Introductiontothesystem
Thesesystemsoftenrequirethecomputertoprocessandrespondappropriatelytothecollectedmulti-channelinformationwithinseconds,milliseconds,orevenmicroseconds.Thereal-timeprocessingsystemisoftenahighlycoupleddistributedprocessingsystemcomposedofmultiplecomputers.
Systemfeatures
Oneofthecharacteristicsofreal-timesystemsisthatthesystemoftenhasvarioussensorsandmultipledigital-to-analogconversionfacilities,thatis,theoutputdataofreal-timesystemsissometimesoutputfromsensorsAnalogquantity,soitisnecessarytoconvertittodigitalquantity(calledA/Dconversion)beforeitcanbeprocessedbycomputer;ontheotherhand,computerprocessingresult(digitalquantity)sometimesneedstobeconvertedintoanalogquantity(calledD/Aconversion)Theoutputcontrolstheactionmechanism.Thesecondfeatureofareal-timesystemistoachievehighreliabilityunderthepremiseofensuringthenecessarycomputingspeed(note:sometimesextremelyhighspeedisrequired).Dual-systemhotbackuporfault-tolerantcomputersarecommonlyusedsolutions.Anotherfeatureofreal-timesystemsisenvironmentaladaptability.Thesystemisoftenusedinindustrialfieldenvironments,oreveninmoresevereenvironments.Theformerrequiresthecalculationtoworkinawiderangeoftemperatureorhumidity,andcanadapttotheelectromagneticinterferenceenvironmentoftheindustrialsite;thelatteroftenreferstothefieldorvehicle,shipborne,airborne,spaceborneandotherapplicationenvironments,soitoftenrequiresspecialWideoperatingtemperaturerange(suchasminus40degreesCelsiusto85degreesCelsius),moisture-proof,shock-proof,anti-shock,anti-saltsprayandanti-mildew,etc.,allrequirethecomputertoadoptspecialcomponentsandspecialstructures.Thisrequirementiscalled""Reinforcement"requirements.Anotherfeatureofreal-timesystemsisthattheyhavehighrequirementsforsoftwarereliability.Forexample,inmilitaryandaerospaceapplications,specificprogramminglanguages(suchasAdalanguage)andhigh-qualitycompilersareoftenusedtoensurethattheprogramsaregood.Itispossibletomakefulluseofthehardwarecharacteristicstomakethetargetprogramhaveahighqualityintermsofrunningspeed.Inaddition,manyreal-timeapplicationsinvolvealargenumberofcommunicationlinks,especiallywirelesscommunication.Inadditiontorequiringhigh-sensitivityreceivingfacilities,itisalsoimportanttouseredundantcodestoensurehighreliabilityofdatacommunicationundersevereweatherconditions.
