AT Command Manual for Sierra MC87XX Module

MC87xx Extended AT Command Reference
88 2130616
Theembeddedmodulecanserveasanintegralcomponentofa
morecomplexaudiosystem,suchasaPDAwithaseparate
codecinterfacingwiththemainprocessor.Inthiscase,the
interfacebetweenthemodemandPDAcodeccanbeassimple
asline‐levelaudiowithnotransducerconsiderations.
Phone‐
orientedfunctionssuchasechocancellationandFIRfiltering
aretypicallylefttothemodule,whilepath‐switchingand
transducerinterfacesaretheresponsibilityofthePDAcodec.
Functionssuchasadjustablegainandvolumesettings,DTMF
andringertonegeneration,andmixingcanbeaccomplishedin
eithercodec,
dependingonthearchitectureoftheparticular
product.Theinterfacebetweenthemoduleandhostaudio
systemsisusuallytheprimaryaudiointerfacesettoline‐level
amplitudes,routedasdifferentialpairsfornoiseimmunity.
Figure 7-1: Audio block diagram
Audio profiles
TheATcommandsetallowsyoutohavedifferentaudio
configurationsfordifferentpurposes.Asanexample,assume
youareembeddingthemoduleinadevicethathasahandset
modeandaspeakerphonemode.Assumealsothatyouwant
tousedifferenttransmitgain,noisesuppression,and echo
cancellationsettings
ineachmode.Youcanstorethesettings
foreachmodeinseparateaudioprofiles,thenactivatethe
appropriateprofileasyourapplicationswitchestohandsetor
speakerphonemode.