蔡澤利+譚振江
摘 要: 在物聯(lián)網(wǎng)環(huán)境下進(jìn)行無線節(jié)點自動監(jiān)控數(shù)據(jù)采集,提高數(shù)據(jù)檢測和診斷分析能力,提出基于動態(tài)增益控制和DSP高速信號處理的物聯(lián)網(wǎng)智能無線節(jié)點自動監(jiān)控數(shù)據(jù)采集系統(tǒng)設(shè)計方法?;谖C(jī)總線技術(shù)進(jìn)行無線節(jié)點自動監(jiān)控數(shù)據(jù)采集系統(tǒng)的總體設(shè)計,系統(tǒng)主要包括DSP處理器和PCI總線兩大功能模塊設(shè)計,數(shù)據(jù)采集的傳感器基陣由多傳感信息融合的無線監(jiān)測節(jié)點組成,設(shè)計收發(fā)轉(zhuǎn)換電路和功率放大電路實現(xiàn)采集數(shù)據(jù)的信號放大和數(shù)/模轉(zhuǎn)換。采用動態(tài)增益控制方法實現(xiàn)采集數(shù)據(jù)的放大和濾波處理,基于DSP信號處理器進(jìn)行自動監(jiān)控數(shù)據(jù)采集系統(tǒng)的集成設(shè)計。測試結(jié)果表明,采用該系統(tǒng)進(jìn)行物聯(lián)網(wǎng)智能無線節(jié)點自動監(jiān)控數(shù)據(jù)采集,能實現(xiàn)持續(xù)的大于15 MB/s的實時數(shù)據(jù)采集和記錄,總線持續(xù)數(shù)據(jù)傳輸速率超過20 MB/s,峰值傳輸速率也可超過33 MB/s,滿足實時記錄無線節(jié)點自動監(jiān)控數(shù)據(jù)的需求。
關(guān)鍵詞: 物聯(lián)網(wǎng); 無線節(jié)點; 監(jiān)控數(shù)據(jù); 采集系統(tǒng); DSP; 數(shù)模轉(zhuǎn)換
中圖分類號: TN915?34; TN911 文獻(xiàn)標(biāo)識碼: A 文章編號: 1004?373X(2018)04?0183?04
Abstract: The automatic monitoring data acquisition of wireless nodes under the environment of Internet of Things (IoT) can improve the capability of data detection and diagnosis analysis. Therefore, a dynamic gain control and DSP high?speed signal processing based design method of automatic monitoring data acquisition system for IoT intelligent wireless nodes is proposed. During the overall design of automatic monitoring data acquisition system for wireless nodes based on the computer bus technology, two functional modules of DSP processor and PCI bus are designed. The sensor array of data acquisition is composed of multi?sensor information fused wireless monitoring nodes. The transceiver circuit and power amplifier circuit are designed to realize signal amplification and digital?to?analogue conversion (DAC) for data acquisition. The dynamic gain control method is used to achieve the amplification and filtering of data acquisition. The integrated design of automatic monitoring data acquisition system based on DSP signal processor is performed. The test results show that the system for automatic monitoring data acquisition of IoT intelligent wireless nodes can realize over 15 MB/s continuous real?time data acquisition and recording, with the continuous data transmission rate of the bus higher than 20 MB/s, and the peak transmission rate higher than 33MB/s, which can meet the requirement of real?time recording of automatic monitoring data for wireless nodes.
