4 "JT'T'T'T

Nghien cufu, thiet ke bp dao tan ien va dao tan xuong cho cac he thong vo tuyen cau hinh mem hieu qua tai nguyen tren cdng nghe FPGA

. ' Tran Van Nghia*

) Tnrdng Dgt hgc Vat ly Ky thuat Matxcova

Ngay nhan b^i 5.10.2015, ngay ehuyen phan bien 9.10.2015, ngay nh^n phan bien 10,11.2015, ngay chip nhan dang 18.11.2015

Bai bao trinh b^y kign true va thirc hien bo dao th\ Ign va dao tan xuong so tren chip FPGA (Field- programmable gate arrays) v ^ tai nguyen t6i uu cd kha nang thich hgp cho su- phat trien ciia cdng nghe vd tuyen c4u hinh m§m. Ky thuSt nay cd the ap dung r^ng rai trong cac irng dung xii' ly tin hi^u so va cac hg thdng thdng tin so. Minh hoa thiet kl cho he thong thu phat dira trgn ky thu^t dieu che QPSK (Quadrature phase shift keying). Thief kg duwc thyc hien b5ng cdng cu System Generator for DSP (Digital signal processing) 14.7.

Tu khoa: bg ddo tdn len, bg ddo tdn xuong, bg Igc bii CFIR (CIC Compensation filter), bg loc CIC (Cascaded integrator-comb filter), dieu che vd gidi dieu che QPSK.

Chi so phdn loai 2.2

RESEARCHING AND DESIGNING THE DIGITAL UP AND DOWN

CONVERTER FOR SOFTWARE I DEFINED RADIO (SDR) SYSTEMS WITH i

EFFICIENT RESOURCES BASED ON ; FPGA TECHNOLOGY I

S u m m a r y %- This paper presents the architecture and implementation of the digital up and down converter | based on a FPGA chip with efficient resources which is well suited for the evolving technology of I software defined radio systems. The divice may be widely adopted in the applications of digital signal processing and digital communication systems. >

Demonstration of transceiver system design is | implemented by using the QPSK modulation { technique. And this design is done by the System f

Generator for DSP 14.7. ? Keywords: CIC filters. Compensation filter CFIR, '-'•

digital down converter, digital up converter, QPSK { mapper and demaper.

Classification number 2.2 ? Dat van dg

Ngay nay, SDR (Software defined radio) duac cac ky su thiet ke he thong vo tuyen dac biet quan tam bai kha nang lap trinh dua tren FPGA [1].

Trong do, thanh ph^n dugc cac ky su tap trung phat trien nhat la cac bo dao tan len va xuong so sao cho toi thieu hoa tai nguyen sii dung nhung dat dugc toe do cao. Chinh vi the, tac gia cua bai bao nay da tap trung thiet ke va thu nghiem bg DDC (Digital down converter) va DUC (Digital up converter) tren eong cu System Generator. Ky thuat diSu che va giai dieu che QPSK dugc lira chgn lam phan xu- ly tin hieu bang co so.

nipi dung nghien cuu Ky thuat diiu chi QPSK

Dieu che QPSK da dugc ung dung rong rai trong cac he thong thong tin so vai mo ta toan hgc nhu sau [2]:

s(t) = Acos(27rfj + 0,), ( = 1,2,3,4 (1) _(2i-l)7r _\ TT 3;r STT ITT

4 "JT'T'T'T

⁽²⁾

Khai trien eong thuc (1) ta nhan dugc:

sit) = A cos e^ cosilnfj) -Asm 0, sm(2;vfj) (3)

*£mait' nghiamosmipt@gmail com

liS2?Il?S*\/iaN.m 4(1) 1.2016 24

Do do CO the bieu dien tin hieu dieu che QPSK 6 dang khac:

s{t) = -4= I(t) cos(2;r/J) - ~ Q(t) sin(2;r/J) (4) V2 yjl Trong do:

lit) = yl2cosei,i=],2,3j (5)

Q{t) = yf2sm&^,i =1,2,3,4 (6) Vai 4 gia tri co the nhan ciia goc pha 9, ta thay cac

thanh ph§n I (In-phase component) va Q (Quadrature- phase component) chi co the nhan 1 trong2giatri {+1, -1}. Cac thanh phSn I va Q nay Hen he true tiep vai chudi bit dii heu dua vao dieu ehe voi ehom sao nhu mo ta tren hinh 1.

(01) •

(00) •

iT,T,-;T],Tri.

