毕业设计外文文献翻译.docx
- 文档编号:2160711
- 上传时间:2022-10-27
- 格式:DOCX
- 页数:9
- 大小:23.25KB
毕业设计外文文献翻译.docx
《毕业设计外文文献翻译.docx》由会员分享,可在线阅读,更多相关《毕业设计外文文献翻译.docx(9页珍藏版)》请在冰豆网上搜索。
毕业设计外文文献翻译
毕业设计_外文文献翻译
本科毕业设计外文文献翻译(题目:
packethandlinghardwaresupport
学生姓名:
学院:
系别:
专业:
班级:
指导教师:
二〇一四年六月
packethandlinghardwaresupport
参考文献:
texasinstruments1101low-powersub-1ghzrftransceiver.ti.2013
the1101hasbuilt-inhardwaresupportforpacketorientedradioprotocols.intransmitmode,thepackethandlercanbeconfiguredtoaddthefollowingelementstothepacketstoredinthetxfifo:
aprogrammablenumberofpreamblebytes
atwobytesynchronization(sync)word.canbeduplicatedtogivea4-byte
syncword(remended).itisnotpossibletoonlyinsertpreambleoronlyinsertasyncword
acrcchecksumputedoverthedatafield.
theremendedsettingis4-bytepreambleand4-bytesyncword,exceptfor500kbauddataratewheretheremendedpreamblelengthis8bytes.inaddition,thefollowingcanbeimplementedonthedatafieldandtheoptional2-bytecrcchecksum:
whiteningofthedatawithapn9sequence
forwarderrorcorrection(fec)bytheuseofinterleavingandcodingofthe
data(convolutionalcoding)
inreceivemode,thepackethandlingsupportwillde-constructthedatapacketbyimplementingthefollowing(ifenabled):
preambledetection
syncworddetection
crcputationandcrccheck
onebyteaddresscheck
packetlengthcheck(lengthbytecheckedagainstaprogrammablemaximum
length)
de-whitening
de-interleavinganddecoding
optionally,twostatusbytes(seetable27andtable28)withrssivalue,linkqualityindication,andcrcstatuscanbeappendedintherxfifo.1.datawhitening
fromaradioperspective,theidealovertheairdataarerandomanddcfree.thisresultsinthesmoothestpowerdistributionovertheoupiedbandwidth.thisalsogivestheregulationloopsinthereceiveruniformoperationconditions(ondatadependencies).
realdataoftencontainlongsequencesofzerosandones.inthesecases,performancecanbeimprovedbywhiteningthedatabeforetransmitting,andde-whiteningthedatainthereceiver.
with1101,thiscanbedoneautomatically.bysettingpktctrlo.white_data=1,alldata,exceptthepreambleandthesyncwordwillbexor-edwitha9-bitpseudo-random(pn9)sequencebeforebeingtransmitted.thisisshowninfigure16.atthereceiverend,thedataarexor-edwiththesamepseudorandomsequence.inthisway,thewhiteningisreversed,andtheoriginaldataappearinthereceiver.thepn9sequenceisinitializedtoall1’s.2.packetformat
theformatofthedatapacketcanbeconfiguredandconsistsofthefollowingitems(seefigure17):
preamble
synchronizationword
optionallengthbyte
optionaladdressbyte
payload
optional2bytecrcthepreamblepatternisanalternatingsequenceofonesandzeros(10101010…).theminimumlengthofthepreambleisprogrammablethroughthevalueofmdmcfg1.num_preamble.whenenablingtx,themodulatorwillstarttransmittingthepreamble.whentheprogrammednumberofpreamblebyteshasbeen
transmitted,themodulatorwillsendthesyncwordandthendatafromthetxfifoifdataisavailable.ifthetxfifoisempty,themodulatorwillcontinuerosendpreamblebytesuntilthefirstbyteiswrittentothetxfifo.themodulatorwillthensendthesyncwordandthenthedatabytes.
thesynchronizationwordisatwo-bytevaluesetinthesync1andsync0registers.thesyncwordprovidesbytesynchronizationoftheiningpacket.aone-bytesyncwordcanbeemulatedbysettingtheaync1valuetothepreamblepattern.itisalsopossibletoemulatea32bitsyncwordbysettingmdmcfg2.sync_modeto3or7.thesyncwordwillthenberepeatedtwice.
1101supportsbothconstantpacketlengthprotocolsandvariablelengthprotocols.variableorfixedpacketlengthmodecanbeusedforpacketsupto255bytes.forlongerpackets,infinitepacketlengthmodemustbeused.
fixedpacketlengthmodeisselectedbysettingpktctrl0.length_config=0.thedesiredpacketlengthissetbythepktlenregister.thisvaluemustbedifferentfrom0.
invariablepacketlengthmode,pktctrl0.length_config=1,thepacketlengthisconfiguredbythefirstbyteafterthesyncword.thepacketlengthisdefinedasthepayloaddata,excludingthelengthbyteandoptionalcrc.thepktlenregisterisusedtosetthemaximumpacketlengthallowedinrx.anypacketreceivedwithalengthbytewithavaluegreaterthanpktlenwillbediscarded.thepktlenvaluemustbedifferentfrom0.thebytewrittentothetxfifomustbedifferentfrom0.
withpktctrl0.length_config=2,thepacketlengthissettoinfiniteandtransmissionandreceptionwillcontinueuntilturnedoffmanually.asdescribedinthenextsection,thiscanbeusedtosupportpacketformatswithdifferentlengthconfigurationthannativelysupportedby1101.oneshouldmakesurethattxisnotturnoffduringthetransmissionofthefirsthalfofanybyte.refertothe1101
2.1arbitrarylengthfieldconfiguration
thepacketlengthregister,pktlen,canbereprogrammedduringreceiveandtransmit.inbinationwithfixedpacketlengthmode(pktctrl0.length_config=0),thisopensthepossibilitytohaveadifferentlengthfieldconfigurationcansupportedforvariablelengthpackets(invariablepacketlengthmodethelengthbyteisthefirstbyteafterthesyncword).atthestartofreception,thepacketlengthissetalargevalue.themcureadsoutenoughbytestointerpretthelengthfieldinthepacket.thenthepktlenvalueissetaordingtothisvalue.theendofpacketwillourwhenthebytecounterinthepackethandlerisequaltothepktlenregister.thus,themcumustbeabletoprogramthecorrectlength,beforetheinternalcounterreachesthepacketlength.
2.2packe
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 毕业设计 外文 文献 翻译