Nhung du lieu tren nen tin hieu am thanh

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TRNG I HC BCH KHOA H NI

VIN IN T - VIN THNG

N TT NGHIP

TI: Nhng d liu trn nn tn hiu m thanh

s dng cng ngh v tuyn nh ngha bng phn mm

Gio vin hng dn : TS. Trng Tun

Sinh vin inh Vn Nam 20091814 TVT 01 K54

H Ni, 12/2014

2

LI CM N

u tin, ti xin gi li cm n chn thnh v su sc nht ti TS Trng Tun,

ngi thy nhit tnh hng dn v truyn t nhng kin thc cn thit, ti hon

thnh ny.

Ti xin gi li cm n ti gia nh, chnh l ngun lc ng vin ti phn u

trong hc tp v cuc sng.

Ti cng xin cm n cc thy, c gio ca Vin in T Vin Thng, Trng i

hc Bch Khoa H Ni tn tnh dy d, ch bo ti trong sut nhng nm hc

trng.

Tuy c nhiu c gng trong qu trnh hc tp cng nh thi gian lm n nhng

khng th trnh khi nhng thiu st, ti rt mong c s gp qu bu ca tt c cc

thy c gio v cc bn n ca ti c hon thin.

Ti xin chn thnh cm n!!

H Ni, ngy 7 thng 1 nm 2015.

Sinh Vin

inh Vn Nam

3

Mc Lc.

Mc Lc..............................................................................................................................3

Bng cc ch ci vit tt, thut ng....................................................................................4

Danh mc cc hnh v........................................................................................................5

Danh mc cc bng biu ....................................................................................................6

Li m u ...................................................................................................................... ...7

CHNG 1. L Thuyt V K Thut Nhng Trn Nn Tn Hiu m Thanh.................9

1. Tng quan v k thut giu tin (k thut nhng)................................................9

1.1. S lc v lch s giu tin......................................................................9

1.2 Khi nim giu tin.................................................................................11

1.3 Phn loi cc k thut giu tin.............................................................12

1.4 Mc ch ca giu tin... ........................................................................14

1.5 Mi trng giu tin...............................................................................15

a. Giu tin trong nh (image)...........................................................15

b. Giu tin trong m thanh (audio)...................................................16

c. Giu tin trong phim (video) .........................................................17

2. Tp tin m thanh( file wav)................................................................................18

2.1 nh ngha File .Wav.........................................................................18

2.2 Cu trc File .Wav.............................................................................18

3. K thut giu tin trong m thanh( audio)...........................................................21

3.1 M hnh k thut giu tin trong m thanh (audio)..............................21

3.2. Mt s k thut giu tin trong m thanh (audio)...............................22

3.2.1. M ha LSB (Least Significant Bit)......................................22

3.2.2. M ha Parity (Parity Coding)...............................................23

3.2.3 M ha Phase (Phase Coding).................................................23

3.2.4. K thut tri ph.....................................................................25

3.3 Cc tn cng trn cc h giu tin...........................................................25

3.4 Yu cu k thut giu tin trong m thanh(audio).................................26

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4. Tm tt chng....................................................................................27

CHNG 2. Cng ngh v tuyn nh ngha bng phn mm....................................28

1. Gii thiu cng ngh v tuyn nh ngha bng phn mm SDR.................28

2. Cc ng dng ca h thng SDR...................................................................30

3. GNU Radio.....................................................................................................31

3.1 Cu trc GNU Radio..........................................................................33

3.2 GNU Radio Companion....................................................................35

3.3 Ci t phn mm GNU Radio.........................................................36

4. Gii thiu USRP B210...................................................................................37

4.1 Mt s tnh nng ca USRP B210.....................................................38

4.2 Cc thng s k thut USRP B210....................................................38

4.3 S khi ca USRP B210................................................................40

4.5 Kim tra USRP B210 trn nn LINUX..............................................40

4.6 Kt ni gia USRP B210 v GNU Radio...........................................41

5. Tm tt chng................................................................................................41

Chng 3 Xy Dng Chng Trnh Nhng D Liu Trn Nn Tn Hiu m Thanh..42

1. K Thut M Ha LSB....................................................................................43

2. Thut ton nhng d liu trn n m thanh s dng k thut m ha LSB...43

2.1 Tin x l thut ton giu v tch tin LSB..........................................44

2.2 Thut ton giu tin...............................................................................44

2.3 Thut ton tch tin................................................................................44

2.4 u im ca k thut m ha LSB.......................................................45

2.5 Nhc im ca k thut m ha LSB.................................................46

3. Ci t v th nghim chng trnh..................................................................46

3. 1. Mi trng ci t..............................................................................46

3.3 So snh ph bin ca m thanh trc v sau khi nhng d liu....50

3.4 nh gi v chng trnh....................................................................51

4. Xy dng m hnh truyn d liu......................................................................52

4.1 Giao thc TCP......................................................................................52

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4.2 Xy dng m hnh truyn d liu qua mng wifi...............................55

4.2.1 Thit lp my ch...................................................................55

4.2.2 Thit lp my khch................................................................55

5 Th nghim m hnh truyn thng tin b mt qua wifi....56

6 Tm tt chng..56

Chng 4. Kt lun............................................................................................................57

Ti Liu Tham Kho..........................................................................................................59

Ph Lc...................................................................................................................... ........60

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Bng cc ch ci vit tt, thut ng.

Vit tt Ting anh Ting vit

ADC Analog to Digital Converter B chuyn i tng t - s

AM Amplitude Modulation iu ch bin

BPSK Binary Phase Shift Keying Kha dch pha nh phn

DAC Digital Analog Converter B chuyn i s-tng t

DSSS Direct Sequency Spread

Spectrum

Phng php tri ph trc tip lin tc.

DCT Discrete Cosine Transform Bin i cosine ri rc

DSP Digital Signal Processor B x l tn hiu s

DWT Discrete Wavelet Transform Bin i sng ri rc

FFT Fast Fourier Transform Bin i Fourier nhanh

FHSS Frenquency Hopped Spread

Spectrum

Phng php tri ph nhy tn s

FIFO First In First Out Vo truc ra trc

FM Frequency modulation iu ch tn s

FPGA Field programmable Gate Array Mng cng lp trnh c dng trng

GSM Global System for Mobile

Communication H thng di ng ton cu

H thng di ng ton cu

HAS Human Auditory System H thng thnh gic

HVS Human Visual System H thng th gic ca con ngi

IFFT Inverse Fast Fourier Transform Bin i Fourier nhanh nghch

LSB Least Significant Bit Bit c trng s thp

MIMO Multiple-Input Multiple-Output H thng a anten pht v thu

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OFDM Orthogonal Frequency Division

Multiplexing

Ghp knh phn chia theo tn s trc

giao.

QAM Quadrature Amplitude

Modulation

Php iu ch bin QAM

QPSK Quadrature Phase Shift Keying

iu ch pha cu phng

QPSK Quadrature Phase Shift Keying

iu ch pha cu phng

TCP Transmission Control Protocol Giao thc iu khin truyn vn

RF Radio Frequency Tn s v tuyn

RIFF Resource Interchange File

Format

nh dng tp tin trao i ti nguyn

SDR Software Defined Radio V tuyn nh ngha bng phn mm

UHD USRP Hardware Driver Trnh iu khin thit b USRP

USRP Universal Software Radio

Peripheral

Phn mm ph v tuyn ngoi vi

WAV Waveform Audio File Format nh dng sng m thanh

.

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Danh mc cc hnh v.

Hnh v M t

Hnh 1.1. S biu din qu trnh giu tin 8

Hnh 1.2. S biu din qu trnh tch tin

Hnh 1.3 Phn loi k thut giu tin.

Hnh 1.4. Quy trnh giu tin trn audio.

Hnh 1.5. Hnh 1.5. Quy trnh tch tin trn audio.

Hnh 2.1 Hnh 2.1 Cu trc h thng SDR.

Hnh 2.2 M hnh cc khi lin kt trong GNU Radio.

Hnh 2.3 Khi GNU Radio.

Hnh 2.4 Khi phn cp trong GNU Radio.

Hnh 2.5 V d trong GRC.

Hnh 2.6 Giao din u tin khi chy chng trnh GNU Radio Companion.

Hnh 2.7 USRP B210.

Hnh 2.8 S khi ca USRP B210.

Hnh 2.9 Kt ni gia my tnh v USRP B210

Hinh 2.10 S h thng ca GNU Radio V USRP B

Hnh 3.1 Giao din chnh ca chng trnh

Hnh 3.2 Chn file nhc

Hnh 3.3 Nhng d liu thnh cng

Hnh 3.4 Quy trnh hi phc d liu

Hnh 3.4 D liu c phc hi thnh cng

Hnh 3.5 Thng bo khi phuc d liu tht bi

Hnh 3.6 M file m thanh.

Hinh 3.7 Ph bin m thanh trc khi nhng d liu

Hnh 3.8 Ph bin m thanh sau khi nhng d liu

Hinh 3.9 Ph bin m thanh trc khi nhng d liu.


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Hnh 3.11 S thit lp kt ni ca my ch.

Hnh 3.12 S thit lp kt ni ca my khch.

Hnh 3.13 M hnh th nghim truyn thng tin b mt qua wifi.

Hnh 3.14 Truyn tp tin New_10_Jan_2015_8_51.wav.

Hnh 3.15 Thu nhn c tp tin wifi.wav

Hnh 3.16 Kt qu tch thng tin b mt t tp tin New_10_Jan_2015_8_51.wav

Hnh 3.17 Kt qu tch thng tin b mt t tp tin wifi.wav

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Li m u.

Ngy nay vi s pht trin ca mng Internet, thng tin tr thnh sn sng trc

tuyn, mi ngi c my tnh u c th kt ni vo Internet thng qua nh cung cp dch

v truy cp Internet v tm kim thng tin mt cch d dng. Cng vi s bng n ca

Internet v cc phng tin multimedia, nhng vn nn nh n cp bn quyn, xuyn tc

thng tin, truy nhp thng tin tri php ... cng gia tng, i hi phi khng ngng tm

cc gii php mi, hu hiu cho an ton v bo mt thng tin.

Gii php bo mt thng tin c s dng ph bin nht l dng cc h mt m.

Vi gii php ny, thng tin ban u (bn r) s c m ha thnh bn mt m (bn

mt) thng mang nhng gi tr v ngha. Chnh iu ny lm cho i phng nghi

ng v tm mi cch thm m. Ngc li, nu chng ta em thng tin nhng vo trong

mt i tng khc, mt file audio t chng hn ta s thu c mt file audio F hu nh

khng sai khc vi F khi nghe bnh thng. Sau F c gi ti ngi nhn. ly li

bn tin t tn hiu F, ngi nhn khng cn i snh vi tn hiu gc. y l tng ca

phng php nhng d liu trn nn tn hiu c nghin cu gn y v c nhiu ng

dng trong giu tin mt, nh giu bn quyn v nhiu ng dng khc....

Vi nhng l do ny ti quyt nh chn t ca n tt nghip l:

Nhng d liu trn nn tn hiu m thanh s dng cng ngh v tuyn nh

ngha bng phn mm.

Mc tiu ca n ny l nghin cu phng php nhng d liu trn nn m

thanh v tm hiu phng php truyn ti tn hiu s dng cng ngh v tuyn nh

ngha bng phn mm SDR. B cc n gm 3 chng:

Chng 1: L thuyt k thut nhng d liu trn nn tn hiu m thanh.

Chng 2: Tm hiu cng ngh v tuyn nh ngha bng phn mm SDR.

Chng 3: Xy dng phn mm nhng d liu trn nn m thanh v m hnh

truyn d liu.

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Chng 4: Kt lun.

Do kinh nhim thc t cn hn ch nn ni dung ca n khng trnh khi nhng

thiu xt. Ti rt mong s gp , ch bo ca cc thy gio v cc bn sn phm ca

n ngy cng hon thin hn.

Ti xin chn thnh cm n!

Ngi thc hin

inh Vn Nam

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Chng1. L Thuyt V K Thut Nhng D Liu Trn Nn

Tn Hiu m Thanh.