+1 I . • ' T

• (10) 3

s(t)--

\l.\t\<-

w

⁽⁷⁾

ts(t)

-T/2 0 T/2

Hinh 2 xungni

S(/l!))= j !(()«"'"*= I f ' " * - (8)

Hinh I. mdu lin hieu vd chdm sao diiu chi QPSK

5i©

Ky thuat ddo tdn ten so

Sau qua trinh xii ly bang goc, cac miu dii Heu la tin hieu xung co chu ky lay mau T voi bien do dugc lugng tu. Chiing ta xet mgt xung tin hieu (hinh 2) lam dai dien cho cac mau tin hieu voi bien do chiing ta chuan hoa la 1:

'L

~' 2 T_

" 2

Hinh 3 • dgc tnmg bien do pho xung mdu tin hieu

De thay dac tnmg pho, ta thuc hien phep bien doi Furier cho tin hieu nay:

-j/ \-Tll' io)TI2) Dac trung bien do pho cua cac mau tin hieu c6 dang sin(x)/x. Nhu vay, cac miu tin hieu co ph6 rat rong nen khong phu hgp trong cac kenh truyen. Dong thai, chiing se gay nhilu giua cac symbol (nhieu ISI - Intersymbol interference) do cac hai phu. Vi th6, tin hieu sau khi xii ly bang goc can phai dugc ban che bang thong, dong thoi giam nhieu ISI va ngi suy de ma rgng dai thong cho diSu chi vao song mang IF (Intermediate frequency) hoae RF (Radio frequency). Do do, cau true t6ng quat bg DUC bao gom to hgp kenh Ipc noi suy va bp tao dao dpng DDS (Direct digital synthesizer) [3-5].

(EHp*3r.,

Hinh 4 kien Iriic chung cua bo DUC

Kenh loc noi suy:

Bp loc so CO dap ling xung hiiu han FIR (Finite Impulse Response) tong quat la mpt he thong so dugc mo ta boi phuong trinh sai phan hoae duoi dang dap ling xung:

N-]

y(n)= Y,Wi^x{n-k) (9) k^o

y(n)='Zx(k)h{n-k) = x{n)*h{n) (10)

Hinh 5' mold bd toe so theo ddp dng xung

ferS^SiViaL^'^)^

²⁵

i = 0

(11)

S{n)-- l,n = 0 0,nitO

Thong qua phep bien d6i Z va Fourier phuang trinh (10), ( U ) chung ta nhan dugc:

y{z) = X(z).H(z) (13)

X(z) 6.

⁽¹⁴⁾

Hinh 6 cdu true chung ciia fip loc FIR bdc 4

X(!B) t.o

(15)

1

«(/)=

W HIT

--nt4

⁽¹⁸⁾

BW = Wi\ + P) = (19)

BiSn d6i Fourier nguoc (17), chung ta nhjn dugc (12) dap ling xung ciia bo loc RC.

D8 han ch8 dai thong tin hieu trong kenh truyen va giam nhilu ISI nguoi ta sir dung bp lpe RC (Raised- cosine filter). Bp Ipc nay dugc xay dung theo tieu chuan Nyquist vol dap ung xung dang cosine nang (raised cosine pulses) de xap xi dac tuyen dang sin(x)/x [4, 6]. Bang thong Nyquist JFdugc dinh nghia:

(16)

^-iK^P<i/i^^<-'

Dac trung bien dp - tan so H(f) cua bg Igc RC phu thupc vao 2 thara so la T (chu ky lay mau cua tin hieu) va p (he so lam phang). Trong do, p xac dinh khoang A/vuprt qua bang thong ciia bg loc {BW) so vai dai thong chiem giii Nyquist voi he so p nam trong dai tii Oden 1.

MO

s i n ( ; r f / r ) cosj^^t/T) (mIT) 1-

JI l!

1 /

"'

{2ptlTf

' \

— 9-0

— 9=0.25

— 9=0.5

— /i-1

'

(20)

Hinh 7: ddc tuyen bien do - tdn so ciia bo Ipc RC

Hinh 9 ddp img xung ciia bo IQC RRC (Root-raised-cosme filter)

Dap ling xung cho thay 2 thanh phan; thanh phSn dau tien c6 dang sin(x)/x de dam bao r§ng bO Igc c6 cac cue khong tai nhimg thai diem bpi lan chu ky lay mSu (hinh 7). Nhu vay, co th6 de dang trich miu diong tin theo thai gian; thanh phan thii hai la ham cosine de hieu chinh cho thanh phin thii nhat lam cho no co dac tuygn tin s6 tdt hon. Khi p dugc chpn cang nho thi dac tuy6n bien dp - tin s6 ciia bg loc cing tien dSn hinh vuong, con dap iing xung tra n8n dao dpng manh ban.

ie!«.12«..\fakL 4,1,1.20,6

²⁶

nghTa la keo dai ban.

