapLtjw;fhf encode gz;Zk, or mtw;wpypUe;J gpw NjitfSf;fhf decode gz;Zk

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