ASPENArchitecture and Signal Flow

TECHNOLOGY OVERVIEW

Rio Rancho, NM, USAwww.lectrosonics.com

• OptimizedArchitectureTM

• AdvancedAcousticEchoCancellation

• ThirdOctaveNoiseReduction

• Fullcrosspointmatrixwith48outputsandunlimitedinputexpansion

• TCP/IPEthernetaddressable

• Simultaneousmulti-point3rdpartyandnativecontrol

• Patented,multi-modeautomaticmixingatthematrixcrosspoints*

• Ultra-lowlatency

• AutomaticMaster/Slavedetection

• SingleCAT6interconnectioncarriesdata,audioandcontrolsignalsbetweenunits

*US Patents 5,414,776 and 5,402,500

Hardware ArchitectureThe variety of models in this series are created by com-bining “building block” circuit board assemblies:

• 8input,12outputmixerboard

• 16channelinputonlyboard

• 8channelinputonlyboard

• Conferenceinterfaceboard

A single board can be enclosed by itself in a stand-alone 1RUchassis,orcombinedwithanotherboardina2RUchassistocreateavarietyofmodels.The2RUmodelsincludeanLCDwithcomprehensiveaccesstoallsystemsettings and activity.

812

1612

Mixerandinputonlyunitsincludethefollowingmodels:

• SPN812 8input,12outputmixer

• SPN1612 16input,12outputmixer

• SPN1624 16input,24outputmixer

• SPN2412 24input,12outputmixer

• SPN16i 16channelinputonly

• SPN32i 32channelinputonly

• SPNConference Conferenceinterface

• SPNTrio 8input,12outputmixer withConferenceinterface

• SPNDNT Dantenetworkprocessor*

Inputonlyunitsdeliveroutputstothedigitalbus,sotheyarealwaysusedwithamixerorconferenceboardtoprovidephysicalaudiooutputsforthesoundsystem.

TheSPNConferencemodelisusedwithamixertopro-videmic/lineaudioinputsandoutputs.

All data and audio from the Slave units in the system is gathered in the Master, so a single connection between acomputerandtheMasterallowssoftwareaccesstoallunits in the stack.

TheslightthroughputdelayofinputsfromslavesandthemasterintheASPENbusisautomaticallysynchronizedtomaintainabsolutesignalphaseatalloutputs.

AtthecoreofeachASPENboardisapowerfulcom-munications and control structure. A latest generation SHARC®processor*performsthemillionsofcalculationsrequiredtoimplementsignalprocessing,automixing,echocancellationandnoisereduction.AnFPGAwithagigabit transceiver coordinates the data flow in and out oftheASPENbus.ThemicrocontrollerinterfaceswiththeI/Oports,thefrontpanelLCD,therealtimeclockandoverseesthetemperatureregulation.

Stackingmultipleunitsissimplyamatterofconnect-ingthemasshownhere.EachboardassemblyhastwoRJ45connectors.Theupperjackoneachunitconnectstothelowerjackonthenextunitaboveit,andsoon.Theunitatthetopofthestackhasnoconnectiontotheupperjack,soitautomaticallybecomestheMasterinthe system. The lowermost unit has no connection to its lowerjack,soitautomaticallybecomesthelowermostslave.Theunitsarepresentedinthesoftwareinthesame manner they are interconnected with this cabling.

ASPEN PORT

*DanteTM is a trademark of Audinate Pty Ltd.SHARC® is a registered trademark of Analog Devices, Inc.

Signal Propagation in the ASPEN BusTheASPENbusprovidesa1GbpsthroughputcarryingaudioanddatawithasingleCAT6connectionbetweenthe units in a system.

Whenmultipleunitsarestacked,MasterandSlaveunitsare automatically detected and configured for the correct signal flow.

Audioanddatasignalspropagatethroughsubmixes. Thelowermostslaveinthesystemgeneratesasubmixofsignalsfromdevicesconnectedtoitandpassesthesubmixtothenextslaveaboveit.

Eachintermediateslaveunitaddstothesubmixfromtheunitbelowit,updatesthesubmixandpassesitontotheunitaboveit.Theprocesscontinuesthroughallslaveunits in the system with no limitation on the total number of slave units that can be used.

TheMasterunitgathersthesubmixfromtheslavebelowit,updatesitwithitsownsignalsandgeneratesthefinalmix.Thefinalmixisthenbackpropagatedtoallslaveunitsbelowittoenablesystemwideautomixingandcontrol.