Trong he th6ng thong tin thuc te co sir dyng cac bp Igc phoi hgp do anh Huong cua tap trang. Do do, de thoa man viec lam giam thieu anh Huong ciia nhieu ISI, dap ling xung pHoi hgp ciia 2 bg Ipc nay (1 bg a phia phat H.j,(f) va I bg a phia thu Hj^(f)) thoa man dap ling ciia bg loc RC, nghia la:

^ a c ( 2 ) = I M « ) 2 " " = ^-^ = H,iz).H,(z) (26) Trong do:

HiW = - 1 Hr(.f}.H„(f) = H{f) (21)

I - z "

H,(z) = \-z-

(27) (28) De thoa man dieu kien phoi hgp, dap ung ciia hai bg

lpe nay la giong nhau:

(22)

\r{Af)\-\H,(f)\ = ,l\H(fj\

Nhu vay, bg Igc RC co thg tach thanh 2 bo loc co dac trung bien dp - tan so giong nhau va bing can bae hai cua bp loc nay. Bg Igc co dap iing bien dp - tan s6 nhu vay dugc gpi la bg Igc RRC (23), (24).

HacU)'

-K^f^<w^^<-'

H|(Z) CO dac tnmg ciia mpt bp tich phan, trong khi H2(Z) CO dac tnmg dang rang luge. Nhu vay, de thuc hien Igc thong thap va npi suy, cau tnie cua bp loc CIC thuc hien truac tien bang cac bp loc rang luge, sau do chen cac miu khong va cuoi cung thuc Hien lay tich phan dS ngi suy dii lieu (hinh 11). Tii do, ta co cau tnie ciia CIC ngi suy nhu hinh 12 khi sii dung nhieu khau tich phan va rang luge ket Hgp.

x[nU

I I 1 . I i

».|/1 ,M

^{tttjf^}

*«(')=

I im(it(i-^)/r)t(4;ii;r)co5(ii(ita"') f _r

3zams I

TUl^ ^

Hinh 11 qua trinh ndi suy cua CIC comb sednns Integrator sections

* {«IT)[HVITf] ' 1"V] _ § _ ^ - - 0 - 0 r-H

A = 1 sample delay

A®-kl--kl-kl-k^

Hinh 12. cdu true bo loc CIC ngi suy lor CofTb <CIC> Pflef (LSAQth - 10, Oiil0T>>

Hinh 10: cdu triic chung cua Icenh iQcnQisuy

Bp Ipc CO kha nang ngi suy toe dp lay mau lan nhat dugc sii dung trong cac he thong vo tuyen la bg loc CIC (25-28). Bp Igc CIC co uu diem la clu tnie dan gian va toe do hoat dpng nhanh nen thich hgp cho vice xu ly tin hieu da toe do trong He thong v6 tuyen cau hinh mem [7].

ri,0<n<R-I

^^'-^"^ = |o,«^[0,R-l] ⁽²⁵⁾ Hinh 13, ddc luyin bien da -

KIKMHOC

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- -

DUC a c CompensaKm n u r (CFBl

. '- -...^^ • • 1 CFIIl(de»lgnKl> 1

\ r'l iilGhiffl

1 1 1 ; ; i i l 111 Iff lil \i \il \l

Hinh 14' dac tuyen hien do - tan

1 HB (detignM) I • \ • 1 — HB (quanUMll) 1 J S J_ J

;--r":'L:-Lj:Tlii

Hinh 15. ddc tuyin bien dd - tdn so cua HB (Half band low pass filler)

Bp Ipc CIC CO dp doc Ion trong dai thong (hinh 13), do toe dp ngi suy lan nen chiing ta su dung bp Ipc CFIR CO dac tuyen nang len de bii lai dp doc cua CIC (hinh 14). Bp loc CFIR npi suy thap nen lam viec vai toe dp lay mau thip. Do vay, CFIR diing truoc bg loc CIC trong he thong.

De giam anh Huong do viec ngi suy lan ciia bp Ipc CIC, nguoi ta co the ket hgp them cac bg Igc HB neu can thiet. Nhung bp Ipc HB nay duac thiet ke theo cau tnie FIR [8, 9]. Dac tuyen bien dp - tan so ciia HB can bang phiing trong dai thong de khong lam meo tin hieu (hinh 15).

