There are 64-way analog signals that are respectively connected with the input ports of four highly precise 16-channel analog switches AD7506 whose enabling signal comes from the other decoder 74HC138. The number of port allotted is 00H-3FH. It is provided in the same way as that of the switching signals . The highest bit of the signal locked that is valid when low voltage is the decoder’s enabling signal . After amplified by highly- precise operational amplifier AD624 and transmitted into voltage of 0-5 V , the analog output signals are selected by the highly precise 8-channel analog switch AD7501, amplified by isolating amplifier AD290, and transmitted into digital signals by analog-to-digital converter ADC0804, then connected to the data bus .
The digital signals are obtained by Hoyle sensor monitoring the rotating speed of the host engine in the cabin[1]. Hoyle sensor has high measuring precision. It can work reliably in seamy conditions of all kinds and send output digitally . Hoyle sensor is connected with the host engine coaxially .A counter detects signals from Hoyle sensor that vary with the rotating speed of the host engine . So the output of the counter stands for the rotating speed of the host engine, once the counting time length is given.
64路模擬信號(hào)是由4個(gè)高精度16通道模擬信號(hào)轉(zhuǎn)換芯片AD7506獨(dú)自連接的輸入端口構(gòu)成,這個(gè)轉(zhuǎn)換芯片能處理來(lái)自另一種解碼芯片74HC138的信號(hào).端口編碼為00H-3FH.轉(zhuǎn)換信號(hào)也以同樣的方式編號(hào).若低電壓為解碼器工作的允許信號(hào),信號(hào)的最高位被鎖定是必要的.經(jīng)過(guò)高精度放大器AD624的放大并輸入0-5V電壓,高精度8通道模擬轉(zhuǎn)換器AD7501選擇模擬輸出信號(hào)（或是翻譯成對(duì)模擬信號(hào)進(jìn)行取樣）,再經(jīng)緩沖放大器AD290放大信號(hào),隨后經(jīng)模數(shù)轉(zhuǎn)換器ADC0804作用轉(zhuǎn)換為數(shù)字信號(hào),最后與數(shù)據(jù)總線進(jìn)行連接.
這個(gè)數(shù)字信號(hào)傳給霍伊爾傳感器以監(jiān)控船艙內(nèi)主引擎的轉(zhuǎn)速[1].霍伊爾傳感器擁有較高的測(cè)量精度.它在各種惡劣的條件下都能可靠的工作,且以數(shù)字形式發(fā)送輸出數(shù)據(jù).霍伊爾傳感器與主引擎同軸安裝.計(jì)數(shù)器檢測(cè)來(lái)自霍伊爾傳感器的信號(hào),這個(gè)信號(hào)隨主引擎轉(zhuǎn)速而變化.因此一旦計(jì)數(shù)時(shí)長(zhǎng)給定,計(jì)數(shù)器的結(jié)果即主引擎的轉(zhuǎn)速.