Theaudiooutputofallunitsinthesystemistakenfromthe48channelfinalmix.

Thisuniquearchitectureallowsasinglecomputerornetwork connection to the Master to have access to all units in the stack.

Scalability in the ASPEN MatrixEach8x12mixerboardprovides8physicalinputs,12physicaloutputsandaccesstotheaudioanddatafromthe48finalmixesintheASPENbus.Fourvirtual inputs areprovidedinanysystemconfigurationtofeedsignalsfromabuilt-insignalgeneratorforsetup,diagnosticsandsound masking.

Asmultipleunitsarestacked,thesizeofthematrixgrowsaccordingly.Forexample,a16input2RUmixermodelactuallyhas20inputswhenthevirtualinputsareincluded.Thematrixthenconsistsof960fullyfunctionalcrosspoints(20x48).Asmoreinputsareadded,thesizeofthematrixcontinuestoincreasewithoutlimitation.

Evenwithhundredsofinputs,everyinputcanfeedanyoneorallofthe48outputs,withfullsignalprocessingavailableoneveryinputandoutput.

Optimized ArchitectureTM

The ideal structure for signal flow and functional blocks throughasystemwidematrixisadirectpathfrominputstocrosspointstooutputs,withnoextrapathsortapsnecessarytoaddsignalprocessing.Itmustofferafullcapabilityofroutingeveryaudioinputtoanyoneorallaudiooutputswithoutlimitation.Everyaudioinputshouldhaveitsowndedicatedsignalprocessingblockspresentatalltimes.Everyaudiooutputonanyunitinthesystemshouldhavefullaccesstoanycrosspointinthematrix,andhaveitsowndedicatedsignalprocessingpresentatalltimes.ThisidealstructureisfullyrealizedintheOptimizedArchitectureTM ofASPEN.

Allavailablesignalprocessingisenabledoneveryinputandoutputwithnoresourcemeteror“gasgauge.”Signalprocessingblocksareconfiguredintheoptimalsequence needed to ensure the highest signal to noise ratio and lowest distortion. This architecture eliminates the need to manually construct a drawing and connect oneprocessingblocktothenextoneinthechain.Simplyenableacrosspointandtheconnectionsaremade.

Setupisstraightforwardandsimpleinspiteoftheim-menseamountofprocessingavailable.Settingsareappliedinrealtimeasthesystemisoperatingwithouttheneedtocompileanddownloadfilestothehardware.Oncethesetupiscomplete,itissavedtoapresetinthehardwareandtoadiskfileforbackup.

InputProcessing

Inadditiontothedelay,filtersandcompressor,therearetwospecialpurposeprocessingblocks:

• NRF(noisereductionfilter)

• ADFE(autodigitalfeedbackeliminator)

NRFemploysaproprietarynoisereductionalgorithmoneveryinputchannelusinga1/3octaveanalysisanddownwardexpansion.Theamountofnoisereductionap-pliedtothesignalateachinputisadjustablefrom6dBto35dBasneededforthesignalconditionsandtosat-isfyindividualpreferences.Theprocessisveryeffective,withalmostnoaudibleartifactsat18dBormore.Highervaluesareavailableforextremelypoorconditionswherenoiseisextremelyhighandintelligibilityispreferredattheexpenseofsubtleartifactsintheaudio.

ADFE(autodigitalfeedbackeliminator)isanotchfilter-ingprocesswithstaticordynamicbehaviorasdefinedinthesetup.Fixednotchfilterscanbeconfiguredasneededforappropriateapplications,anddynamicnotchfilters can be defined to deal with changing conditions.

OutputProcessing

Eachoutputchannelcantakeitssignalfromthematrixor from an internal signal generator. The generator can deliveravarietyofsignaltypesforsetup,diagnosticsandsoundmasking.Theprocessingblocksoneveryout-putarearrangedintheoptimalsequenceusedtofeedpoweramplifiersandrecorders.

Low LatencyThethroughputlatencyofasinglemasterboardisonly1.33ms,regardlessofhowmuchprocessingisbeingused.EachadditionalPCBaddsonly0.125ms.

200inputscanbehandledwithonly4.33mslatency(1.33msforthemasterPCBplus24additionalPCBsat0.125mseach.