1. Tng quan v k thut giu tin (k thut nhng)

1.1. S lc v lch s giu tin.

tng v che giu thng tin c t hng nghn nm v trc nhng k thut

ny c dng ch yu trong qun i v trong cc c quan tnh bo. Mi cho ti vi

thp nin gn y, giu thng tin mi nhn c s quan tm ca cc nh nghin cu v

cc vin cng ngh thng tin vi rt nhiu cng trnh nghin cu. Cuc cch mng s ha

thng tin v s pht trin nhanh chng ca mng truyn thng l nguyn nhn chnh dn

n s thay i ny. Nhng phin bn sao chp hon ho, cc k thut thay th, sa i

tinh vi cng vi s lu thng trn mng ca cc d liu a phng tin sinh ra rt

nhiu nhng vn nhc nhi v nn n cp bn quyn, phn phi bt hp php, xuyn

tc tri php... y l lc cng ngh giu tin c ch v pht trin.

1.2 Khi nim giu tin.

T trc n nay, nhiu phng php bo v thng tin c a ra, trong

gii php dng mt m c ng dng rng ri nht. Thng tin ban u c m ho, sau

s c gii m nh kho ca h m. c nhiu h m phc tp c s dng nh

DES, RSA, NAPSACK..., rt hiu qu v ph bin.

Mt phng php mi khc v ang c nghin cu v ng dng mnh m

nhiu nc trn th gii, l phng php giu tin. Giu thng tin l k thut nhng

mt lng thng tin s no vo trong mt i tng d liu s khc. Mt trong nhng

yu cu c bn ca giu tin l m bo tnh cht n ca thng tin c giu ng thi

khng lm nh hng n cht lng ca d liu gc.

S khc bit ch yu gia m ho thng tin v giu thng tin l m ho lm cho

cc thng tin th hin l c c m ho hay khng, cn vi giu thng tin th ngi ta s

kh bit c l c thng tin giu bn trong

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Knh truyn

Hnh 1.1. S biu din qu trnh giu tin.

Hnh 1.2. S biu din qu trnh tch tin.

Hai s trn hnh 1.1 v 1.2 biu din qu trnh giu tin v qu trnh gii tin.

1.3 Phn loi cc k thut giu tin.

Do k thut giu thng tin s mi c hnh thnh trong thi gian gn y nn xu

hng pht trin cha n nh. Nhiu phng php mi, theo nhiu kha cnh khc nhau

ang v chc chn s c xut, bi vy mt nh ngha chnh xc, mt s nh gi

phn loi r rng cha th c c. S phn loi sau y c Fabien A. P. Petitcolas

xut nm 1999.

B nhng

thng tin

Thng tin

b mt

Phng tin cha c

giu tin

Phng tin

cha( audio,

nh, video..)

Kha

Kha

Phng tin

cha c giu tin

Thng tin

b mt

B gii m

tin

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Hnh 1.3 Phn loi k thut giu tin.

Da trn vic thng k sp xp khong 100 cng trnh cng b trn mt s tp

ch, cng vi thng tin v tn v tm tt ni dung ca khong 200 cng trnh cng b

trn Internet, c th chia lnh vc giu tin ra lm hai hng ln, l thu vn v giu tin

b mt. Nu nh thy vn lin quan n ng dng giu cc mu tin ngn nhng i hi

bn vng ln ca thng tin cn giu (trc cc bin i thng thng ca tp d liu

mi trng) th giu tin b mt li lin quan ti ng dng che giu cc bn tin i hi

b mt v dung lng cng ln cng tt. i vi tng hng ln ny, qu trnh phn loi

theo cc tiu ch khc c th tip tc c thc hin, v d da theo nh hng cc tc

ng t bn ngoi c th chia thu vn thnh hai loi, mt loi bn vng vi cc tc ng

sao chp tri php, loi th hai li cn tnh cht hon ton i lp: d b ph hu trc cc

tc ng ni trn. Cng c th chia thu vn theo c tnh, mt loi cn c che giu

ch c mt s ngi tip xc vi n c th thy c thng tin, loi th hai i lp, cn

c mi ngi nhn thy. Cc thnh tu t c trong lnh vc nghin cu ny bt

u c p dng hiu qu cho mc ch bo v bn quyn, chng sao chp, phn tn tri

php cc sn phm trong mi trng s ho v nhiu mc ch khc. Nhiu phng php

giu thng tin khc nhau c xut, mi phng php c nhng u im, nhc

im ring v thch hp cho mt

Giu thng tin

Giu tin b mt

Nhng thy vn

Thy vn bn vng Thy vn d v

Thy vn hin Thy vn n

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nhm ng dng no .

1.4 Mc ch ca giu tin.

Bo mt thng tin bng giu tin c hai kha cnh. Mt l bo mt cho d liu c

giu, v d giu tin mt: thng tin mt c giu k trong mt i tng khc sao cho

ngi khc khng pht hin c. Hai l bo mt chnh i tng c dng giu d

liu vo. Mt s ng dng ang c trin khai:

- Bo v bn quyn tc gi (copyright protection): y l ng dng c bn nht

ca k thut thu vn. Mt thng tin no mang ngha quyn s hu tc gi (ngi ta

gi n l thu vn - watermark) s c nhng vo trong cc sn phm, thu vn ch

ngi ch s hu hp php cc sn phm c v c dng lm minh chng cho bn

quyn sn phm. Gi s c mt thnh phm d liu dng a phng tin nh nh, m

thanh, video cn c lu thng trn mng. bo v cc sn phm chng li hnh vi

ly cp hoc lm nhi cn phi c mt k thut dn tem bn quyn vo sn phm

ny. Vic dn tem hay chnh l vic nhng thu vn cn phi m bo khng li mt

nh hng ln no n vic cm nhn sn phm. Yu cu k thut i vi ng dng ny

l thu vn phi tn ti bn vng cng vi sn phm, mun b thu vn ny m khng

c php ca ngi ch s hu th ch cn cch l ph hu sn phm.

- Xc thc thng tin v pht hin xuyn tc thng tin (authentication and tamper

detection). Mt tp thng tin s c giu trong phng tin cha, sau c s dng

nhn bit d liu trn phng tin gc c b thay i hay khng. Cc thu vn nn

c n trnh s t m ca i phng, hn na vic lm gi cc thu vn hp l hay

xuyn tc thng tin ngun cng cn xem xt.Trong cc ng dng thc t, ngi ta mong

mun tm c v tr b xuyn tc cng nh phn bit c cc thay i (v d nh phn

bit mt i tng a phng tin cha thng tin giu b thay i, xuyn tc ni dung

hay ch b nn mt d liu).Yu cu chung i vi ng dng ny l kh nng giu thng

tin cao v thu vn khng cn bn vng.

- Du vn tay hay dn nhn (fingerprinting and labeling): Thu vn trong nhng

ng dng ny c s dng nhn din ngi gi hay ngi nhn mt thng tin no

. V d cc vn khc nhau s c nhng vo cc bn copy khc nhau ca thng tin

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gc trc khi chuyn cho nhiu ngi. Vi nhng ng dng ny, yu cu l m bo

an ton cao cho cc thu vn, trnh kh nng xo du vt trong khi phn phi.

- iu khin truy cp (copy control): Cc thit b pht hin thu vn ( y s

dng phng php pht hin thu vn giu m khng cn thng tin gc) c gn sn

vo trong cc h thng c ghi, ty thuc vo vic c thy vn hay khng iu khin

(cho php/cm) truy cp. V d h thng qun l sao chp DVD c ng dng Nht.

- Giu tin b mt (steganography): Cc thng tin giu c trong nhng trng

hp ny cng nhiu cng tt. Vic gii m nhn c thng tin cng khng cn

phng tin cha gc.

1.5 Mi trng giu tin.

K thut giu tin c nghin cu v p dng trong nhiu mi trng d liu

khc nhau nh trong d liu a phng tin (vn bn, hnh nh, m thanh, phim ), trong

sn phm phn mm v gn y l nhng nghin cu trn lnh vc c s d liu quan h.

Trong cc d liu , d liu a phng tin l mi trng chim t l ch yu trong cc

k thut giu tin.

a. Giu tin trong nh (image).

Giu thng tin trong nh, hin nay, l mt b phn chim t l ln nht trong cc

chng trnh ng dng, cc phn mm, h thng giu tin trong a phng tin do lng

thng tin c trao i bng nh l rt ln v hn na giu thng tin trong nh cng ng

vai tr quan trng trong hu ht cc ng dng bo v an ton thng tin nh: xc thc

thng tin, xc nh xuyn tc thng tin, bo v bn quyn tc gi, iu khin truy cp,

giu tin b mt... Do vn ny nhn c s quan tm ln ca cc c nhn, t

chc, trng i hc, v vin nghin cu trn th gii. Thng tin s c giu cng vi

d liu nh nhng cht lng nh t thay i v khng ai bit c ng sau nh mang

nhng thng tin c ngha. Ngy nay, khi nh s c s dng ph bin, giu thng

tin trong nh em li nhiu nhng ng dng quan trng trn nhiu lnh vc trong

i sng x hi. V d i vi cc nc pht trin, ch k tay c s ho v lu tr

s dng nh h s c nhn ca cc dch v ngn hng v ti chnh, n c dng xc

thc trong cc th tn dng ca ngi tiu dng. Phn mm WinWord ca MicroSoft

17

cng cho php ngi dng lu tr ch k trong nh nh phn ri gn vo v tr no

trong file vn bn m bo tnh an ton ca thng tin. Ti liu sau c truyn trc

tip qua my fax hoc lu truyn trn mng. Theo , vic xc thc ch k, xc thc

thng tin tr thnh mt vn quan trng khi vic n cp thng tin hay xuyn tc

thng tin bi cc tin tc ang tr thnh mt vn nn i vi bt k quc gia no, t chc

no. Hn na c nhiu loi thng tin quan trng cn c bo mt nh nhng thng tin

v an ninh, thng tin v bo him hay cc thng tin v ti chnh, cc thng tin ny c

s ho v lu tr trong h thng my tnh hay trn mng. Chng d b ly cp v b thay

i bi cc phn mm chuyn dng. Vic xc thc cng nh pht hin thng tin xuyn

tc tr nn v cng quan trng, cp thit. Mt c im ca giu thng tin trong nh l

thng tin c giu trong nh mt cch v hnh, tng t cch truyn thngtin mt cho

nhau m ngi khc khng th bit c bi sau khi giu thng tin cht lng nh gn

nh khng thay i c bit i vi nh mu hay nh xm. V d v v vic ngy 11-9

gy chn ng nc M v ton th gii, chnh tn trm khng b quc t Osma

BinLaDen dng cch thc giu thng tin trong nh lin lc vi ng bn, v hn

qua mt c cc tnh bo trung ng M CIA v cc c quan an ninh quc t. Chc chn

sau v vic ny, vic nghin cu cc vn lin quan n giu thng tin trong nh s

rt c quan tm.

b. Giu tin trong m thanh (audio).

Giu thng tin trong m thanh mang nhng c im ring khc vi giu thng tin

trong cc i tng a phng tin khc. Mt trong nhng yu cu c bn ca giu tin l

m bo tnh cht n ca thng tin c giu ng thi khng lm nh hng n cht

lng ca d liu gc. m bo yu cu ny, k thut giu thng tin trong nh ph

thuc vo h thng th gic ca con ngi - HVS cn k thut giu thng tin trong m

thanh li ph thuc vo h thng thnh gic - HAS. Mt vn kh khn l h thng

thnh gic ca con ngi nghe c cc tn hiu cc di tn rng v cng sut ln nn

gy kh khn i vi cc phng php giu tin trong m thanh. Nhng h thng thnh

gic ca con ngi li km trong vic pht hin s khc bit cc di tn v cng sut,

iu ny c ngha l cc m thanh to, cao tn c th che giu c cc m thanh nh thp

18

mt cch d dng. Cc m hnh phn tch tm l ch ra im yu trn v thng tin ny

s gip ch cho vic chn cc m thanh thch hp cho vic giu tin. Vn kh khn th

hai i vi giu thng tin trong m thanh l knh truyn tin. Knh truyn hay bng thng

chm s nh hng n cht lng thng tin sau khi giu. V d nhng mt on java

applet vo mt on m thanh (16 bit, 44.100 Hz) c chiu di bnh thng th cc

phng php ni chung cng cn t nht l 20 bit/s. Giu thng tin trong m thanh i hi

yu cu cao v tnh ng b v tnh an ton ca thng tin. Cc phng php giu thng

tin trong m thanh u li dng im yu trong h thng thnh gic ca con ngi.

c. Giu tin trong phim (video) .

