简介:C-2000前置放大器采用了Accuphase特有的AAVA(AccuphaseAnalogVari—gainAmplifier,金嗓子模拟可变增益放大器)音量控制设计,其音量控制的步级数可达216级,即65536级之多,可以实现非常精确的调节。此外,AAVA还能有效提高整机的信噪比并保持不变的频响特性。
简介:Alow-lossfiberopticrotaryjoint(FORJ)hasbeendesignedbyusingtwokindsofC-lenscollimators.Itsinsertionlossandinsertionlossvariationduetorotationwithsingle-modefibercollimatorislessthan1.76dBand0.43dBrespectively.Themaximuminsertionlossandcouplingvariationduetorotationwithmulti-modefibercollimatoris1.71dBand0.29dB,respectively.ThiskindofFORJfeatureslowinsertionloss,smallcouplingvariationduetorotationandlowcost.
简介:Thetracking,telemetryandcommand(TT&C)missionisextremelyreliableforitscharactersofsmalltimehorizonandhighredundancy.Thecombinedforcingandfailurebiasing(CFFB)methodthatisusuallyusedforsimulatingtheunreliabilityofthehighlydependablemissionsystemseemsnotsoefficientfortheTT&Cmission.TheconceptabouttheimportanceoffailuretransitionisproposedbasedonthelogicalrelationshipbetweenTT&Cmissionanditsinvolvedresources.Then,theimportanceisusedforreadjustingthetransitionrateofthefailuretransitionwhenusingtheforcingandfailurebiasingduringthesimulation.ExamplesshowthattheimprovedCFFBmethodcanevidentlyincreasetheoccurrenceoftheTT&Cmissionfailureeventanddecreasethesamplevariance.MoreredundancyoftheTT&CmissionleadstotheimprovedCFFBmethodmoreefficient.
简介:Modelingandreasoningondomaincontextsplayakeyroleforaddingintelligencetocommunicationservices,andtheapproachofcapability-basedrequirementengineeringensuresthescientificityandaccuracyofrequirementelicitation.Thispaperpresentsacapability-basedcontextontologymodelingapproachforcommandandcontrol,communication,computer,intelligence,surveillanceandreconnaissance(C4ISR)communication.Primarily,acapability-basedC~4ISRcommunicationmeta-conceptmodelandaC~4ISRcommunicationcontextmeta-ontologyareconstructed.ThecontextontologyisestablishedundertheconstraintsoftheC~4ISRcommunicationcontextmeta-ontology,andfurthermore,algorithmsareproposedtosupportcontextreasoningbasedondescriptionlogic.Acasestudyispresentedtodemonstrateapplicabilityoftheproposedmethod.
简介:说起NOKIA许多烧友都不陌生,它可是数字机行业的老前辈.我记得大概是七八年前,卫星信号大多还是模拟信号时,数字信号还是凤毛麟角,时常能见到卫星数字接收机的品牌少的可怜,也只有NOKIA,"现代"等少数产品.当时大家对卫星数字信号传送方式和工作原理还不是很了解,当时的卫星数字接收机,被称为"解码器"(呵呵,现在看来不过是一台免费的卫星数字接收机),当时只有欧洲国家驻华大使馆和一些高档酒店使用(只能接收亚洲2号卫星上面的欧洲五套节目),价格也较为昂贵.后来随着卫星数字信号技术的成熟,许多模拟节目数字化改造成功,市场上数字机的需求量不断扩大,各种品牌的数字机先后出台,特别是近两年,有线数字接收机(下面简称有线机顶盒)和开路数字接收机已开始大量使用.
简介:回想去年年来的手机市场,以索尼爱立信P908.摩托罗拉A768.多普达696等为主的智能手机着实火了一把,也让手机在功能方面进行了一次洗礼。那时候也有很多人认为智能手机会在今年大红大紫,成为当然的主流。然而.手机在功能方面虽然一直在发展.但却衍生出拍照手机商务手机.娱乐手机等不同的形态.在过去意义上的综合性能的智能手机新品却并不多见。作为摩托罗拉A768和索尼爱立信P908的升级作品,摩托罗拉A780和索尼爱立信P910c这两款智能手机终于在年底和人们见面了,同时出现在手机市场的选两款重量级作品到底有什么独到之处?这里就向大家一一进行展示。