novel algorithm adm (1)

7/25/2019 Novel Algorithm ADM (1)

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Study of a Novel ADM Algorithm

with Pre-processing forPerformance Improvement

byB!Su"atha

MS #amaiah Institute of $echnology% Bangalore

&uide' (o-&uide'

Prof Dr PS Satyanarayana ProfDr ! N )aribhat$he )ead% Dept of *lectronics +(omm *ngg $he )ead% Dept of $elecomm*ngg

BM Sreenivasaih (ollege of *ngineering Nagar"una (ollege of *ngg and$ech

Bangalore Bangalore


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$opics

SPEECH CODING

DISCRIPTION OF EACH CODING TECHNIQUE

ADAPTIVE DELTA MODULATION

PRE-PROCESSING

STEP SIZE ALGORITHMEXISTING STEP SIZE ALGORITHMS

SONG ALGORITHM

MODIFIED ABATE ALGORITHM

PROPOSED ALGORITHM

CONCLUSION

BIBLIOGRAPHY


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AD,AN$A&*S AND DIS-AD,AN$A&*S . DI&I$A/

(MM0NI(A$INADVANTAGES: Less distortion in the received signal. Simple and less expensive digital circuitry.

ossi!ility o" processing digital signals. #etter received speech $uality. ossi!ility o" transmission o" voice%video%data all in digital

"orm. ossi!ility o" correction o" medium errors. Encryption&decryption "or message security.D'S(ADVANTAGES: 'ncreased !and)idth.

Synchroni*ation re$uirement.


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SP**() (DIN&+onversion o" analog speech signals into

digital "orm

$ypes of speech coding'

ulse +ode ,odulation Di-erential ulse +ode ,odulationD+,/

Delta ,odulationD,/ Adaptive Delta ,odulationAD,/


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P0/S* (D* MD0/A$IN

Steps involved in P(M ' Sampling 0uanti*ing

Encoding

n 1 log2

L#and)idth o" +, depends on !it rate% 3 1 n"s

4or no aliasing% "s 51 2 "m #+,51 6 3 1 6 n"s


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DI..*#*N$IA/ P0/S*

(D* MD0/A$IN To minimi*e redundant transmission

To reduce the !and)idth in comparison)ith +,


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D*/$A MD0/A$IN

N* BI$ # $1 /*,*/ ,*#SIN . DP(M'This one(!it code)ord eliminates the need "or7 )or"raming8 at the transmitter 9 receiver 9 maes D,

systems very attractive "or many classes o" digitalcommunications.

NIS* IN DM '

Smaller step si*e causes slope overload distortion. Larger step si*e causes granular noise.


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D, ;AVE4


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/IMI$A$INS . DM

m(t)

stair case approximate m(t)

Max slope

overload

Slope overload (positive)

^

/IMI$A$INS . DM


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m(t)

m(t)

Negative slope overload

Slope overload (negative)

^

/IMI$A$INS . DM2contd3


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m(t)

m(t)

Granular no!"

(slow varying signal)

/IMI$A$INS . DM

2contd3

^


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ADAP$I,* D*/$A MD0/A$IN 'mproved version o" D, !y maing the step

si*e o" the modulator assume a time

varying "orm.

=ere the step si*e is adapted to the level o"the input signal


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ADM 1A,*.#MS


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Sample speech signal

The sample speech )ave"orm in theillustration is taen "rom the speech sound >i ii i i? )hich is sho)n in 4igure. 't is one o" the)ave"orms used repeatedly in the simulationthat is a!out @s long.


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Pre-Processing

A methodology "or "urther improving the AD,per"ormance !y pre(processing the speechsignal prior to the adaptation is presented.

The large variations in the speech areremoved&smoothened !y a suita!le pre(processing method% one o" )hich is using an

integrator )hich can smoothen the rapidchanges.At the receiver% the di-erentiator is "ollo)ed

!y a lo) pass lterL4/.