Cng ging nh giu thng tin trong nh hay trong m thanh, giu tin trong phim

cng c quan tm v c pht trin mnh m cho nhiu ng dng nh iu khin truy

cp thng tin, xc thc thng tin v bo v bn quyn tc gi. V d cc h thng chng

trnh tr tin xem theo on vi cc on phim (pay per view application). Cc k thut

giu tin trong phim cng c pht trin mnh m v cng theo hai khuynh hng l

thu vn s v giu thng tin. Nhng phn ny ch quan tm ti cc k thut giu tin

trong phim. Mt phng php giu tin trong phim c Cox a ra l phng php phn

b u. tng c bn ca phng php l phn phi thng tin giu dn tri theo tn s

ca d liu gc. Nhiu nh nghin cu dng nhng hm cosin ring v cc h s

truyn sng ring giu tin. Trong cc thut ton u tin thng cc k thut cho php

giu cc nh vo trong phim nhng thi gian gn y cc k thut cho php giu c m

thanh v hnh nh vo phim. V d Swanson s dng phng php giu theo khi,

phng php ny giu c hai bt vo khi 8*8. Hay gn y nht l phng php

ca Mukherjee l k thut giu m thanh vo phim s dng cu trc li a chiu...

Giu tin l mt cng ngh mi phc tp, ang c cc nh khoa hc tp trung nghin

cu nhiu nc trn th gii nh c, M, , Canada, Nht Bn...Tuy nhin, nhng kt

qu thc nghim cho thy c th ng dng thc t th lnh vc ny cn phi c thm

thi gian nghin cu thm nh nhng cc nh khoa hc cng khng nh rng y l

mt cng ngh mi y ha hn cho vn an ton v bo mt thng tin. Cng vic hin

19

nay ca cc nh khoa hc l ang tp trung xy dng mt h thng l thuyt chnh xc

cho vn giu tin, y l mt mnh t mi cho cc nh khoa hc khm ph.

2. Tp tin m thanh( file wav).

2.1 nh ngha File .Wav.

Wave File l tp tin cha cc d liu ca mu m thanh c s ha. Phng php

s ha m thanh hin nay l phng php PCM. Phng php ny s ly mu m thanh

vi tn s khong 11.025 kHz cho n 44.1 kHz. Mi ln ly mu, s liu ny li c

lng t ha bng mt hay hai byte cho mt mu m thanh. Nh vy tn s ly mu cng

cao, s byte dng lng t ha cng nhiu th m thanh pht li cng trung thc, nhng

li tng s byte cn lu tr.

2.2 Cu trc File .Wav.

Mt file wave l mt phn ca mt lp file ln hn dng bi cc hm Multimedia

ca Windows l cc file RIFF (Resource Interchange File Format). Mt file RIFF bao

gm mt hoc nhiu chunk. Mi chunk c con tr ch n chunk k tip. Mi chunk c

mt m t kiu theo sau bi mt s d liu. Mt ng dng c cc file RIFF c th i

qua mt s chunk, c cc chunk cn quan tm v b qua cc chunk khng lin quan.

Ly mu.

Ta bit, sng m l mt lot cc dao ng ca vt cht trong mi trng truyn m.

Vo mi mt thi im nht nh, vt cht c mt bin nht nh. Tng tng nh

trong dao ng ca con lc ng h. Mi lc con lc c mt lch no so vi v tr

cn bng chnh gia. Khi mun a m thanh vo m ha trn my tnh, th ta cn phi

xc nh bin dao ng ca sng m vo cc thi im khc nhau. Vic gi l ly

mu. Trong mt giy pht ra m thanh, ngi ta ly mt s mu bin m a vo d

liu. Con s y gi l tn s ly mu (Sample rate). Th d, ta m phn thuc tnh ca

mt tp tin m thanh v thy Sample rate = 44.1 kHz (44100 Hz) ngha l trong mt

giy ly mu 44100 ln. Mt iu d nhn thy l tn s ly mu cng cao th m thanh

c m ha cng chnh xc.

20

Hnh 1.3 Ly mu.

Hnh trn y minh ha vic trch mu. ng mu xanh l th sng m. Mi

khung (lt ct) mu xm l mt mu m thanh. Cc chm l cc gi tr (bin dao

ng) s c ly.

Chiu su bit.

Mt yu t khc cng tc ng ti chnh xc ca vic ly mu m thanh. l

chiu su bit, trn bng thuc tnh tp tin WAV ghi l Audio sample size , thng l 8

hoc 16 bits. Ta bit, 8 bits l 1 byte , lu c 256 gi tr (t 0 ti 255). Cn 16 bits l

2 bytes tc 1 word, lu c 65536 gi tr (t -32768 ti 32767). S bit cng ln th m

thanh ly mu cng chnh xc. Ging nh thang im 100 s chm ng (chi tit) hn

thang im 10 vy.

Knh m thanh (Channels ).

m thanh chia ra 2 knh tri-phi l Stereo . Cng c m thanh ch mt knh (cng

mt lung d liu i ra hai loa) l Mono. i vi m thanh hai knh, cc mu (sample )

cng phn ra hai knh.

Kch thc mu trch.

Cng thc kch thc mu trch (tnh bng byte ) l:

LengthOfSample = Channels * AudioSampleSize / 8.

Tm tt cu trc ca wave file nh sau:

RIFF chunk.

21

V tr Kch thc

(byte)

Tn trng

00-03 4 Chui "RIFF".

04 - 07 4 Kch thc tp tin - 8.

08 - 11 4 Chui "WAVE".

FORMAT chunk.

V tr Kch thc

(byte)

Tn trng

12 - 15 4 Chui "fmt " (k t cui l du khong trng, m ASCII 32).

16-19 4 Kch thc FORMAT chunk, mc nhin l 16.

20 - 21 2 nh dng m ha m thanh, thng l 1 (PCM).

22 - 23 2 S knh, 1 (Mono) hay 2 (Stereo).

24 - 27 4 Tn s ly mu, tnh bng Hz (mu/giy).

28 - 31 4 S byte d liu mi giy.

BytesPerSecond=SampleRate*Channels *

AudioSampleSize / 8

32 - 33 2 S byte trong mt mu ly.

BytesPerSample = Channels * AudioSampleSize / 8 .

34 - 35 2 Chiu su bit (AudioSampleSize), l 8 hoc 16.

DATA chuck.

V tr Kch thc

(byte)

Tn trng

36 - 39 4 Chui "data".

40 - 43 4 Kch thc d liu m thanh.

DataSize = Samples * Channels * AudioSampleSize / 8.

Samples l tng s mu trch (ThiLng_Giy *

TnSTrchMu).

22

44 - cho

ti ht

D liu m thanh.

3. K thut giu tin trong m thanh (audio).

3.1 M hnh k thut giu tin trong m thanh.

K thut giu tin trong audio bao gm hai qu trnh l:

Qu trnh 1: Giu tin vo audio.

Hnh 1.4. Quy trnh giu tin trn audio.

u vo:

Thng tin b mt: Ty theo mc ch ca ngi s dng m thng

tin b mt y c th l thng ip, hnh nh, video, m thanh

Audio gc: l audio( tp tin nhc nh dng .wav) c chn lm mi

trng giu tin.

u ra:

Audio c giu tin.

Qu trnh 2: Tch tin t audio c giu tin.

Thut ton

giu tin

Thng tin

b mt

Audio c

giu tin.

Audio gc

Kha bo

mt

23

Hnh 1.5. Quy trnh tch tin trn audio.

u vo:

Audio giu tin.

Kha bo mt.

u ra:

Thng tin c che giu.

3.2. Mt s k thut giu tin trong audio.

3.2.1. M ha LSB (Least Significant Bit).

Phng php m ha LSB l cch n gin nht nhng d liu vo trong audio.

Phng php ny s thay th bt t quan trng nht (thng l bt cui) ca mi mu d

liu bng bt thng tin giu. V d mu 8 bt nh sau:

1 1 0 1 0 0 1 0

Sau khi giu bt 1s nh sau:

1 1 0 1 0 0 1 1

Hnh 1. Minh ha k thut giu LSB

u im ca phng php ny l d thc hin v cho php giu d liu nhiu. C

th tng thm d liu giu bng cch dng hai bt LSB. Tuy nhin cch ny lm cng lm

tng nhiu trn i tng cha dn n i phng d pht hin v thc hin cc tn

cng. V vy d liu cha cn phi c chn trc khi giu s dng phng php m

Kha bo

mt

Audio

c giu tin Thng tin

b mt

Thut ton

tch tin

24

ha LSB. tng an ton cho k thut ny, ta s dng b sinh s nguyn ngu nhin

sinh ra cc v tr cc mu c chn giu ch khng phi cc mu lin tc. B sinh s

ny s dng mt kha b mt key nh l phn t khi to ca b sinh s. Kha key ny

c s dng trong c qu trnh giu tin v gii tin. Lu l b sinh s khng to ra cc

gi tr trng nhau trnh trng hp mt v tr c giu hai ln.

3.2.2. M ha Parity (Parity Coding).

Thay v chia d liu thnh cc mu ring l, phng php m ha chn l chia d

liu thnh cc nhm mu v giu tng bit thng tin vo trong cc nhm mu ny. Nu

parity bt ca nhm mu ny khng trng vi bit thng tin giu th ta tin hnh iu chnh

mt bt no trong nhm mu ny. Phng php ny cho ta nhiu s la chn hn khi

thay i 1 bt v c v kn o hn so vi phng php iu chnh LSB. C hai phng

php LSB v Parity u c nhng hn ch. Do tai ngi kh nhy nn nhng thay i

trn d liu cha s sinh nhiu v ngi nghe rt d nhn ra. Mt im na l hai phng

php ny khng bn vng v thng tin s b mt sau khi thc hin vic ly mu li. Mt

trong nhng cch khc phc l thc hin vic giu nhiu ln. Tuy nhin cch ny cng c

hn ch l n lm tng thi gian x l.

3.2.3 M ha Phase (Phase Coding).

Phng php m ha pha gii quyt c cc hn ch do sinh ra nhiu ca hai

phng php giu d liu trn. Phng php m ha pha da vo tnh cht l cc thnh

phn ca pha khng gy nh hng n h thng thnh gic ca con ngi nh nhiu.

Vic giu tin c thc hin bng cch iu chnh pha trong ph pha ca d liu s.

D liu gc. D liu sau khi giu.

Hnh 1.7 K thut m ha pha.

25

Qu trnh m ha pha c chia thnh cc bc sau:

a. D liu m thanh gc c chia thnh cc segment nh hn c chiu di bng

chiu di vi d liu cn nhng.

b. Thc hin bin i Fourier ri rc DFT trn mi on

c. Tnh lch pha gia cc on k nhau.

d. Gi tr chnh xc cc pha ca cc on c th thay i nhng mi lin h v s

khc nhau v pha gia cc segment lin tip phi c m bo, v vy thng tin giu ch

c php giu trong vector pha ca on u tin. Vic iu chnh pha ca on u

c p dng da trn cng thc:

Phase_new=/2 nu message=0

Phase_new=-/2 nu message=1

e. Ghp cc segment li v tin hnh DFT

Ngc to li d liu m thanh. nhn c tin giu bng k thut ny, ngi

nhn phi bit di ca segment, sau thc hin DFT nhn tin. Mt yu im ca

phng php ny l t l d liu thp do thng tin ch c giu vo segment u tin. C

th ci thin bng cch tng di segment. Tuy nhin cch ny s lm cho tin giu d

pht hin. Phng php m ha pha ch thch hp cho vic giu lng nh thng tin.