Keywords: IoT; wireless node; monitoring data; acquisition system; DSP; DAC
0 引 言
研究物聯(lián)網(wǎng)智能無線節(jié)點自動監(jiān)控數(shù)據(jù)采集系統(tǒng)的優(yōu)化設(shè)計方法,在信號檢測、計量、測控等領(lǐng)域具有廣闊的應(yīng)用前景。傳統(tǒng)方法設(shè)計物聯(lián)網(wǎng)監(jiān)控數(shù)據(jù)數(shù)據(jù)采集系統(tǒng)存在數(shù)據(jù)采集實時性不好,不適用于外場測試、現(xiàn)場檢測等應(yīng)用需求,需要進(jìn)行系統(tǒng)改進(jìn)設(shè)計[1]。對此,提出基于動態(tài)增益控制和DSP高速信號處理的智能無線節(jié)點自動監(jiān)控數(shù)據(jù)采集系統(tǒng)設(shè)計方法,并進(jìn)行系統(tǒng)測試分析,得出有效性結(jié)論。
1 數(shù)據(jù)采集系統(tǒng)總體設(shè)計
1.1 原理分析及系統(tǒng)總體構(gòu)架
本文設(shè)計的數(shù)據(jù)采集系統(tǒng)是采用多節(jié)點分布的傳感器網(wǎng)絡(luò)進(jìn)行監(jiān)控數(shù)據(jù)采集,數(shù)據(jù)采集系統(tǒng)建立在物聯(lián)網(wǎng)體系結(jié)構(gòu)基礎(chǔ)上,首先采用物聯(lián)網(wǎng)環(huán)境下的無線傳感通信組網(wǎng)技術(shù)進(jìn)行節(jié)點分布式設(shè)計,構(gòu)建數(shù)據(jù)感知層,實現(xiàn)對原始監(jiān)控數(shù)據(jù)的實時讀取[2],采用時鐘控制電路進(jìn)行數(shù)據(jù)采集過程中的中斷控制和增益放大控制,對采集原始數(shù)據(jù)輸入到匹配濾波器中進(jìn)行噪聲和干擾的濾波檢測,進(jìn)行匹配放大。確定動態(tài)增益范圍,將放大輸出的采集數(shù)據(jù)和原始信號進(jìn)行增益放大和多模控制,以高速DSP信號處理芯片為內(nèi)核,進(jìn)行采集數(shù)據(jù)分析加工和信號處理[3],并經(jīng)過PCI總線及橋接電路實現(xiàn)系統(tǒng)的觸發(fā)控制。系統(tǒng)的電源設(shè)計采用I/O電源、實時電源和時鐘電源三種模式,設(shè)計掉電復(fù)位電路,防止電源中斷導(dǎo)致信息數(shù)據(jù)丟失[4]。基陣接收的無線節(jié)點自動監(jiān)控數(shù)據(jù)一般都是幾微伏到幾百毫伏不等,因此在進(jìn)行數(shù)據(jù)采集過程中必須通過模擬信號預(yù)處理機(jī)進(jìn)行放大,因此選擇合適的放大器即可,用動態(tài)增益控制方法實現(xiàn)采集數(shù)據(jù)的放大和濾波處理,采用微機(jī)總線技術(shù)進(jìn)行無線節(jié)點自動監(jiān)控數(shù)據(jù)采集系統(tǒng)的總體設(shè)計。根據(jù)上述設(shè)計分析,構(gòu)造物聯(lián)網(wǎng)智能無線節(jié)點自動監(jiān)控數(shù)據(jù)采集系統(tǒng)的總體設(shè)計框圖如圖1所示。endprint
根據(jù)圖1分析得知,本文設(shè)計的數(shù)據(jù)采集系統(tǒng)的核心控制模塊部分主要包括了DSP信號處理器、模擬信號預(yù)處理機(jī)、外部I/O設(shè)備、數(shù)據(jù)存儲器等,物聯(lián)網(wǎng)無線傳感器基陣接收的監(jiān)控數(shù)據(jù)通過模擬信號預(yù)處理機(jī)放大、濾波后,進(jìn)行數(shù)字FIR濾波,接收信號處理、頻譜分析、自動增益控制等信息處理方法,實現(xiàn)監(jiān)控數(shù)據(jù)的自動增益放大、數(shù)/模轉(zhuǎn)換和數(shù)據(jù)存儲等[5]。
1.2 系統(tǒng)的技術(shù)指標(biāo)分析