Bo to hap tdn so DDS (Direct digital synthesizer):

Bp DDS thuc Hien tao tan so dieu che tin hieu len dai IF hoae RF cho bg DUC. Mo hinh thuc hien cua DDS (hinh 16) dua tren bp VCO (Voltage controlled oscillators) do Hang Xilinx de xuat [8].

Tin hieu tu dlu ra cua DDS dugc dgc tu bang tra luu tru gia tri cac mau ciia sine va cosine frong bg nha ROM nhu dugc th6 hien tren hinh 17.

Sau kenh Igc ngi suy, tin Hieu gom 2 thanh phan I va Q se dugc diSu ch6 IF hoae RF. Chung ta ky hieu chung tan s6 tao bai bg DDS uj^ cho ca hai trucmg Hgp dlu ra bp DUC la IF hoae RF.

^dds ( 0 = cos((y,0 + j sin(ftj,0 (29) Tin hieu tren kenh I va Q sau dieu che dao tan len:

x , ( 0 = I(t)cos((y,0 (30) XQ{t) = Q{\)sm{o>,t) (31) Tin hieu phat di la tong cua hai thanh phan tir hai

kenh 1 va Q ciia bg DUC:

x{t) = /(t) cos((u,0 + Q{t) sxnico^t) (^2) Ky thuat ddo tdn xuong so

Bp DDC thuc hien chpn ra dai tan quan tam de chuyen ve dai bang tin ca sa va giam tin so lay mau phii hpp voi bang tan nay.

mach RF trong he thong SDR

Iff"

^{HOC 28}

Kien tnie ehung ciia He thong vo tuy6n cau hinh m6m theo Rodger H. Hoskmg [9] (hinh 18) thuang bao gom phan RF; trong do, khfii RF thuc hien chuy8n tin hieu dai RF thu duge tu anten v8 dai IF. Sau do, bp ADC thuc Hien lay mau tin hieu rfii dua vao xu ly trong DDC. Trong truang Hgp dai tin hieu RF khfing qua Ion de CO the thuc hien bg thu hoan toan sfi, thi he thfing khong su dung them mach RF nay [10],

- : - 7 i » i

1 Digital Don-

; \ "1 ' '

; ""1

I B | . - ^-""^^

• • recovery

1 „„[

• » " ' • « '

r"

,r'"

"•

iW-

symbol

-Qln]

c bo DDC tren FPGA

" | :

cos(27r/,/+ ((>,)

iijumjmll

Hinh 20: cau true bd Castas loops

Ky thudt khoi phuc song mang:

Bg Costas loops khoi phuc song mang ca v6 tan sfi va pha tu tin Hieu thu dugc co dieu che de dfing bg a thiet bi thu. Chiing ta gia thiet tin hieu o dau vao bp DDC CO tan so thuc te / , dugc mo ta bang phuang trinh toan hoc:

r(t) = A(t) cos{2?r fit + (p^) (33) Gia thilt, tan so thiet lap ban dau cho bg VCO la / , . DIU ra bp nhan tin hieu trong Costas loops nhan dugc hai thanh phin tan s6 tfing va Hieu cua / , va / , :

r(fM2;r/,f+?j)=^[ci)s(2sOi+/,}!+(t,+Pj))+cos(2;r(^-/j)t+(f^-pj))] (34)

Bp lpe phfii hop khi do loai bo thanh phin tan so tong \k thuc hien lay mau lai theo toe dp cua symbol.

Tin hieu dau ra bp lpe phoi hgp nhan dugc:

/ ( 0 = ^ c o s ( 2 ; r { / i -/2)t+(«>, -<p.,)) Q(t) _A(t)

srn(2s-(/;-/2)t+(«>,-fP2)) Chiing ta dat:

A/(() = / ; - / 2 . A ^ ( 0 = A/(0 + « - Thay vao (36) va (37) nhan dugc:

/ ( 0 - ^ c o s ( A ? i ( 0 ) e ( 0 = ^ s i n ( A ^ ( 0 )

(36) (37)

(38) (39) Dau vao ciia bp Ipc loop filter la tich ciia 2 tin hieu tren 2 kenh I va Q:

^(Ofi(0=^cos(A^(0).sin(A(*(0) = —siii(2Aj#(0) (40) Bp Igc loop filter thue Hien loai bo tit ca nhilu tap tac dgng den thanh phin bien dp tai phia thu. DIU ra bg Igc nay chung ta nhan dugc tin hieu:

e{t) = -A\t)sm(2^m) (41) Voi dieu che QPSK, sau khi loai bo nhieu tac dpng den bien dp thi A(t) = ± 1 nen dau ra cua loop filter mang thong tin ve dp lech pha va tin s6. Tin hieu nay sir dung de hieu chinh VCO dua sai lech nay ve 0. Do do, song mang dugc khoi phiic

Kenh loc gidm mdu:

Bg Igc CIC co kha nang giam tfic do lay mau cao nhat nen dugc sir dung trong bg DDC lam bg Igc dau tien trong kenh Igc giam miu.

i A

[iiiiii miiii limit

f f f

Hinh 21 qud irinh thirc hien gidm mdu cua CIC Declmottng CIC filter

Hinh 22- cdu true cua hd loc CIC gidm m

leemGNGHEVietNam

4(1) 1.2016 29

Hinh 21. tuang quan ddp img ciia CIC n^i suy va gidm mau

Tit s\r tuong quan giira CIC npi suy va giam mau (hinh 23) ta th4y, dac tuyto H(2) cua chiing la tuong dong nhu thi hien tren hinh 13. Nhu vay, sau bp loc CIC trong DDC cin su dung them bo loc bii CFIR, cac khau loc tuy chpn HB &k giam toe dp lay mau va bg Ipc RRC lam bp Ipc phoi hgp lay mau vai toe do ciia symbol dl d3ng bg. CSu trie ciia DDC thS hien nhu tren hinh 24 [11-14].

k^-k®-k®--k® ^-X®-

eiia kenh I sau giai di6u ehS trong bfi thu dugc the hien tren may Hien song (hinh 32). Tin hieu dugc khoi phuc hoan toan trong bfi thu, tfic do lly mau 1,25 MHz.

- Tai nguygn FPGA su dung cho bfi DUC va DDC (khong tinh d6n tai nguyen tao tap trIng cho mo hinh kenh phat) la rat nho doi voi chip Kintex-7 XC7K325T va phu hgp cho cac chip FPGA tai nguyen nho han, chip FPGA the he cu.

Hinh 24 kenh Igc gidm mdu trong DDC

Dac tuyen bien dp - tan so va dap iing xung ciia cac bg Igc nay tucmg tu nhu trong DUC tren cac hinh 9,

1 4 v a l 5 . Ke't qua thir nghiem

Thiet ke (hinh 25) dugc thu nghiem voi cac tham so lua chgn sau; tfic dfi lly mau cac symbol tren hai kenh I/Q: 1,25 MHz; tan sfi IF: 25 MHz; tfic dp npi suy va giam mau: 80; mfi Hinh kenh truySn: sir dung tap trang phat tu trong FPGA; cac bo mach sii dung de thu nghiem: NetFPGA-IG-CMLvaAD9739AFMC Card.

K8t qua thii nghiem dupe the hien tren cac hinh tu 26 d6n 32. Tai nguyen chip FPGA su dung khi khong sii dung tap trang de mfi hinh kenh va co su dung tap trIng the hien tuang ung trong bang 1 va bang 2.

- Ket qua mo phong (hinh 28) va do tren may phan tich pho (hinh 31) cho thay, tin Hieu phat a dai IF CO bang thong 2,5 MHz (bang 2 lan bang thong cua symbol tren hai kenh I/Q o dai co so).

- Ket qua phan tich chom sao tin Hieu a phia thu (hinh 29) cho thay, chom sao sau bfi Ipc CIC khfing tap trung do nhilu tap trIng tii kenh truygn. Bg Igc phfii Hgp RRC da Igc nhieu ISI va nhilu tap nen chom sao tin Hieu dugc tap trung.

- Sau giai dilu che QPSK, tin hieu dugc khoi phuc (hinh 30).

- Chuoi bit kenh I ciia ban tin goc tii' phia phat va

Hinh 26 tin hi$u ct hang tan

te^'u

1

ca so sau kenh Ipc

i 1 > 1%'--!. o ® if jri -iQi nii^i • a "

"'"

^iU\

1—°^"Z\

i i i ^ i ^ i i i ^ - ^ - — ^ - -

F™qu™»(Hl)

*.!>

^w'

—

Hinh27 pho tin hi^u DDS trong DUC B F ™ . , ™ , D o ™ n .