3.2.4. K thut tri ph.

Thng thng cc file audio c truyn qua cc knh truyn thng, cc knh

truyn thng ny s tp trung d liu audio trong vng hp ca ph tn s duy tr nng

lng v tit kim bng thng. Cc k thut tri ph c gng tri thng tin b mt vo

trong ph tn s ca d liu audio cng nhiu cng tt. N cng tng t nh k thut

LSB l tri ngu nhin thng tin giu trn ton b tp tin audio. Li im ca phng

php tri ph l n bn vng trc mt s tn cng. Tuy nhin n cng c hn ch l sinh

nhiu v d nhn ra. Hai phng php tri ph s dng trong giu tin audio l DSSS

(Direct Sequency Spread Spectrum) v FHSS (Frenquency Hopped Spread Spectrum).

3.2.5 K thut m ha echo.

26

Bng cch dng thi gian tr khc nhau gia tn hiu gc v ting vang th hin

tng ng gi tr nh phn 1 hoc 0, theo cch d liu c giu vo tp tin audio.

giu nhiu hn mt bit, tn hiu gc c chia thnh cc on ngn hn v mi on sau

c th c to ting vang giu s bit mong mun. D liu cha cui cng bao

gm cc on c m c lp ni li theo th t chia ban u. K thut giu tin da vo

ting vang rt hiu qu trong cc tp tin audio cht lng cao. Cc tp tin m thanh cha

lm gim cht lng v khng c qu nhiu on yn lng thng dng k thut ny

giu tin. Mt cch tip cn khc l tin hnh m ha chui bit theo mt cch no gip

ta pht hin ra li.

3.3 Cc tn cng trn cc h giu tin trong m thanh.

D liu sau khi c nhng tin c th chu mt s tn cng. Cc kiu tn cng ny

c th lm sai lch mt phn hoc ton b tin giu. Sau y l mt s loi tn cng:

Ly li mu: Kiu tn cng ny lm thay i cu trc file gc. Mt mu d liu

trong file mi c th nhiu hoc t hn s bt so vi file gc.

Lc thng: Phng php ny ch chn li tn s d liu tha mn trong iu kin

no . Cc phng php du tin trn min tn s s b nh hng nu chu tc

ng ca loi tn cng ny.

Cng nhiu: Loi tn cng ny c thc hin bng cch cng thm tn hiu nhiu

vo trong tn hiu cha, dn n khi gii tin ngi nhn s nhn sai so vi tin giu.

Bin i A/D, D/A: Tn cng theo kiu ny c thc hin bng cch bin i tn

hiu sau khi nhng t dng s sang tng t sau thc hin bin i li t tng

t sang s khin cho tn hiu nhn c sai khc so vi tn hiu khi truyn. Dn

n vic bn tin mt nhn c sai khc so vi bn tin trc khi nhng.

Tt c cc kiu tn cng trn u lm cho tin giu nhn c s sai khc so vi tin khi

nhng.

3.4 Yu cu k thut giu tin trong m thanh( audio).

Khi giu thng tin trong audio, thng tin s c giu cng vi d liu

audio nhng cht lng audio t thay i v gn nh khi nghe bnh thng chng ta

27

khng th pht hin ra rng ng sau audio l khi thng tin c n trong . V mt

c im ca giu thng tin trong audio l thng tin c giu mt cch v hnh, n

l mt cch truyn thng tin mt cho nhau m ngi khc khng th bit c bi sau khi

giu thng tin th cht lng m thanh gn nh khng thay i.

K thut giu tin trong audio thng ch nhng yu cu c bn sau y:

Vic tin c giu trong audio khng lm nh hng ti cht lng ca audio

chn tin.

Cho php cc tin c giu c th tn ti c qua cc php bin i audio hay

cc hnh thc tn cng c khc.

Ch c bn nhn c cp mt kha v bng cc k thut tch ph hp mi c th

ly c tin trong audio.

4. Tm tt chng.

Chng 1 cung cp cho ngi c kin thc tng quan v k thut giu tin, mc

ch giu tin, v mi trng u tin. Ngoi ra cn cung cp khi nim v cu trc v

tp tin wav, cc k thut, yu cu giu tin trong m thanh v nhng kiu tn cng trn

cc h thng giu tin trong m thanh.

28

Chng 2. Cng Ngh V Tuyn nh Ngha Bng Phn Mm

1. Gii thiu cng ngh v tuyn nh ngha bng phn mm SDR.

Ngy nay Cng ngh v tuyn nh ngha bng phn mm SDR tr nn ph

bin trong vic hnh thnh mng khng dy. tng ng sau vic thnh lp h thng

SDR l gii quyt cc vn ca phn cng trn phn mm. Trong cc h thng SDR,

hu ht cc tn hiu c x l thng qua lp trnh bng cch s dng Field-

Programmable Gate Arrays (FPGA), General Purpose Processors (GPP) hoc bt k thit

b c th lp trnh khc. Cc c trng c bn ca SDR l xc nh cc dng sng truyn

i v b gii iu ch cc dng sng nhn c. c im ny ca SDR cung cp linh

hot cho vic nghin cu v pht trin truyn thng khng dy. Mt lot cc phng

php mi, thut ton , giao thc c th c thc hin v kim tra d dng tng t nh

vic thc hin th nghim trn nn tng h thng thng tin v tuyn. t c iu

ny, tt c cc thnh phn tn s v tuyn RF nh : b trn v cc b lc cng c

chuyn n cc cc phn mm, ti y vic x l tn hiu k thut s c lm vic trn

bng tn c s. Vi vic chi ph thc hin thp, tc chuyn i cao t tn hiu s sang

tng t v ngc li khin cho h thng SDR c s dng trong nhiu hn thc t.

Cu trc h thng SDR c th hin hnh sau:

Hnh 2.1 Cu trc h thng SDR

29

H thng SDR trnh by trn l trong trng hp l tng nn rt n gin v

linh hot. Tuy nhin, trong thc t n khng n gin nh vy do cc thit b phn cng

cn nhiu hn ch. C th nh sau:

Chuyn i tng t sang s: Theo nh l ly mu Nyquist th t l ly

mu phi cao gp i bng thng nhng b chuyn i ADC hin nay c

kh nng tc ly mu l 100 Msps. Do , gii hn bng thng 50 MHz.

Trong khi bng thng ny cho hu ht cc ng dng hin ti c tn s sng

mang l thng cao hn 50 MHz. V vy, to ra tn s RF cui cng

ngi ta yu cu chuyn i cc tn hiu nhn c sang mt tn s trung

gian (IF) .

Tc bus: Mt vn c a ra l vic truyn d liu t b chuyn

i ADC sang mytnh. Trong thc t, tc bus ti a i vi cc d liu

c th t l hn ch ca t l mu v phn gii ca cc mu. Tc bus

trong my tnh thng dao ng t mt vi Mbps n vi Gbps.

tr: Ni chung my tnh c nhn khng c xy dng x l cc ng

dng theo thi gian thc. V vy, trong thc t mt tn ti mt tr

kh cao trong h thng SDR. Nhiu tiu chun khng dy i hi thi gian

chnh xc. Do , tr cn c xem xt k lng trong qu trnh trin

khai thc hin trong h thng SDR.

Tuy nhin, nhiu gii php c xut gii quyt nhng vn trn gip SDR

tr thnh mt phng php tip cn vi chi ph thp. C rt nhiu m hnh SDR c th

nghim. Hu ht trong n bao gm cc phn mm min ph v phn cng c dng

truyn RF. Hin nay, phn mm GNU Radio v SDR4All Tool l phn mm min ph

xy dng SDR.

2. Cc ng dng ca h thng SDR.

30

Thng tin trong qun s: cc u im ca h thng SDR l tnh an ton ca thng

tin, m ho bo mt, s dng linh hot, tch hp nhiu chc nng v ch cng tc, kh

nng kt ni vi my tnh v cc mng thng tin lin lc khc theo cc tiu chun quc

t. SDR cn cho php t chc mng thng tin ln cho c h thng, trong bao gm

nhiu loi thit b cho cc qun binh chng vi s a dng cc tiu chun v dng loi

ch thng tin khc nhau.

Mt u th ca cng ngh SDR trong thng tin qun s l khi cc chc nng ca

thit b c thc hin bng cc thut ton tng ng v c lp trnh, np vo trong

thit b. Kch thc ca thit b khi nh i rt nhiu, vi cc thit b cm tay cng c

y chc nng c bn. n gin, gn nh cho ngi lnh nhng vn m bo chc

nng lin lc khng ch vi ng i, cc n v chin thut khc m cn c kh nng

lin lc vi cc n v, qun binh chng khc do c th hot ng vi bng tn rt rng,

bao gm nhiu dng sng khc nhau.

Thng tin v tuyn dn s: c th xt cho cc h thng thng tin di ng mt t. Do

s cnh tranh ca cc nh sn xut thit b, cc nh cung cp dch v di ng. Bt c mt

h thng hay mt dch v no c chp nhn phi th hin c u im trong tnh

nng ca n ph hp vi mt mc gi c hp l. Khi mun thay th cc h thng c hoc

mun nng cp thm cc dch v, p dng cc tiu chun mi m thay i ton b phn

cng th s rt tn km v lng ph. Khi s mang li hiu qu thng mi cao hn cho

cc nh sn xut v cung cp dch v v cng mang li li ch kinh t cho ngi s dng

do h thng c thi gian s dng lu hn vi mt s lng dch v khai thc tng ln,

vi s yu cu cao hn ca ngi s dng. ng thi, SDR cn cho php a vo s

dng cc ng truyn ring, cc knh truyn thu ring an ton cho cc cng ty. Vic

tch hp nhiu dch v trn mt thit b em li li ch khng ch cho cc nh sn xut,

kinh doanh m cn em li s tin li ln cho ngi s dng. Bng vic ch to ra cc

thit b truyn thng a phng tin lm cho ngi dng ch cn mang mt thit b m

31

vn c th dng nhiu chc nng khc nhau: in thoi, my tnh b ti cho cc ng dng

s liu, cc yu cu tc khc nhau: th in t, trnh duyt web, th thoi

Vic a thm ng dng c cng ngh mi vo khai thc trn di tn s dng

mang li hiu qu bng tn. Tn s v tuyn l mt ti nguyn m nhiu nh cung cp

dch v mun s dng kinh doanh. Do s dng di tn mt cch hiu qu l mt

yu cu quan trng. Nh vic a vo trin khai h thng thng tin di ng c bit SMR

(Specialised Mobile Radio) M trn h thng d liu ca chu u mang li nhng

hiu qu tch cc to ln. Ngoi ra SDR cn cho thy cc ng dng quan trng khc ca

n trong thng tin v tinh, thng tin dn ng, hng hi v lnh vc an ninh cng cng,

cc h thng c s d liu...

ng dng SDR trong lnh vc hng khng c th hot ng theo nhiu tiu chun v

giao din v tuyn, to iu kin thun li cho s dng, nng cp khi cn thay i, cung

cp nhiu dch v cng tc. u im khc l thit b v tuyn cu hnh mm l mt

kiu kin trc m cho php nhiu nh cung cp, sn xut cng tham gia, gim bt thi

gian pht trin sn phm.

3. GNU Radio.

GNU Radio l phn mm m ngun m c xy dng nhm h tr vic thc

hin h thng SDR (software-defined radio) trn cc phn cng thng dng. Chng ta

hon ton c th s dng v khai thc phn mm GNU Radio mt cch min ph. Mc

ch ca GNU Radio theo nh sng lp Eric Blossom l: Gii quyt cc vn phn

cng trn phn mm .GNU Radio xy dng cc khi khc nhau x l tn hiu. Cc

khi chc nng ca GNU Radio bao gm:

Thc hin cc php ton: cng, tr, nhn, chia, logarit v logic.

Thc hin cc khi FFT, IFFT.

Thc hin cc b lc thng cao, thng thp, thng di, chn di, b

FFT, FIR, IIR.

32

Thc hin cc b iu ch v b gii iu ch nh: FM, AM, PSK,

QAM, OFDM.

Thc hin cc khi iu khin: Automatic Gain Control (AGC),

Detect Peak, Thresold.