Otherexamplesinclude:

• 264inputswithonly5.33mstotallatency

• 328inputswithonly6.33mstotallatency

• 456inputswithonly8.33mstotallatency

• Unlimitedmaximumwith1msaddedforeachad-ditional64inputs(8boards)

Latencyisnotaffectedbytheamountofprocessingbe-ing used at any stage in the signal chain.

Everyinputisautomaticallysynchronizedtoeliminatephasedifferencesbetweentheinputsincludedinthefinalmixes.

Network Audio TransportTheSPNDNTprocessorinterfacestheASPENdigitalmatrixwiththeDantedigitalmatrixtotransportaudioviaagigabitethernet.EachASPENsysteminanetworkoperatesindependently,andsendsandreceivesaudiosignalstoandfromthenetwork,with32inputsand32outputs.StandardgigabitorAVBcompliantswitchescanbe used.

Inessence,theSPNDNTisafullfunctionDSPmixerandprocessorlikeotherASPENmodelsexceptthatinsteadofanalogI/Oports,itusesdigitalnetworkDanteports.Theon-boardAudinate®*BrooklynIImodulefunc-tionsasanativeDantedeviceusingstandardethernetorAVBcompliantswitches.

812 812

1612 1612

DNT DNT

Gigabit Ethernet

Dante Virtual SoundcardDante Enabled Audio Devices

Dante PCIe SoundcardOther Dante Devices

SPNDNT Processor SPNDNT Processor

ASPEN System ASPEN System

Primary Primary

SecondarySecondary

*US Patents 5,414,776 and 5,402,500

Seamless Automatic MixingLectrosonicspioneeredadaptiveproportionalgainauto-maticmixingalgorithms.Theproprietaryalgorithm*em-ployedinASPENisaseamlessprocessthateliminatesabruptswitching(gating),controlsacousticfeedbackandsuppressesbackgroundnoise.

Allactiveinputchannelsaresummed,andthenthelevelofeachchanneliscomparedtothetotalsum.Channelsare then attenuated so that the resulting sum is equal to onechannelatfulllevel(NOM=1)withtheloudestchan-nelstilltheloudestinthemix.Thealgorithmoperatesinthesamemannerthatahumanoperatorwouldinmixinga conference manually on a console. Unused mics are attenuatedandthoseinuseareemphasized.

Thisautomixingalgorithm,workinginconjunctionwiththeAECintheASPEN Conferenceprocessor,providesimpressiveechocancellationandnoisereduction.

The algorithm includes a unique automatic skewing processthatappliesasubtleprioritytothechannelthathasbeentheloudestforthelongestperiodoftime.Theskewingfurtherreducesinactivechannelsandpreventscomb filtering by never allowing two channels to be mixedatthesamelevel.

Theautomixingtakesplaceatthematrixcrosspoints,whichallowseachinputsignaltoexhibitadifferentbe-haviorateveryoutputinthesystem.Forexample,inputchannel4couldbeconfiguredforAutobehavior(normalautomixing)atoutput6forlocalsoundreinforcement,Directbehavior(noattenuation)atoutput10forrecord-ing, and so on. There are five different behaviors avail-able:

• Direct-noattenuation

• Auto-normalgainproportionalautomixing

• Phantom-specialmodeformix-minussystems

• Override-dominantinautomixingactivity

• Background-subordinateinautomixingactivity

The Phantommodeallowsthechanneltoparticipateintheautomixingalgorithmatanycrosspoint,butnotdelivertheactualaudiosignaltotheoutput.Thisisusedtocombinezonesforroom-wideautomixingactivityinamix-minusreinforcementsystem.Theautomixingactioniscommontoallzones,buttheaudiosignalroutingtotheloudspeakersremainsasisitconfiguredinthesetup.

*Audinate® is a registered trademark of Audinate Pty Ltd.

Single Point of ControlAllASPENmodelssupportsimultaneoususeofEther-net,RS232andUSBportsforsetup,monitoring,diag-nostics and control.

InstallersandoperatorscanusethesoftwareGUItomonitorthestateoftheprocessorviatheUSBporttoverifythatcommandssentfromthe3rdpartycontroller(overRS232)areworkingcorrectly.

Remotemonitoringandsetupcanbeconductedviaa network connection and from remote sites over the internet.

1624

Conference

16i

Ethernet RS-232

USB

15February2012

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