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3DEffectOptions
3DEffectOptions
Byimplementinga3Deffectinthisoptionbox,thePCM3793Aisenabledtoprovide3Dsoundtothe
headphoneandspeakeroutputswithlowpowerconsumptionduringeitherADCorDACoperation.Check
the3Deffect,thenselectanEffecttypeandanEfficiencydrop-downmenutoobtainthedesired3D
enhancement.
Effecttypemeanstheselectionofaband-passfilter(BPF);theBPFfiltersthesound,andenablesahigh
percentageofheavy3Denhancementstobeappliedtothesignal.
Effecttypeandefficiencyarecontrolledthroughtheuseofcheckboxes.
NotchFilter1Coefficient,NotchFilter2CoefficientOptions
Insomeapplications,incomingnoisesuchasmotorcontrolnoise,CCDnoiseandothermechanicalnoise
maynotbenegligible.ThePCM3793Aprovidesaveryusefulfunctiontoreducesuchinterferencewiththe
notchfilterfunction.
WhenthecheckboxofNotchFilter1CoefficientorNotchFilter2Coefficientischecked,coefficienta
1
and
a
2
ofthenotchfiltercanbeprogrammedateacheditbox.
Loadthevaluesoff
c
,f
b
andf
S
intotheFilterCalculatorgroupbox.
ClickApplytoFilter1orApplytoFilter2.Thecalculatedcoefficientwillthenappearinthea
1
anda
2
edit
box.
Finally,clicktheUpdatebuttonforeachNotchfiltercoefficient.Tocompletethenotchfilteroperation,the
Updatebuttonmustbeclicked.
NotethatUpdatestepisrequiredeachtimenewordifferentparametersareloadedtothedialogbox.
Followthesestepstoupdatethenotchfiltercoefficient:
Step1.ClickthecheckboxofNotchFilter1CoefficientorNotchFilter2Coefficient.
Step2.Inputtheparametervaluesf
c
,f
b
andf
S
.
Step3.ClickApplytoFilter1orApplytoFilter2.
Step4.Updateforeachnotchfiltercoefficient.
Eachcoefficientiscalculatedusingthefollowingequations.
a
1
=–(1+a
2
)cos(ω
o
)
a
2
=[1–tan(ω
b
/2)]/[1+tan(ω
b
/2)]
where:
•f
S
=samplingfrequency
•f
c
=centerfrequency
•f
b
=bandwidth
•ω
o
=2πf
c
/f
S
representstheangularcenterfrequency
•ω
b
=2πf
b
/f
S
istheparametertoadjustbandwidth
HereareseveralexamplecoefficientcalculationsusingEquation3-1andEquation3-2.These
measurementsarealsoshowninFigure3-16.
Given:f
S
=16kHz,f
c
=0.5kHz,f
b
=0.2kHz
a
2
=0.924390492(converteddecimaltohex:3B29h)
a
1
=–1.887413868(converteddecimaltohex:8735h)
a
2
:F[215:208]=3Bh,F[207:200]=29h
a
1
:F[115:108]=87h,F[107:100]=35h
32Set-UpGuideSBAU127–July2007
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