Thc hin cc kiu chuyn i: Float sang short Block, Int sang

Fload Block v Complex sang Real.

Phn mm GNU Radio h tr cc ngun v ch n ca tn hiu nh sau:

Ngun c nh ( constant source )

Ngun nhiu (noise Source).

Ngun ngu nhin ( random source).

Ngun vector ngu nhin (vector Source).

Ngun v ch USRP (USRP Source, sink Source)

Ngun thng bo (message sources).

OScillascope sink, Biu dng mt, FFT sink, Waterfall sink v

Histogram sink.

Ngun v ch audio ( audio Source, audio Sink).

Ngun v ch File (File Source, File Sink).

Ngun v ch TCP(TCP Source, TCP Sink)

Ngun v ch UDP( UDP Source, UDP Sink).

Ban u GNU Radio chy trn h iu hnh LINUX . Hin nay n h tr cc h iu

hnh khc nh: UNIX, Windows v MAC.

3.1 Cu trc GNU Radio.

Cu trc GNU Radio gm hai thnh phn. Th nht l cc khi thc hin x l tn

hiu s bng ngn ng C++ lm nhng cng vic nh: lc, I/O, FFT/IFT, m ha, gii

m v b iu ch/ b gii iu ch. Th hai l vic dng Python scripts kim sot d

liu ca cc khi. Vic s dng Python scripts cho php d dng cu hnh v thao tc

cc chc nng , thng s khc nhau ca h thng. N tng t nh vic lin kt cc khi

vt l RF xy dng phn cng ca thng tin v tuyn, ngi dng c th xy dng h

33

thng SDR bng cch ni cc khi c xy dng trn phn mm GNU Radio vi USRP

l s kt hp phn cng RF vi phn mm GNU Radio. Nhim v chnh ca USRP l

thc hin cc hot ng tnh ton nh lc, chuyn i ln v chuyn i xung. Cc

USRP, USRP2 v phin bn hin ti USRP N c kt ni vi mt my tnh thng qua

mt cng USB 2.0 hoc mt cp Ethernet tng ng v ng dng lp trnh giao din

(API) trn nn tng phn mm GNU Radio iu khin cc thit b USRP.

Hnh 2.2 M hnh lin kt cc khi trong GNU Radio.

Nhn chung, khi GNU Radio th hin trong hnh 2.2 d liu c thc hin lin

tc theo mt lung nht nh. Mi khi bao gm mt tp hp cc cng u vo hoc u

ra c th c c u vo v u ra. N nhn c d liu t cng u vo v x l d liu

cho cng ra ca n. Khi c bit c l khi ngun v ch ch c mt cng vo hoc

cng ra. Mi khi xc nh s lng ti thiu v ti a ca u vo v u ra c th c,

cng nh cc kiu d liu trn cng tng ng. Cc kiu d liu h tr:

c - complex interleaved floats (8 Bytes each).

f - floats (4 Bytes).

s - short integers (2 Bytes).

b - Byte integers (1 Bytes).

Mi khi nh ngha mt hm chc nng general_work() thc hin trn u vo

cho kt qu d liu u ra. Khi cng cung cp mt hm chc nng forecast() tr v h

thng s lng lung d liu u vo n i hi phi thc hin v s lng lung d liu

u ra n to ra lm u vo cho cc khi khc.

Block

E

Block

C

Block

G

Block

F

Block

K

Block

H

Block

D

Block

B

Block

A

Block

L

34

Hnh 2.3 Khi GNU Radio

Tc lung d liu ca cc u vo khc nhau ca khi c th khc nhau nhng

lung d liu u ra phi ging nhau. C u vo v u ra ca mt khi c b m lin

quan. Mi lung d liu u vo / u ra c mt b m c / ghi. Khi c d liu x l

tn hiu t b m c. Sau khi x l, khi s ghi lung d liu thch hp vo b m

ghi. Tt c d liu trong b m c s dng thc hin cc cnh trong flowgraph:

cc b m ghi mt khi l b m c ca khi truc trong flowgraph. B m trong

GNU Radio c ghi mt ln v c nhiu ln theo c ch b m First in First out. N

c th hiu l l mt lung d liu u ra c th kt ni vi mt hoc nhiu lung d liu

u vo (s) v mt u vo nhn d liu t ch c mt u ra. Khi trong Python c

kt ni bi cc chc nng kt ni o n ch ra cch cc lung d liu u ra (s) ca mt

khi kt ni vi cc lung d liu u vo ca mt hoc nhiu hn cc khi ngun. C

ch ca flowgraph cho php t ng xy dng cc flowgraph v c n vi ngi s

dng. Chc nng chnh ca c ch flowgraph l vic phn phi ca b m lung d liu

kt ni cc khi.. Sau khi b m c cp pht ,n c lin kt vi cc lung d

liu u vo v u ra ca cc khi thch hp.

Mt khi phn cp c th c to ra bng cch kt hp mt s khi nh trong

Hnh 2.3. Mt khi phn cp c xy dng bng Python cng vi khi khc chng c

th c kt hp thnh mt khi phn cp mi.

GNU Radio

Block

GNU Radio

Block

C++ Class

35

Hnh 2.4 Khi phn cp trong GNU Radio.

Trong qu trnh xy dng s trn GNU Radio chng ta cn kim tra u vo ca

tng khi v hm forecast () c s dng quyt nh tc lung d liu nhn c

t u vo. Nu d liu l ph hp vi cc b m u vo. Khi s thc hin hm chc

nng general_work(). Nu d liu khng ph hp vi b m u vo ca khi n s

c vo khi tip theo trong flowgraph. B qua khi s khng c thc hin cho n

khi c d liu u vo ph hp. Cc lung d liu c chy 35ien tc theo s c

xy dng trn GNU Radio.

3.2 GNU Radio Companion.

GNU Radio Companion (GRC) l mt giao din ha cho ngi s dng GNU

Radio. GNU Radio l mt cng c m ngun m da trn Python / C ++ xy dng

SDR. GRC cho php kt ni cc thnh phn v to ra mt s lung tn hiu bng cch

s dng cng c ko, th cc khi. Cc hnh phn trong khi c thc hin bi C ++ v

kt ni bng cch s dng ngn ng lp trnh Python. GRC l mt phn ca GNU Radio

v c pht trin bi Josh Blum . Mc d, lp trnh trn GRC khng linh hot nh lp

trnh Python nhng n trc quan hn vi ngi s dng.

V d trong GNU Radio Companion.

GNU Radio

Block

GNU Radio

Block

GNU Radio

Block

36

Hnh 2.5 V d trong GRC.

3.3 Ci t phn mm GNU Radio.

u tin my tnh phi c ci Ubuntu 14.04 LTS.

Bc 1: M Terminal (Ctrl+Shift+T).

Bc 2: S dng cc dng lnh sau.

$ wget http://www.sbrac.org/files/build-gnuradio

$ chmod a+x ./build-gnuradio

$ ./build-gnuradio

Vic ci t GnuRadio s hon thnh sau mt khong thi gian.

chy chng trnh vo Terminal v g dng lnh gnuradio-companion.

Giao din u tin ca chng trnh :

37

Hnh 2.6 Giao din u tin khi chy chng trnh GNU Radio Companion.

4. Gii thiu USRP B210.

USRP l phn cng ph bin nht c s dng vi phn mm GNU Radio xy

dng h thng SDR. USRP l mt dng cc thit b phn cng c pht trin bi Matt

Ettus.

Hnh 2.7 USRP B210.

38

4.1 Mt s tnh nng ca USRP B210.

Di tn RF ph sng t 70 MHz n 6 GHz.

H tr 2 angten thu( 2RX) v 2 angten pht(TX).

Giao tip vi my tnh bng USB 3.0.

FPGA loi Xilinx Spartan 6 XC6SLX150.

Bng thng truyn ln trong trng hp 1 knh truyn v 1 knh nhn l 56 MHz.

Bng thng truyn ln trong trng hp 2 knh truyn v 2 knh nhn l 30.72 MHz.

Ngun cung cp l ngun mt chiu.

C kh nng cung cp GIPO.

Cho php th nghim vi cc tn hiu:

FM.

TV broadcast.

Cellular.

Wifi.

4.2 Cc thng s k thut USRP B210.

Bng 1 Mt s thng s k thut ca USRP B210:

Thng s k thut. Gi tr n v

Ngun

Ngun DC 6 V

Thng s B chuyn i v xung clock.

Tc ly mu ADC(ln nht) 61.44 MS/s

phn gii b ADC 12 bit

ADC Wideband SFDR 78 dBc

Tc ly mu DAC(ln nht) 61.44 MS/s

39

phn gii b DAC 12 bits

Tc ly mu ca tn hiu 61.44 61.44

chnh xc tn s 2.0 ppm

W/ GPS Unlocked TCXO Reference 75 ppb

W/ GPS Locked TCXO Reference < 1 ppb

Thng s ca RF( 1 knh)

SSB/LO Suppression -35/50 dBc

3.5 GHz 1.0 deg RMS

6 GHz 1.5 deg RMS

Nng lng u ra >10 dBm

IIP3 (@ typ NF) -20 dBm

Nhiu thu

40

Hnh 2.8. S khi ca USRP B210.

4.5 Kim tra USRP B210 trn nn LINUX.

Bc 1: M 2 Terminals

Bc 2: Cm cap USB 3.0.

Bc 3: Chy dng lnh.

$ cp /etc/rsyslog.d/50-default.conf ~/Desktop/$ cd ~/Desktop$ mv 50-default.conf 50-

default_backup.conf$ gedit 50-default_backup.conf

N s m ra tp tin 50-default.conf to edit

##*.=info;*.=notice;*.=warn;

\# auth,authpriv.none;\# cron,daemon.none;

\# mail,news.none -/var/log/messages

#Remove all # .

Lu v ng tp tin.

Chy lnh:

$ sudo mv -f ~/Desktop/50-default.conf /etc/rsyslog.d/50-default.conf

$ sudo restart rsyslog

Bc 4: Kim tra USRP driver.

$ tail -f /var/log/messages

Download file uhd_fft.py by link:

http://gnuradio.org/redmine/projects/gnuradio/repository/revisions/a69f26230680fa177c5

3cf75a3a5c6f469b8afb3/entry/gr-uhd/apps/uhd_fft.py

Sao chp tp tin n Home folder .

Kt ni thit b USRP vi my tnh.

M Terminal v chy lnh kim tra thit b USRP: $ python ~/uhd_fft.py

4.6 Kt ni gia USRP B210 v GNU Radio.

41

Hnh 2.9 Kt ni gia my tnh v USRP B210

Hinh 2.10 S h thng ca GNU Radio V USRP B210.

Hnh 2.10 Giao tip d liu gia phn mm GNU Radio v USRP B210.

GNU Radio ci t UHD (USRP Hardware Driver):

Khi UHD source: Cung cp dng d liu RX ti cc khi x l tn hiu trong

phn mm GNU Radio.

Khi UHD sink: Cung cp dng d liu TX t cc khi x l

42

5. Tm tt chng.

Qua chng ny rt ra c kin thc tng qut v cng ngh v tuyn nh ngha

bng phn mm SDR, phn mm GNU Radio, USRP v cch kt ni gia phn mm

GNU Radio v USRP. T m ra hng nghin cu mi cng ngh truyn thng khng

dy v xy dng h thng truyn dn d liu trong chng tip theo.

43

Chng 3 Xy Dng Chng Trnh Nhng D Liu Trn Nn

Tn Hiu m Thanh

Trong n ny d dng cho vic thc hin nhng d liu trn nn tn hiu m

thanh em chn d liu cn nhng l tp tin nh dng text, tn hiu m thanh l tp tin

nh dng .wav v s dng k thut m ha LSB.

