第
48
卷
第
5
期
2012
年
9
月
南京大学学报
(
自然科学
)
JOURNALOFNANJING UNIVERSITY
(
NATURALSCIENCES
)
Vol.48
,
No.5
Se
p
t.
,
2012
Contributionstothe9
th
InternationalS
y
m
p
osiumon ModernAcoustics
(
I
)
Acarrierfre
q
uenc
y
andbasebandwaveformestimationmethodfor
underwateracousticbinar
yp
haseshiftke
y
in
g
si
g
nal
Wan
g
XiaoYan
,
Fan
g
ShiLian
g
,
YaoShuai
(
Ke
y
Laborator
y
ofUnderwaterAcousticSi
g
nalProcessin
g
ofMinistr
y
ofEducation
,
SoutheastUniversit
y
,
Nan
j
in
g
,
210096
,
China
)
Abstract
:
Intheareaoftheunderwateracousticscommunicationand detection
,
the modulationof
binar
yp
haseshiftke
y
in
g
(
BPSK
)
isoneofthecommonl
y
usedmodulationmode.Asaresult
,
thenon
coo
p
erativeinterce
p
t
p
rocessin
g
ofBPSK si
g
nalisanim
p
ortantresearch.Thecarrierfre
q
uenc
y
and
basebandwaveformarethecriticalinformationofBPSKsi
g
nalinterce
p
t
p
rocessin
g
.Automaticextraction
al
g
orithmsofthese
p
arametersinthenoncoo
p
erationconditionareneededtobeachieved withoutan
y
p
rioriinformation.Intheviewofthis
p
roblem
,
this
p
a
p
er
p
resentsacarrierfre
q
uenc
y
estimationmethod
basedon
p
resu
pp
osedfre
q
uenc
y
searchandabasebandsi
g
nalwaveform estimation methodusin
g
the
carrierfre
q
uenc
y
information Boththeestimation methodsofthe si
g
nalcarrierfre
q
uenc
y
and the
basebandwaveformusethedownconversion
p
rocessin
g
.Thecarrierfre
q
uenc
y
estimationmethodbased
on
p
resu
pp
osedfre
q
uenc
y
searchisachievedb
y
usin
g
thechan
g
esincharacteristicsofthedownconverted
si
g
nalwithdifferent
p
resu
pp
osedfre
q
uenc
y
.Thisestimationmethodisofhi
g
haccurac
y
andhasa
g
ood
p
erformanceatlowsi
g
naltonoiseratio.Afterthecarrierfre
q
uenc
y
estimation
,
j
ud
g
in
g
the
p
ositiveand
ne
g
ativeinterchan
g
eofthedownconversionsi
g
nalcanrecoverthebasebandwaveform.Forthedown
conversion
p
rocessin
g
,
theinitial
p
haseandthearrivaltimeofthereceivedsi
g
nalcanbrin
g
adverse
effects
:
thesi
g
naltonoiseratereducesandthesi
g
naleventendstozero.Andtheestimationofthetwo
p
arametersisver
y
difficultundernoncoo
p
erationcondition.In ordertoensurethestabilit
y
ofthe
estimationmethods
,
we
p
utforwardtwoa
pp
roaches
:
oneistoselectthelar
g
estam
p
litudeofthedown
conversionsi
g
nalbothfrom therealandima
g
inar
yp
arts
;
anotherisbasedonthe
p
haseestimation.
Althou
g
hthesea
pp
roachesare
p
ossibletolowertheout
p
utsi
g
naltonoiseratio
,
thedeclineran
g
eis
limited.The
y
reducetheadverseeffectsofunknown
p
arametersand wecom
p
aretheir
p
erformance
throu
g
htheoreticalanal
y
sisand simulationtests.In orderto verif
y
thecorrectness ofthecarrier
fre
q
uenc
y
andthebaseband waveform estimation methods
,
weuse MonteCarlocom
p
utersimulation
a
pp
roachtotest.Thesimulationtestsresultsshowthatthecarrierfre
q
uenc
y
estimation methodhasa
better
p
erformancethanthes
q
uarelaw methodandthe
p
owers
p
ectrum centroid method.Andthe
a
pp
roachbasedonthelar
g
estam
p
litudeselectin
g
out
p
erformsthea
pp
roachbasedonthe
p
haseestimation
forbasebandwaveformestimationwhenthereexiststheinitial
p
hase.Atthesi
g
naltonoiseratioof5dB
,
FoundationItems
:
NationalNaturalScienceFoundationofChina
(
11104029
,
61101164
)
ReceivedDate
:
2012-06-18
Corres
p
ondin
g
Author
,
Email
:
x
y
anwseu
@
g
mail.com