Thereare64-wayanalogsignalsthatarerespectivelyconnectedwiththeinputportsoffourhighlyprecise16-channelanalogswitchesAD7506whoseenablingsignalcomesfromtheotherdecoder74HC138.Thenumberofportallottedis00H-3FH.Itisprovidedinthesamewayasthatoftheswitchingsignals.Thehighestbitofthesignallockedthatisvalidwhenlowvoltageisthedecoder’senablingsignal.Afteramplifiedbyhighly-preciseoperationalamplifierAD624andtransmittedintovoltageof0-5V,theanalogoutputsignalsareselectedbythehighlyprecise8-channelanalogswitchAD7501,amplifiedbyisolatingamplifierAD290,andtransmittedintodigitalsignalsbyanalog-to-digitalconverterADC0804,thenconnectedtothedatabus.
ThedigitalsignalsareobtainedbyHoylesensormonitoringtherotatingspeedofthehostengineinthecabin[1].Hoylesensorhashighmeasuringprecision.Itcanworkreliablyinseamyconditionsofallkindsandsendoutputdigitally.Hoylesensorisconnectedwiththehostenginecoaxially.AcounterdetectssignalsfromHoylesensorthatvarywiththerotatingspeedofthehostengine.Sotheoutputofthecounterstandsfortherotatingspeedofthehostengine,oncethecountingtimelengthisgiven.
64路模拟信号是由4个高精度16通道模拟信号转换芯片AD7506独自连接的输入端口构成,这个转换芯片能处理来自另一种解码芯片74HC138的信号.端口编码为00H-3FH.转换信号也以同样的方式编号.若低电压为解码器工作的允许信号,信号的最高位被锁定是必要的.经过高精度放大器AD624的放大并输入0-5V电压,高精度8通道模拟转换器AD7501选择模拟输出信号(或是翻译成对模拟信号进行取样),再经缓冲放大器AD290放大信号,随后经模数转换器ADC0804作用转换为数字信号,最后与数据总线进行连接.
这个数字信号传给霍伊尔传感器以监控船舱内主引擎的转速[1].霍伊尔传感器拥有较高的测量精度.它在各种恶劣的条件下都能可靠的工作,且以数字形式发送输出数据.霍伊尔传感器与主引擎同轴安装.计数器检测来自霍伊尔传感器的信号,这个信号随主引擎转速而变化.因此一旦计数时长给定,计数器的结果即主引擎的转速.
