Gigabit Digital Filter Bank: Digital Backend Subsystem in the VERA Data-Acquisition System

摘要

TheVERAterminalisanewdata-acquisitionsystemdevelopedfortheVERAproject,whichisaprojecttoconstructanewJapaneseVLBIarraydedicatedtomakea3-DmapofourMilkyWayGalaxyintermsofhigh-precisionastrometry.Newtechnology,agigabitdigitalfilter,wasintroducedinthedevelopment.Theimportanceandadvantagesofadigitalfilterforradioastronomyhavebeenstudiedasfollows:(1)thedigitalfiltercanrealizeavarietyofobservationmodesandmaintaincompatibilitywithdifferentdata-acquisitionsystems(Kiuchietal.1997andIguchietal.2000a),(2)thefoldingnoiseoccurringinthesamplingprocesscanbereducedbycombinationwithahigher-ordersamplingtechnique(Iguchi,Kawaguchi2002),(3)andanidealsharpcut-offbandedgeandaflatamplitude/phaseresponsesareapproachedbyusingalargenumberoftapsavailabletouseLSIofalargenumberoflogiccells(Iguchietal.2000a).WedevelopedthecustomFiniteImpulseResponsefilterchipsandmanufacturedtheGigabitDigitalFilterBanks(GDFBs)asadigitalbackendsubsystemintheVERAterminal.Inthispaper,thedesignanddevelopmentoftheGDFBarepresentedindetail,andtheperformancesanddemonstrationsofthedevelopedGDFBareshown.