1. K Thut M Ha LSB.

K thut m ha LSB l cch n gin nht che giu thng tin trong mt i

tng m thanh k thut s. M ha LSB cho php mt s lng ln cc d liu c

giu bng cch thay th cc bit t quan trng nht (LSB) ca mi im ly mu bng mt

bt mt thng tin nh phn Hnh 3.1 minh ha cch cc thng tin b mt c m ha

trong mt mu 8-bit s dng k thut LSB. Tc truyn d liu trong m ha LSB l 1

kbps mi kHz. Trong mt s m ha LSB, hai bt LSB ca mt mu c thay th bng

hai bit thng tin b mt. N lm tng s lng d liu c th c m ha nhng n cng

lm tng nhiu trong cc tp tin m thanh. trch xut mt thng tin b mt t mt tp

tin m thanh c m ha LSB (i tng stego), ngi nhn yu cu truy cp trnh t

ca mu c s dng trong qu trnh nhng. Thng thng, di ca cc thng tin b

mt c m ha l t hn so vi tng s mu trong mt tp tin m thanh.

Hnh 3.1 Phng thc thay th bt trong thut ton LSB

1 1 0 1 0 0 0 0

0 1 0 1 0 1 0 1

1 1 0 1 0 1 0 0

0 1 0 1 0 0 0 1

1 1 0 1 0 1 0 0

0 1 0 1 0 0 0 0

1 1 0 1 0 1 0 1

0 1 0 1 0 0 0 1

1

0

0

1

1

0

1

0

1 1 0 1 0 0 0 1

0 1 0 1 0 1 0 0

1 1 0 1 0 1 0 0

0 1 0 1 0 0 0 1

1 1 0 1 0 1 0 1

0 1 0 1 0 0 0 0

1 1 0 1 0 1 0 1

0 1 0 1 0 0 0 1

44

2. Thut ton nhng d liu trn nn m thanh s dng phng php m ha LSB.

2.1 Tin x l thut ton giu v tch tin LSB.

c th xy dng chng trnh, trc ht cn tm hiu mt s hm thnh phn

vi mc ch ci t chng trnh thun li:

- Hm chuyn i t chui k t sang s nh phn.

- Hm chuyn i t chui s nh phn sang chui k t.

Tm tt thut ton thay th LSB n gin

2.2 Thut ton giu tin.

u vo:

- Tp tin m thanh nh dng .wav.

- Thng ip b mt (nh dng .text).

- Kha b mt (nh dng text c chiu di khng ln hn 8 k t).

u ra:

- File m thanh mang tin.

Cc bc thc hin:

Bc 1: c tp tin m thanh cha c giu thng tin b mt.

Bc 2: B 44 bytes u tin ca tp tin v y l phn header ca tp tin m

thanh.

Bc 3: Chuyn thng tin b mt sang dng nh phn.

Bc 4: Chuyn di thng tin b mt sang dng nh phn.

Bc 5: Chuyn kha b mt sang dng nh phn 8 bt. Kha b mt gip bo v v

nhn din tp tin m thanh c giu thng tin b mt.

Bc 6: Kha b mt c giu trong 8 mu d liu u tin. Nu khng c kha

b mt th tp tin m thanh s khng giu thng tin b mt.

Bc 7: 10 mu d liu tip theo s dng giu chiu di ca thng tin b mt.

45

Bc 8: 10 mu d liu tip theo s dng giu chiu rng ca thng tin b mt.

Bc 9: Thng tin b mt s c giu trong cc mu tip theo cho n ht chiu

di ca thng tin b mt dng nh phn.

2.3 Thut ton tch tin.

u vo:

- Tp tin m thanh nh dng .wav c giu thng tin mt.

- Kha b mt (nh dng text c chiu di khng ln hn 8 k t).

u ra:

- Thng tin b mt c tch.

Cc bc thc hin:

Bc 1: c tp tin m thanh c giu thng tin b mt.

Bc 2: B qua 44 bytes u tin ca tp tin v y l phn header ca tp tin m

thanh, ch ly phn mu d liu m thanh.

Bc 3: Chuyn kha b mt sang dng nh phn 8 bit.

Bc 4: Kim tra xem kha b mt c trng vi 8 bit tch t 8 mu u tin ca d

liu m thanh khng. Nu khng th tp tin m thanh cha c nhng hoc mt

khu khng ng.

Bc 5: Kch thc ca thng tin b mt s c ly t 20 mu d liu tip theo.

Bc 6: T kch thc ca thng tin mt tnh c chiu di ca thng tin mt

di dng nh phn .

Bc 7: Ly cc bt ca thng tin b mt cc mu d liu tip theo cho n ht

chiu di ca thng tin b mt di dng nh phn.

Bc 8: Chuyn thng tin b mt t nh phn sang dng k t.

2.4 u im ca k thut m ha LSB

46

l cch n gin nht che giu thng tin trong mt tp tin m thanh. N cho

php s lng ln cc d liu c giu trong mt tp tin m thanh. K thut m ha

LSB thng khng to ra thay i nhiu trong tp tin m thanh

2.5 Nhc im ca k thut m ha LSB.

Thng tin b mt d b tn tht trc cc kiu tn cng thng thng nh ly li

mu, lc thng, bin i tn hiu t tng t sang s hoc ngc li..

3. Ci t v th nghim chng trnh.

3. 1. Mi trng ci t

Ngn ng ci t, mi trng son tho v chy chng trnh c thc hin trn

ngn ng lp trnh Matlap 2009b.

H iu hnh Window 7 v mi trng Net FrameWork 4.0.

Giao din ca chng trnh:

Hnh 3.2 Giao din chnh ca chng trnh

Quy trnh giu tin:

47

u tin chn ch Nhng d liu trong khung La Chn. Nhn vo

nt Chon File chn tp tin audio.

Hnh 3.3 Chn tp tin audio.

Thng tin mt cn giu chng ta c th nh trc tip vo edit text trong

khung d liu c nhng hoc nhn nt Chon File chn file text mun

nhng.

nh kha bo mt vo Mat Khau. Lu kha bo mt khng di hn 8

k t.

Bm nt Nhung Du Lieu thc hin nhng d liu.

Hnh nh qu sau khi nhng thnh cng s nh sau:

48

Hnh 3.4 Nhng d liu thnh cng

File m thanh sau khi nhng s c lu trong th mc vi phn ci t

chng trnh v ly tn l New_ngay_gio_phut nhng d liu. V d

New_08-jan-2015_11_4.wav.

Sau khi thc hin giu tin thnh cng, u ra s bao gm:

Thng bo Giu tin thnh cng!.

Kha bo mt cn.

File m thanh giu tin.

Quy trnh tch tin.

nh kha bo mt vo Mat Khau.

Chn ch Khi Phc D Liu trong khung la chn. Sau bm nt Chon

File chn file nhc c nhng d liu.

49

Hnh 3.5 Quy trnh hi phc d liu

Nu kha bo mt ng th thng tin mt s c hin trong ln trong

khung Du Liu Duoc Phuc Hoi.

Hnh 3.6 D liu c phc hi thnh cng

Nu d liu khng c phc hi thnh cng do kha bo mt sai hoc tp

tin m thanh cha c nhng d liu.

50

Hnh 3.7 Thng bo khi phc d liu tht bi

Ghi m.

to mt tp tin m thanh nhng d liu ngi dng c th dng chc nng

ghi m to mt tp tin m thanh mnh mong mun.

thc hin chc nng ny ngi dng cn thc hin cc bc sau:

La chn thi gian mong mun vo bng cc nh thi gian (n v s) vo

Thoi Gian.

Bm nt Ghi Am bt u ghi m.

Sau khi vic ghi m hon tt th s hin ra:

Chng ta nh tn mnh mun lu ri bm nt Save hon tt.

Bt, tt tp tin m thanh.

Bm nt Mo Audio. Sau la chn tp tin m thnh cn m ri bm nt

Open.

51

Hnh 3.8 M tp tin m thanh.

tt th bm nt Tat trn giao din ca chng trnh.

3.3 So snh ph bin ca m thanh trc v sau khi nhng d liu.

Hinh 3.9 Ph bin m thanh trc khi nhng d liu.

52


Nhn xt ph bin d m thanh trc v sau khi nhng khng c thay i nhiu.

3.4 nh gi v chng trnh.

u im:

Chng trnh chy tt, d dng s dng.

Thng tin mt trc khi nhng v sau khi nhng hon ton ging nhau.

Cht lng m thanh trc v sau khi nhng khng thay i nhiu, lm cho

ngi nghe rt kh pht hin.

Nhc im:

Chng trnh ch thc hin c vi tp tin m thanh nh dng wav, v d

liu ca thng tin b mt l tp tin nh dng text.

Giao din chng trnh cha hp l.

Thut ton thc hin trong chng trnh n gin.

Mc bo mt ca kha bo v cn thp.

Hng pht trin ca chng trnh.

53

Nng cp thut ton vic bo mt tt hn, trnh c tc ng ca bn

ngoi.

Xy dng chng trnh c th thc hin vi file c cc nh dng khc nh

.mp3. V thng tin mt cn nhng c th m rng ra vi hnh nh, audio..

4. Xy dng m hnh truyn d liu qua wifi.

4.1 Giao thc TCP.

Giao thc TCP (Transmission Control Protocol - " Giao thc iu khin truyn

vn") l mt trong cc giao thc ct li ca b giao thc TCP/IP. S dng TCP, cc ng

dng trn cc my ch c ni mng c th to cc "kt ni" vi nhau, m qua chng

c th trao i d liu hoc cc gi tin. Giao thc ny m bo chuyn giao d liu ti

ni nhn mt cch ng tin cy v ng th t TCP cn phn bit gia d liu ca nhiu

ng dng (chng hn, dch v Web v dch v th in t) ng thi chy trn cng mt

my ch.

Trong b giao thc TCP/IP, TCP l tng trung gian gia giao thc IP bn di v

mt ng dng bn trn. Cc ng dng thng cn cc kt ni ng tin cy kiu ng

ng lin lc vi nhau, trong khi , giao thc IP khng cung cp nhng dng kiu ,

m ch cung cp dch v chuyn gi tin khng ng tin cy. TCP lm nhim v ca tng

giao vn trong m hnh OSI n gin ca cc mng my tnh.

Thit lp kt ni

thit lp mt kt ni, TCP s dng mt quy trnh bt tay 3 bc (3-way handshake)

Trc khi client th kt ni vi mt server, server phi ng k mt cng v m cng

cho cc kt ni: y c gi l m b ng. Mt khi m b ng c thit lp th

mt client c th bt u m ch ng. thit lp mt kt ni, quy trnh bt tay 3 bc

xy ra nh sau:

1. Client yu cu m cng dch v bng cch gi gi tin SYN (gi tin TCP) ti

server, trong gi tin ny, tham s sequence number c gn cho mt gi tr ngu

nhin X.

http://vi.wikipedia.org/wiki/TCP/IPhttp://vi.wikipedia.org/w/index.php?title=Gi_tin&action=edit&redlink=1http://vi.wikipedia.org/wiki/IPhttp://vi.wikipedia.org/w/index.php?title=?ng_d?ng_ph?n_m?m&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=???ng_?ng&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=???ng_?ng&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=Khng_?ng_tin_c?y&action=edit&redlink=1http://vi.wikipedia.org/wiki/T?ng_giao_v?nhttp://vi.wikipedia.org/wiki/T?ng_giao_v?nhttp://vi.wikipedia.org/wiki/M_hnh_OSIhttp://vi.wikipedia.org/wiki/M?ng_my_tnhhttp://vi.wikipedia.org/w/index.php?title=B?t_tay_(tin_h?c)&action=edit&redlink=1

54

2. Server hi p bng cch gi li pha client bn tin SYN-ACK, trong gi tin ny,

tham s acknowledgment number c gn gi tr bng X + 1, tham s sequence

number c gn ngu nhin mt gi tr Y

3. hon tt qu trnh bt tay ba bc, client tip tc gi ti server bn tin ACK,

trong bn tin ny, tham s sequence number c gn cho gi tr bng X + 1 cn

tham s acknowledgment number c gn gi tr bng Y + 1

Ti thi im ny, c client v server u c xc nhn rng, mt kt ni c

thit lp.