物聯(lián)網(wǎng)環(huán)境下無線節(jié)點自動監(jiān)控數(shù)據(jù)采集系統(tǒng)采用高速A/D芯片AD9225進(jìn)行采樣信息調(diào)制,其采樣頻率為12 MHz,采用32位VME總線擴(kuò)展技術(shù)構(gòu)建無線節(jié)點自動監(jiān)控數(shù)據(jù)的采集系統(tǒng)的可編程專用集成總線,設(shè)計的無線節(jié)點自動監(jiān)控數(shù)據(jù)系統(tǒng)具有12通道DMA,0.8~1.2 V的核心電壓,3.3 V的I/O電壓,采用2線制接口作為輸出接口電路,在ARM Cortex?M3內(nèi)核中進(jìn)行控制系統(tǒng)的嵌入式開發(fā),本文設(shè)計的數(shù)據(jù)采集系統(tǒng)的技術(shù)指標(biāo)描述如下:
1) 自動監(jiān)控數(shù)據(jù)的調(diào)幅動態(tài)范圍為-40~40 dB,寬帶基陣阻抗匹配濾波的放大量為80 dB,輸出采集數(shù)據(jù)的頻譜幅度為[±10 V];
2) 監(jiān)控數(shù)據(jù)的采樣通道:12通道同步、異步輸入;
3) 讀取監(jiān)控數(shù)據(jù)A/D采樣值采樣率:大于100 MHz;
4) D/A轉(zhuǎn)換器的頻譜控制分辨率:12位(至少);
5) PCI總線接收自動監(jiān)控數(shù)據(jù)的D/A分辨率:12位(至少);
6) D/A轉(zhuǎn)換器進(jìn)行數(shù)/模轉(zhuǎn)換速率:大于100 kHz。
2 系統(tǒng)硬件開發(fā)設(shè)計
2.1 器件選擇
本文采用模塊化的硬件電路設(shè)計方法進(jìn)行數(shù)據(jù)采集系統(tǒng)開發(fā)設(shè)計。在物聯(lián)網(wǎng)自動監(jiān)控數(shù)據(jù)采集硬件實現(xiàn)中,需要借助于專用的高速信號硬件,如DSP、現(xiàn)場可編程門邏輯陣列FPGA等實現(xiàn)信號集成處理系統(tǒng)主要包括了DSP處理器和PCI總線兩大功能模塊設(shè)計,根據(jù)數(shù)據(jù)采集運算量的要求,DSP的最低速度應(yīng)大于[25×20=500 MHz],整機(jī)功耗不大于12 W,應(yīng)選擇低壓低功耗DSP芯片,因此在數(shù)據(jù)采集系統(tǒng)DSP設(shè)計中,選用高速STC89C52芯片進(jìn)行無線監(jiān)控數(shù)據(jù)采集的基線漂移控制,選擇ADI公司的ADSP21160處理器系統(tǒng)作為核心處理器件,該芯片具有16位定點DSP內(nèi)核,具備40位移位器,支持片外同步或異步存儲器,暫存數(shù)據(jù)的輸出模式為SRAM。外圍器件主要是對A/D轉(zhuǎn)換器和D/A轉(zhuǎn)換器的選擇,本文選擇ADI公司的高速A/D芯片作為外圍器件進(jìn)行自動監(jiān)控數(shù)據(jù)的A/D采集,其采樣頻率為12 MHz, 晶體電路ADI的串行D/A轉(zhuǎn)換選擇AD5545作為外圍器件,通過晶體電路設(shè)計,使輸出時鐘頻率精確、穩(wěn)定[6]。
2.2 硬件電路的模塊化設(shè)計
根據(jù)對系統(tǒng)總體構(gòu)架與技術(shù)指標(biāo)分析,在進(jìn)行器件優(yōu)選的基礎(chǔ)上,進(jìn)行物聯(lián)網(wǎng)環(huán)境下無線節(jié)點自動監(jiān)控數(shù)據(jù)采集系統(tǒng)的硬件模塊化設(shè)計。其采用32位VME總線擴(kuò)展技術(shù)構(gòu)建無線節(jié)點自動監(jiān)控數(shù)據(jù)的采集系統(tǒng)的可編程專用集成總線,用16位DSP和32位DSP進(jìn)行系統(tǒng)硬件電路的模塊化開發(fā),本文設(shè)計的數(shù)據(jù)采集系統(tǒng)主要包括物聯(lián)網(wǎng)無線節(jié)點數(shù)據(jù)A/D模塊、模擬信號預(yù)處理模塊、時鐘控制模塊、收發(fā)轉(zhuǎn)換模塊、自動增益控制模塊以及功率放大模塊等[7],對各個模塊的電路設(shè)計描述如下:
1) A/D模塊。A/D模塊是實現(xiàn)對物聯(lián)網(wǎng)無線節(jié)點數(shù)據(jù)的A/D采樣和數(shù)/模轉(zhuǎn)換控制,A/D電路采用2片AD5545芯片組成D/A收發(fā)裝置,采集系統(tǒng)的AD5545采用單5 V供電。為了減少數(shù)字電路和模擬電路之間的相互干擾,在數(shù)據(jù)采集系統(tǒng)的I/O輸出終端設(shè)計功率放大器,完成無線終端智能通信信號的數(shù)/模轉(zhuǎn)換;為了減少噪聲,采用10[μF,]0.1[μF]和0.001[μF]的電容進(jìn)行濾波處理,輸出的VAA為5 V電壓。A/D電路設(shè)計見圖2。
2) 模擬信號預(yù)處理模塊。模擬信號預(yù)處理是實現(xiàn)對無線節(jié)點監(jiān)控數(shù)據(jù)采集后的濾波、放大和檢波等預(yù)處理的功能,該模塊由一款16位分辨率的可編程邏輯芯片組成[8],輸出接口為同步多片AD5545,電路設(shè)計如圖3所示。
3) 時鐘控制模塊。時鐘控制模塊是實現(xiàn)監(jiān)控數(shù)據(jù)采集的時鐘控制和周期采樣控制功能,采用通用PPI模式構(gòu)造時鐘控制模塊[9],實現(xiàn)多樣化的數(shù)據(jù)捕捉和信號獲取,設(shè)置DMA參數(shù)實現(xiàn)最高65 MHz的監(jiān)控數(shù)據(jù)時鐘采樣,時鐘控制模塊電路設(shè)計如圖4所示。
4) 自動增益控制模塊和功率放大模塊的集成設(shè)計。利用同步多片AD5545進(jìn)行自動增益控制設(shè)計,放大模塊采用DSP進(jìn)行信號處理和核心控制設(shè)計,設(shè)計收發(fā)轉(zhuǎn)換電路和功率放大電路實現(xiàn)采集數(shù)據(jù)的信號放大和數(shù)/模轉(zhuǎn)換[10]。結(jié)合CPLD編程技術(shù)將DSP發(fā)送的物聯(lián)網(wǎng)環(huán)境下無線終端智能通信并行數(shù)據(jù)進(jìn)行模塊化并行處理,在D/A輸出端加濾波器,采用動態(tài)增益控制方法實現(xiàn)采集數(shù)據(jù)的放大和濾波處理,最后得到自動監(jiān)控數(shù)據(jù)采集系統(tǒng)的集成電路。
3 實驗測試分析
為了測試本文設(shè)計的物聯(lián)網(wǎng)智能無線節(jié)點自動監(jiān)控數(shù)據(jù)采集系統(tǒng)在實現(xiàn)數(shù)據(jù)采集和無線節(jié)點自動監(jiān)控信息實時記錄中的性能,進(jìn)行系統(tǒng)測試和仿真實驗分析,實驗平臺搭建在軟件仿真器(Simulator)、硬件仿真器(Emulator)基礎(chǔ)上,使用Matlab Simulator是軟件仿真分析數(shù)據(jù)采集輸出性能,并執(zhí)行信號處理程序的初期調(diào)試和仿真,設(shè)定信號采集系統(tǒng)的工作頻率為250 MHz,DSP工作到600 MHz產(chǎn)生中斷信號,鎖相環(huán)輸出頻率為400 MHz,倍頻數(shù)為10,配置串口0發(fā)送數(shù)據(jù)的時鐘頻率,設(shè)定SPORT0_TCLKDIV為4,根據(jù)上述測試環(huán)境設(shè)定,得到自動監(jiān)控數(shù)據(jù)采集輸出如圖5所示。
分析圖5結(jié)果得知,采用本文方法設(shè)計自動監(jiān)控數(shù)據(jù)采集系統(tǒng),能實現(xiàn)持續(xù)大于15 MB/s的實時數(shù)據(jù)采集和記錄,總線持續(xù)數(shù)據(jù)傳輸速率超過20 MB/s,峰值傳輸速率也可超過33 MB/s,滿足實時記錄無線節(jié)點自動監(jiān)控數(shù)據(jù)的需求。endprint
4 結(jié) 論
本文提出基于動態(tài)增益控制和DSP高速信號處理的物聯(lián)網(wǎng)智能無線節(jié)點自動監(jiān)控數(shù)據(jù)采集系統(tǒng)設(shè)計方法。研究結(jié)果表明,采用改進(jìn)物聯(lián)網(wǎng)智能無線節(jié)點自動監(jiān)控數(shù)據(jù)采集,數(shù)據(jù)的實時數(shù)據(jù)采集性能較好,能實現(xiàn)數(shù)據(jù)的正確采樣,滿足實時記錄無線節(jié)點自動監(jiān)控數(shù)據(jù)的需求。
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