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0.5

ifurmUulmon ^ ^ ^ Ji 1

^ •% -o ® e <«: • a [3 ^

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• a

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— H ^ U W M S ,

4 4 J 5

f -

Hinh28 phd tin hieu IF a phia phdt

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giai phap toi uu tai nguyen va toe dp cho phep thuc Hien He thfing hoan toan so trong mpt chip FPGA, dac biet la mo hinh thiet ke co the phu hgp va tiiy bien linh hoat cho mgi he thfing vo tuyen dua tren software defined radio.

MilTllLRJinMUIlJi^^

IfJIBlMlM

Hinh 30 bdn tm goc dphia phdi vd ddu ra sau giat dieu che QPSK apliia thu

Hinh 31. phS tin hiiu IF sau DUC

Hinh 32: ban tin goc vc Bdng 1 • tai nguyen FPGA su dung

khi khong diing kenh tap trdng

tdi nguyen FPGA sir dung 6 dung kenh t(ip trdng Logic

lltmadon Slice Registers Slice LUTs RAM/FIFO DSP4SE15 M M Frequency

Used 9371 9254 5 139

.\vaDable 107.600 203,800 445 840

2%

1%

16^1 M3 531MHz

UOnatiaii Slice Registers SLce LUTs RAMTIPO DSP48E1S M M . Frequency

Usrd 3056 2356 t 42 5179

. M ^ b k 407,600 203,800 445 840 i%

4MHi

Ket luan

Nghien ciiu da thiet ke va thii nghiem eac khfii dao tan len va xufing k6t Hgp ky thuat dilu chi QPSK tren CO so eong nghe vfi tuyin c4u Hmh mem. Thilt k l voi

Tai lieu tham khao

[I] Zhuan Ye, Grosspietsch J, Metnik G (2007), An FPGA Based All-Digilal Transmitter with Radio Frequency Output for Software Defined Radio. IEEE Design, Automation & Test m Europe Confer- ence & Exhibition.

[2] Rodger H Hosking (2008), Software Defined Radio Hand- book' Seventh Edition, Pentek, Inc.

[3] Kazaz T, Kulin M, Hadzialic M (2013), Design and imple- mentation of SDR based QPSK modulator on FPGA, IEEE Informa- tion & Communication Technology Electronics & Microelectronics (MIPRO).

[4] Kodah R.K. Bopppana L, Kondapalli S.R (2013), DDC and DUC filters in SDR platforms. IEEE Advanced Computing Technol- ogies (ICACT),

[5] Xilinx (2014), DUC/DDC Compiler V3.0, LogiCORE IP Product Guide.

[6] Ewa Hermanowicz, Miroslaw Rojewski (2014), "Square Root Raised Cosine Fractionally Delaying Nyquist Filter - Design and Per- formance Evaluation", JET InlernationalJournal of Electronics and Telecommunications, 60(3), pp.247-252,

[7] V Elamaran, R Vaishnavi, A Maxel Rozario, Slitta Maria Jo- seph, Aylwm Cherian (2013), CIC for decimation and mterpolation usingXilinx system generator. IEEE Communications and Signal Pro- cessing (ICCSC).

[8] Xiao Liangfen Liu Yi (2011), "Implementation of distnbuted FIR digital filter on FPGA", Electronic Measurement & Instruments (ICEMI), Vol 3.

[9] Xihnx (2011), DS795 LogiCORE IP FIR Compiler v63- Product Specification.

[10] Xilinx (2015), DDS Compiler v6 0, LogiCORE IP Product Guide.

[II] Hua-Mmg Liu, Guang-Jun Li, Bo Yan, Qiang Li (2010), A lOOMHz Digital Down Converter with modified FIR filter for wide- band software-defined radios. IEEE Electronics and Information En- gineenng (ICEIE), 2010 International Conference, 1-3 Aug, 2010.

[12] Wu Changrui, Kong Chao, Xie Shigen, Cai Huizhi (2010).

Design and FPGA Implementation of Flexible and Efficiency Digital Down Converter. Signal Processing (ICSP),

[13] TrSn Van NghTa (2010), Nghien cim. thiit ke mdy thu thi he so software defined radio tren eong ngh? FPGA, Tuyfin tap bdo cao khoa hoc Hgi nghi Do luong toan quoc lan thii 5.

[14] Nguyen Thi Hifiu, Trin Xuan Kien, TrJin Van Nghia (2010).

"Nghien ciru, thiet kfi bo chuyfin dich tin hifiu vfi dai co sa trfin nfin eong nghfi FPGA". Tgp chi Nghien cieu KH&CN qudn su, thang 10

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