Truyn d liu

Mt s c im c bn ca TCP phn bit vi UDP:

Truyn d liu khng li (do c c ch sa li/truyn li)

Truyn cc gi d liu theo ng th t

Truyn li cc gi d liu mt trn ng truyn

Loi b cc gi d liu trng lp

C ch hn ch tc nghn ng truyn

hai bc u tin trong ba bc bt tay, hai my tnh trao i mt s th t gi ban

u (Initial Sequence Number -ISN). S ny c th chn mt cch ngu nhin. S th t

ny c dng nh du cc khi d liu gi t mi my tnh. Sau mi byte c

truyn i, s ny li c tng ln. Nh vy ta c th sp xp li chng khi ti my tnh

kia bt k cc gi ti ni theo th t th no.

Trn l thuyt, mi byte gi i u c mt s th t v khi nhn c th my tnh

nhn gi li tin bo nhn (ACK). Trong thc t th ch c byte d liu u tin c gn

s th t trong trng s th t ca gi tin v bn nhn s gi tin bo nhn bng cch gi

s th t ca byte ang ch.

http://vi.wikipedia.org/wiki/UDP

55

Cc cng TCP

TCP s dng khi nim s hiu cng (port number) nh danh cc ng dng

gi v nhn d liu. Mi u ca mt kt ni TCP c mt s hiu cng (l s khng du

16-bit) c gn cho ng dng ang nhn hoc gi d liu. Cc cng c phn thnh ba

loi c bn: ni ting, c ng k v ng/c nhn. Cc cng ni ting c gn bi

t chc Internet Assigned Numbers Authority (IANA) v thng c s dng bi cc

tin trnh mc h thng hoc cc tin trnh ca root. V d: FTP (21), TELNET (23),

SMTP (25) v HTTP (80). Cc cng c ng k thng c s dng bi cc ng

dng ngi dng u cui (end user application) vi vai tr cc cng pht tm thi (khi

dng xong th hy ng k) khi kt ni vi server, nhng chng cng c th nh danh

cc dch v c tn c ng k bi mt bn th ba. Cc cng ng/c nhn cng c

th c s dng bi cc ng dng ngi dng u cui, nhng khng thng dng bng.

Cc cng ng/c nhn khng c ngha g nu khng t trong mt kt ni TCP. C

65535 cng c chnh thc tha nhn.

4.2 Xy dng m hnh truyn d liu qua wifi trn phn mm GNU Radio.

4.2.1 Thit lp my ch.

Hnh 3.11 S thit lp kt ni ca my ch.

Chc nng ca cc khi.

http://vi.wikipedia.org/w/index.php?title=C?ng_(tin_h?c)&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=Internet_Assigned_Numbers_Authority&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=Root&action=edit&redlink=1http://vi.wikipedia.org/wiki/FTPhttp://vi.wikipedia.org/wiki/Telnethttp://vi.wikipedia.org/wiki/SMTPhttp://vi.wikipedia.org/wiki/Hypertext_Transfer_Protocol

56

Wav File Source: Ly d liu ca tp tin m thanh c nh dng Wav.

Wx GUI FFT Sink: M t ph ca tn hiu m thanh.

Variable: Khai bo gi tr ca tn s ly mu.

Throttle: iu khin tc ly mu.

TCP Sink: Dng thit lp ng truyn.

Cc tham s trong khi TCP Sink:

Input Type: Kiu d liu u vo.

Adrress: a ch IP my ca bn.

Port: Tn cng dng kt ni.

Mode: Ch l my ch hay l khch.

Chng trnh s khng bt u cho n khi mt kt ni TCP c thit lp. V

vy, ph tn hiu khng xut hin cho n khi c my khc kt ni thnh cng.

4.2.2 Thit lp my khch.

Hnh 3.12 S thit lp kt ni ca my khch.

Chc nng ca cc khi:

Variable: Thit lp thng s ca tn s ly mu.

Wx GUI FFT Sink: M t ph ca tn hiu m thanh.

57

Audio Sink: Pht tn hiu m thanh trn loa ca my tnh.

Wav File Sink: Ghi tp tn hiu m thanh thnh mt tp tin mi.

TCP Source: Thit lp ng truyn.

Cc thng s trong khi TCP Source:

Output Type: Kiu d liu u ra.

Address: a ch IP ca my ch

Port: Tn cng ca my ch thit lp.

Mode: Ch , chn Client.

Nu kt ni TCP tht bi, chng trnh s khng chy, v ph tn hiu s khng

xut hin.

5 M hnh th nghim truyn thng tin b mt qua wifi.

wifi

Hnh 3.13 M hnh th nghim truyn thng tin b mt qua wifi.

Trc tin chng ta nhng tp tin DHBK.text c ni dung l Dai Hoc Bach Khoa Ha

Noi vo tp tin GhiAm.wav c tp tin sau khi nhng l: New_10-Jan-

2015_8_51.wav

TCP

Source

Kha

b mt

Audio cha

thng tin b

mt

B

tch

d liu

Thng

tin b

mt

B

nhng

d liu

Audio

gc

Thng

tin b

mt

Kha

b mt

Audio cha

thng tin b

mt

TCP

Sink

58

Truyn tp tin New_10_Jan_2015_8_51.wav qua m hnh truyn d liu qua wifi.

Hnh 3.14 Truyn tp tin New_10_Jan_2015_8_51.wav.

Bn thu nhn c tp tin wifi.wav.

Hnh 3.15 Bn thu nhn c tp tin wifi.wav

Sau ta tch d liu trong hai tp tin c kt qu nh sau:

Kt qu tch d liu t tp tin New_10_Jan_2015_8_51.wav

59

Hnh 3.16 Kt qu tch thng tin b mt t tp tin New_10_Jan_2015_8_51.wav

Kt qu tch d liu t tp tin wifi.wav.

Hnh 3.17 Kt qu tch thng tin b mt t tp tin wifi.wav

60

Nhn xt.

Sau khi truyn qua m hnh truyn nhn d liu qua wifi d liu c tch ra hon

ton ging vi d liu nhng ban u.

5 Tm tt chng.

Chng ny phn tch thut ton nhng v tch d liu trong m thanh d trn k

thut m ha LSB, t xy dng c chng trnh nhng d liu trong m thanh

trn phn mm Matlab. Ngoi ra cn xy dng c m hnh truyn d liu qua wifi v

chy thnh cng.

61

Chng 4 Kt Lun.

Hin nay nhng (giu) d liu trn nn tn hiu m thanh l mt b phn chim t

l ln trong cc chng trnh ng dng h thng nhng d liu trong a phng tin bi

lng d liu c trao i bng m thanh l rt ln v hn na nhng d liu trn nn

tn hiu m thanh cng ng vai tr ht sc trng trong hu ht cc ng dng bo v an

ton thng tin. Chnh v th m vn ny nhn c s quan tm rt ln ca cc c

nhn, t chc, trng i hc v nhiu vin nghin cu trn th gii. Trong n ny tm

hiu v: Nhng d liu trn nn tn hiu m thanh da trn cng ngh nh ngha bng

phn mm. C th n t c cc kt qu sau.

Nhng iu t c.

-Nghin cu v cng ngh v tuyn nh ngha bng phn mm v cc ng dng.

-Nghin cu cu trc tp tin m thanh .wav.

-Tm hiu k thut giu tin trong audio c th l k thut m ha LSB.

- Xy dng v thc nghim thnh cng chng trnh nhng d liu dng text trong

tp tin m thanh trn phn mm Matlab 2009b.

-Xy dng c m hnh thu, pht d liu bng wifi da trn cng ngh v tuyn

nh ngha bng phn mm.

-Tp tin m thanh sau khi c nhng khi truyn qua m hnh thu, pht d liu

trn c th tch c thng tin nhng.

Nhng hn ch.

-Phn mm cn nhiu hn ch mi nhng c d liu dng text v tp tin m

thanh nh dng wav.

-Thut ton nhng cn n gin, thng tin d b thay i, tn tht do cc kiu tn

cng thng thng.

-M hnh thu, pht cn hn ch ch dng c trong phm vi hp.

Hng pht trin ca ti.

62

-Xy dng chng trnh hon thin hn, d liu nhng a dng hn.

-Xy dng thut ton phc tp hn d liu bn vng trc cc kiu tn cng.

-Xy dng m hnh thu pht phc tp hn, c ng dng phm vi rng hn.

V thi gian nghin cu c hn, trnh hiu bit ca bn thn em cn nhiu hn

ch nn bi bo co ca em khng trnh khi nhng thiu st, em rt mong nhn c s

gp qu bu ca tt c cc thy c gio bo co ca em c hon thin hn.

Em xin chn thnh cm n!

63

Ti liu tham kho

[1] GNU Radio, http://www.gnu.org/software/gnuradio/.

[2] NGUYN TH HNH, Thy vn c s d liu quan h da trn k thut thi u

ha p dng thut ton tm kim theo mu, Lun vn thc s khoa hc my tnh.

[3] http://www.mathworks.com/help/matlab/.

[4] Duc Toan Nguyen, Implementation of OFDM systems using GNU Radio and

USRP, This thesis is presented as part of the requirements for the award of the Degree

of Master by Research - Engineering from University of Wollongong.

[5] Nguyn Vn c, L thuyt v Knh V Tuyn, Nh xut bn Khoa Hc v K

Thut, 2006.

[6] Prof. Samir Kumar, BandyopadhyayBarnali, Gupta Banik, LSB Modification and

Phase Encoding Technique of Audio Steganography Revisited, Department of

Computer Science and Engineering, University of Calcutta, Kolkata India. Department of

Computer Science, St Thomas College of Engineering & Technology, Kolkata India

[7] Kirti Gandhi, Gaurav Garg, Modified LSB Audio Steganography Approach,

International Journal of Emerging Technology and Advanced Engineering.

[8] http://www.tenettech.com/product/3127/usrp-b210.

[9] Kamred Udham Singh, LSB Audio Steganography Approach, International

Journal of Emerging Technology and Advanced Engineering .

Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume

4, Issue 4, April 2014).

[10] K.P.Adhiya, Swati A. Patil, Hiding Text in Audio Using LSB Based

Steganography, Information and Knowledge Management ISSN 2224-5758 (Paper)

ISSN 2224-896X (Online)Vol 2, No.3, 2012.

http://www.gnu.org/software/gnuradio/http://www.mathworks.com/help/matlab/http://www.tenettech.com/product/3127/usrp-b210

64

Ph Lc

Code phn mm vit bng Matlab.

function varargout = NhungDuLieu(varargin) % NHUNGDULIEU M-file for NhungDuLieu.fig % NHUNGDULIEU, by itself, creates a new NHUNGDULIEU or raises the

existing % singleton*. % H = NHUNGDULIEU returns the handle to a new NHUNGDULIEU or the handle

to existing singleton*. % % NHUNGDULIEU('CALLBACK',hObject,eventData,handles,...) calls the local function named CALLBACK in NHUNGDULIEU.M with the given input arguments. % NHUNGDULIEU('Property','Value',...) creates a new NHUNGDULIEU or raises the % existing singleton*. Starting from the left, property value pairs are % applied to the GUI before audiostegano_OpeningFunction gets called.