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m(t)

(2)

(1)

(1)Slope overload distorti

n (2)Granu

P#*-P#(*SSIN& . M*SSA&* SI&NA/

#$%&'%!#oo%("! ou% #$%& ) ra*' +(an,"! #a '!a**"ar.

t

m(t) (2)

(1)

(1)Slope overload distortion region

(2)Granular noise region

t


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Frequency response of re!rocessor

("ntegrator) at t#e transmitter

Frequency response of t#e

$ifferentiator at t#e receiver


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ENCODER

DECODER

The block diagram of Conventional ADM


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ENCODER

DECODER

The block diagram of proposed ADM


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S$*P-SI4* A/I$)M'

'n the step(si*e algorithm% the processor detects the

pattern o" et/ )here et/ 1 sgn Bmt/(mt/C To see i" the delta modulator is operating in the

$uanti*ation region% in )hich case et/ produces analternating FF pattern% or in the slope overloadregion in )hich case et/ produces an all 8s or all F8spattern. These cases are illustrated as sho)n.

'" AD, senses a FF pattern% it decreases the step si*e%and i" it senses or FFFF% it increases the stepsi*e . The manner in )hich the step si*e is altereddetermines the algorithm.

^


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/inear delta modulation and the bitpattern produced for each region

t

e(k) 1 01 0 1 0 1 1 1 1 1 1

m(t)

m(t)^


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*5IS$IN& S$*P SI4*ADAP$A$INS

SN& A/I$)M =ere% )e see that as long as e/ is o" the same sign

as e(/% the magnitude o" the ne) step si*e s/)ill exceed the magnitude o" the old step si*e s/ !yso% the Hmin step si*e8.

=o)ever% i" e/ and e(/ di-er in sign % themagnitude o" s/ )ill !e less than the magnitudeo" s/ !y the amount so.

The e$uation descri!ing the song algorithm isgiven !y

Is/I so% e/ 1 e(/Js/J1

Is/ I( so % e/ e(/


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MDI.I*D ABA$* A/I$)M

The need to maintain voice communicationsas long as possi!le )as a ey "actor in the

selection o" the modifed abate algorithm. The e$uation descri!ing modifed abate

algorithm is

BJS/J SoC e/K e/1e(/and S/ MSo

S/1 JS/J e/K e/1e(/and S/ 1 MSo

Soe/K other)ise


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$he Proposed step-si6eadaptation

The ne) proposed techni$ue "or the step(si*e adaptation isdescri!ed as

BJS/JSFCe/K e/1e(/

S/1 BOJS/J(SFCe/K e/Pe(/ and OJ S/J5 SF SFe/ /K e/Pe(/ and OJ S/J SF

is the adaptation parameter% nearly e$ual to !ut% greater than .

O &/


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$he Proposed step-si6e

adaptation 2cont73

This adaptation parameter gives a!etter per"ormance to slope overload

The parameter O taes care o" thegranular noise as a result o" )hich a!etter per"ormance is o!tained as

compared to S


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SIM0/A$INSN# (A/(0/A$IN

QRn samples o" original signal speech signal/

QRn samples o" nal reconstructed signal

Rn ( Rn/ error signal

Rn (R n/2 s$uared error signal

)here N is the total sample num!er o" the input.


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(a)Performance Comparison of the proposed step-size adaptationalgorithm with the SONG and the modified ABATE algorithms.

(b)(b) the same plotof figure.(a) is shown but the input strength isdisplayed for -7db to -1db.

(a) (b


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(a)Performance Comparison of the proposed ADM with the SONG,modified ABATE and the proposed algorithms.

(b) the same plot of figure.(a) is shown but the input strength isdisplayed for -7db to -1db.

(a (b


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(N(/0SIN

Simulations are carried out "or all the schemes. SF istaen as F. and Simulations have also conrmed that)ith the input strength "or (Ud! to (d! on an average a.d# per"ormance gain in the SN3 is got "or the ne)

step(si*e adaptation algorithm compared to the S


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#eferences %1& ' N #ong wan* +wang Soo ,ee* -. study of t#e comparative performance of .daptive $elta

Modulation systems/* "000 ransaction vol 2* 3an 1456 %2& $onald ,* Sc#illing* 3osep# gorodnic7 and +arold .68ang* -8oice encoding for t#e space s#uttle using

.$M/IEEE Trans. on Communications, vol. COM-26* no6 11* Nov 1426

%9&6 G6 S6 om:ras and 6 .6 ary:a7as* -

New adaptation algorit#m for a two!digit adaptive delta modulation system*/ "nternational 3ournal of

0lectronics* vol6 ;* no69* pp69

novel algorithm adm (1)

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