An % unrecognized property name or invalid value makes property application % stop. All inputs are passed to NhungDuLieu_OpeningFcn via varargin. % % *See GUI Options on GUIDE's Tools menu. Choose "GUI allows only one % instance to run (singleton)". % % See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help NhungDuLieu

% Last Modified by GUIDE v2.5 01-Jan-2015 19:54:27

% Begin initialization code - DO NOT EDIT gui_Singleton = 1; gui_State = struct('gui_Name', mfilename, ... 'gui_Singleton', gui_Singleton, ... 'gui_OpeningFcn', @NhungDuLieu_OpeningFcn, ... 'gui_OutputFcn', @NhungDuLieu_OutputFcn, ... 'gui_LayoutFcn', [] , ... 'gui_Callback', []); if nargin && ischar(varargin{1}) gui_State.gui_Callback = str2func(varargin{1}); end

if nargout [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:}); else gui_mainfcn(gui_State, varargin{:}); end % End initialization code - DO NOT EDIT % --- Executes just before NhungDuLieu is made visible. function NhungDuLieu_OpeningFcn(hObject, eventdata, handles, varargin) % This function has no output args, see OutputFcn. % hObject handle to figure % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA)

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% Choose default command line output for NhungDuLieu handles.output = hObject; handles.fname=''; handles.pname=''; set(handles.pushbutton2,'enable','off'); set(handles.txt1,'string',''); guidata(hObject, handles);

% --- Outputs from this function are returned to the command line. function varargout = NhungDuLieu_OutputFcn(hObject, eventdata, handles) % varargout cell array for returning output args (see VARARGOUT); % hObject handle to figure % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % Get default command line output from handles structure varargout{1} = handles.output; function edit1_Callback(hObject, eventdata, handles) % hObject handle to edit1 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % --- Executes during object creation, after setting all properties. function edit1_CreateFcn(hObject, eventdata, handles) % hObject handle to edit1 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles empty - handles not created until after all CreateFcns called % Hint: edit controls usually have a white background on Windows. % See ISPC and COMPUTER. if ispc && isequal(get(hObject,'BackgroundColor'),

get(0,'defaultUicontrolBackgroundColor')) set(hObject,'BackgroundColor','white'); end % --- Executes on button press in pushbutton1. function pushbutton1_Callback(hObject, eventdata, handles) % hObject handle to pushbutton1 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) value1=get(handles.radiobutton1,'value'); value2=get(handles.radiobutton2,'value'); if value1==1 [handles.fname, handles.pname] = uigetfile('*.wav','Chon File'); set(handles.pushbutton2,'enable','on'); set(handles.pushbutton1,'enable','off'); set(handles.txt1,'string','Nhung Du Lieu'); guidata(hObject, handles); %Cp nht cu trc x l. end if value2==1

mke=get(handles.edit5,'string');% Ly mt khu if length(mke)==0 msgbox('Vui Long Nhap Mat Khau','Thong Bao','error'); else if length(mke)>8 msgbox('Mat Khau Nhieu Hon 8 Ky Tu. Vui Long Nhap Lai','Thong

Bao','error');

else

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mke_num=double(mke); mke_binvec=dec2binvec(mke_num,8); set(handles.pushbutton2,'enable','off'); set(handles.txt1,'string','Khoi Phuc Du Lieu'); [filename, pathname] = uigetfile('*.wav','Chon File'); [y,fs,nbits,opts]=wavread([pathname filename],[1 2]); %M tp tin m thanh nhng d liu. fid1=fopen([pathname filename],'r'); header=fread(fid1,40,'uint8=>char'); data_size=fread(fid1,1,'uint32'); %c mu d liu ca ca tp tin m thanh [dta,count]=fread(fid1,inf,'uint16'); %ng tp tin m thanh, ch mu d liu wav c trch xut tch ly

d liu. fclose(fid1);

lsb=1;

identity=bitget(dta(1:8),lsb)'; %chui nhn dng tp tin c nhng

hay cha if identity==mke_binvec %Ly chiu di ca thng tin mt t mu th 9 n 28. len_bin=zeros(20,1); m_bin=zeros(10,1); n_bin=zeros(10,1);

m_bin(1:10)=bitget(dta(9:18),lsb); n_bin(1:10)=bitget(dta(19:28),lsb); %chuyn di sang h thp phn. m=bi2de(m_bin'); n=bi2de(n_bin'); len=m*n*8;

secmsg_bin=zeros(len,1); %Ly thng tin mt t mu d liu th 29 cho ti ht chiu di thng

tin mt secmsg_bin(1:len)=bitget(dta(29:28+len),lsb); secmsg_bin_re=reshape(secmsg_bin,len/8,8); secmsg_double=bi2de(secmsg_bin_re); %Chuyn sang h thp phn

secmsg=char(reshape(secmsg_double,m,n)); %chuyn sang kiu k t set(handles.edit2,'string',secmsg); % hin th thng tin c tch ra

trn set(handles.edit5,'string','');

else msgbox('File Chua Duoc Nhung Du Lieu Hoac Mat Khau Khong Dung.','Thong

Bao','error'); end end end end % --- Executes on button press in pushbutton2. function pushbutton2_Callback(hObject, eventdata, handles) % hObject handle to pushbutton2 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB

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% handles structure with handles and user data (see GUIDATA) set(handles.pushbutton1,'enable','on'); msg=get(handles.edit1,'string'); mkh=get(handles.edit5,'string');

curtime = clock(); curfilename = strcat

(date(),'_',num2str(curtime(4)),'_',num2str(curtime(5)),'.wav');

if (length(msg)==0||length(mkh)==0); msgbox('Vui Long Nhap Du Lieu Can Nhung Va Mat Khau','Thong

Bao','error'); else if length(mkh)>8 msgbox('Mat Khau Nhieu Hon 8 Ky Tu. Vui Long Nhap Lai','Thong

Bao','error');

else

mkh_num=double(mkh); mkh_binvec=dec2binvec(mkh_num,8); [y,fs,nbits,opts]=wavread([handles.pname handles.fname],[1 2]); %M tp tin m thanh nhng thng tin mt. fid1=fopen([handles.pname handles.fname],'r');

%40 byte u tin l d liu khi to ca file m thanh header=fread(fid1,40,'uint8=>char');

%data_size=fread(fid1,1,'uint32');

% sao chp cc mu d liu 16 bit bt u t byte th 44

[dta,count]=fread(fid1,inf,'uint16');

%o fclose(fid1); lsb=1; msg=get(handles.edit1,'string'); %ly thng tin mt cn nhng t

edittext [ro,co]=size(msg); if ( (ro*co*8+28) > count ) msgbox('Dung Luong File Qua Lon, Chon File Co Dung Luong Nho Hon','Canh

Bao'); else [m_msg,n_msg]=size(msg); msg_double=double(msg); %Chuyn sang dng s thc msg_bin=de2bi(msg_double,8); %chuyn tin thng tin mt sang

dng nh phn [m,n]=size(msg_bin); %kch thc ca thng tin nh

phn msg_bin_re=reshape(msg_bin,m*n,1); %chuyn thng tin nh phn v

dng 1 ct m_bin=de2bi(m_msg,10)'; n_bin=de2bi(n_msg,10)';

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len=length(msg_bin_re); %chiu di ca thng tin mt nh phn c

chuyn v dng 1 ct

identity=mkh_binvec'; dta(1:8)=bitset(dta(1:8),lsb,identity(1:8));

%nhng chiu di ca thng tin mt di dng nh phn vo mu th 9

n 28 dta(9:18)=bitset(dta(9:18),lsb,m_bin(1:10)); dta(19:28)=bitset(dta(19:28),lsb,n_bin(1:10)); %Giu thng tin mt dng nh phn vo mu th 28 n ht chiu

dithng tin mt dng nh phn dta(29:28+len)=bitset(dta(29:28+len),lsb,msg_bin(1:len)'); %khi o tp tin m thanh mi. fid2=fopen(['New_' curfilename],'w');

%sao chp header tp tin m thanh ban u. fwrite(fid2,header,'uint8'); fwrite(fid2,data_size,'uint32');

%sao chp mu d liu m thanh c nhng d liu. fwrite(fid2,dta,'uint16'); fclose(fid2); msgbox(['Du Lieu Ban Da Nhung Trong File New_' curfilename],''); set(hObject,'enable','off'); set(handles.edit5,'string',''); end end end

% --- Executes on button press in radiobutton2. function radiobutton2_Callback(hObject, eventdata, handles) % hObject handle to radiobutton2 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % Hint: get(hObject,'Value') returns toggle state of radiobutton2 set(hObject,'value',2); set(handles.pushbutton2,'enable','off');

% --- Executes on button press in radiobutton1. function radiobutton1_Callback(hObject, eventdata, handles) % hObject handle to radiobutton1 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % Hint: get(hObject,'Value') returns toggle state of radiobutton1 set(hObject,'value',1);

function edit2_Callback(hObject, eventdata, handles) % hObject handle to edit2 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA)

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% Hints: get(hObject,'String') returns contents of edit2 as text% ---

Executes during object creation, after setting all properties. function edit2_CreateFcn(hObject, eventdata, handles) % hObject handle to edit2 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows. % See ISPC and COMPUTER. if ispc && isequal(get(hObject,'BackgroundColor'),

get(0,'defaultUicontrolBackgroundColor')) set(hObject,'BackgroundColor','white'); end

% --- Executes on button press in pushbutton3. function pushbutton3_Callback(hObject, eventdata, handles) % hObject handle to pushbutton3 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) %close all; cl = questdlg('Ban Co Muon Thoat Khoi Chuong Trinh?','Thoat',... 'Co','Khong','Khong'); switch cl case 'Co' close all; clear all; return; case 'Khong' quit cancel; end

% --- Executes on button press in pushbutton4. function pushbutton4_Callback(hObject, eventdata, handles) % hObject handle to pushbutton4 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) set(handles.edit1,'string','');

% --- Executes on button press in pushbutton5. function pushbutton5_Callback(hObject, eventdata, handles) % hObject handle to pushbutton5 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) set(handles.edit2,'string','');

% --- Executes on button press in pushbutton9. function pushbutton9_Callback(hObject, eventdata, handles) % hObject handle to pushbutton9 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA)


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[FileName,PathName] = uigetfile({'*.wav'},'Chon File Wav'); [x,Fs] = wavread([PathName , FileName]); samp_len = length(x)/Fs; delta_t = 1/Fs; t = 0:delta_t:(samp_len-delta_t); figure; plot(t,x), xlabel('Time [sec]'), ylabel('Amplitude') title('Pho Bien Do'); sound(x,Fs);

% --- Executes on button press in pushbutton14. function pushbutton14_Callback(hObject, eventdata, handles) % hObject handle to pushbutton14 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) clear playsnd;


fs = 44100; len=get(handles.edit4,'string');

if(length(len)==0) msgbox('Chua Nhap Thoi Gian','Thong Bao','error'); else

lengh=str2num(len); legh=double(lengh); y = wavrecord(legh*44100,fs,'int16'); [filename, pathname] = uiputfile('*.wav', 'Luu File'); cd (pathname); wavwrite(y,fs,filename); set(handles.edit4,'string',''); end

function edit3_Callback(hObject, eventdata, handles) % hObject handle to edit3 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % Hints: get(hObject,'String') returns contents of edit3 as text % str2double(get(hObject,'String')) returns contents of edit3 as a % double % --- Executes during object creation, after setting all properties.

% --- Executes on button press in pushbutton18. function pushbutton18_Callback(hObject, eventdata, handles) % hObject handle to pushbutton18 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) [filename, pathname]=uigetfile({'*.txt'},'Chon File'); fullpathname=strcat( pathname,filename);

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text=fileread(fullpathname); set(handles.edit1,'String',text)

% --- Executes on button press in pushbutton19. function pushbutton19_Callback(hObject, eventdata, handles) % hObject handle to pushbutton19 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) [filename, pathname] = uiputfile('*.txt','Luu file'); lmsg=get(handles.edit2,'string'); if length(lmsg)==0 msgbox('Khong Co Du Lieu De Luu','Thong Bao','error'); else fid = fopen( filename,'wt'); fprintf(fid,lmsg) fclose(fid); end

% --- Executes during object creation, after setting all properties. function slider4_CreateFcn(hObject, eventdata, handles) % hObject handle to slider4 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles empty - handles not created until after all CreateFcns called

% Hint: slider controls usually have a light gray background. if isequal(get(hObject,'BackgroundColor'),

get(0,'defaultUicontrolBackgroundColor')) set(hObject,'BackgroundColor',[.9 .9 .9]); end

function edit4_Callback(hObject, eventdata, handles) % hObject handle to edit4 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % Hints: get(hObject,'String') returns contents of edit4 as text % str2double(get(hObject,'String')) returns contents of edit4 as a

double

% --- Executes during object creation, after setting all properties. function edit4_CreateFcn(hObject, eventdata, handles) % hObject handle to edit4 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows. % See ISPC and COMPUTER. if ispc && isequal(get(hObject,'BackgroundColor'),

get(0,'defaultUicontrolBackgroundColor')) set(hObject,'BackgroundColor','white'); end

function edit5_Callback(hObject, eventdata, handles) % hObject handle to edit5 (see GCBO) % eventdata res

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