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預(yù)調(diào)制多陪集采樣系統(tǒng)
2022年電子技術(shù)應(yīng)用第4期
黃 振,柏正堯
云南大學(xué) 信息學(xué)院,云南 昆明650500
摘要: 目前,壓縮采樣系統(tǒng)主要有隨機(jī)解調(diào)器、調(diào)制寬帶轉(zhuǎn)換器和多陪集采樣3種,其中,多陪集采樣的系統(tǒng)框架簡(jiǎn)單、重構(gòu)成功率高,但用硬件實(shí)現(xiàn)時(shí)面臨兩個(gè)難題,一是低速模數(shù)轉(zhuǎn)換器(ADC)的輸入模擬帶寬存在上限,二是難以實(shí)現(xiàn)各通道上的精準(zhǔn)時(shí)延。借鑒調(diào)制寬帶轉(zhuǎn)換器在采樣前先對(duì)輸入信號(hào)進(jìn)行預(yù)調(diào)制的思想,將預(yù)調(diào)制與多陪集采樣結(jié)合,提出了預(yù)調(diào)制多陪集采樣系統(tǒng)。采樣前,在采樣系統(tǒng)各通道上,由隨機(jī)序列發(fā)生器產(chǎn)生周期單脈沖序列,對(duì)輸入信號(hào)進(jìn)行頻譜調(diào)制以降低采樣前信號(hào)的模擬帶寬;然后,調(diào)制信號(hào)由低速ADC進(jìn)行采樣,且各通道上的低速ADC與隨機(jī)序列發(fā)生器列共用同一個(gè)控制時(shí)鐘;最后,采用多信號(hào)分類算法(MUSIC)算法近乎無失真地重構(gòu)出輸入信號(hào)。仿真實(shí)驗(yàn)結(jié)果表明,當(dāng)以15%的奈奎斯特采樣速率對(duì)輸入信號(hào)進(jìn)行壓縮采樣時(shí),重構(gòu)信號(hào)的均方誤差僅為10-5量級(jí)。這驗(yàn)證了該采樣系統(tǒng)的可行性,有效解決了多陪集采樣系統(tǒng)的兩個(gè)難題。
中圖分類號(hào): TN911
文獻(xiàn)標(biāo)識(shí)碼: A
DOI:10.16157/j.issn.0258-7998.212221
中文引用格式: 黃振,柏正堯. 預(yù)調(diào)制多陪集采樣系統(tǒng)[J].電子技術(shù)應(yīng)用,2022,48(4):48-52.
英文引用格式: Huang Zhen,Bai Zhengyao. Pre-modulated multi-coset sampling system[J]. Application of Electronic Technique,2022,48(4):48-52.
Pre-modulated multi-coset sampling system
Huang Zhen,Bai Zhengyao
School of Information Science and Engineering,Yunnan University,Kunming 650500,China
Abstract: At present, the compressed sampling system mainly includes three sampling system: random demodulator,modulated wideband converter and multi-coset sampling, among them, the system framework of multi-coset sampling is simple and has a high reconstruction success rate. But, the multi-coset sampling faces two difficulties in hardware implementation, one is that there is an upper limit on the input analog bandwidth of the low-speed analog-to-digital converter(ADC), and the other is it′s difficult to achieve precise delays on each channel. This paper draws on the ideal of modulated wideband converter which the input signal is pre-modulated before sampling, proposes the pre-modulated multi-coset sampling system which combines pre-modulation with multi-coset sampling. Before sampling, the generate periodic single-pulse sequences is generated by a random sequence generator in each channel of the sampling system, and the input signal is spectrally modulated to reduce the analog bandwidth of the signal before sampling. Then, the modulated signal is sampled by the low-speed ADC, and each channel of low-speed ADC and random sequence generator share a same control clock. Finally, the multiple signal classification algorithm(MUSIC) is used to reconstruct the input signal without distortion. The simulation results show that the mean square error of the reconstructed signal is at the order of 10-5 when the input signal is compressed and sampled at 15% Nyquist sampling rate. This verifies the feasibility of the sampling system in this paper, and the sampling system effectively overcome the two problems of the multi-coset sampling system.
Key words : compressed sensing;multi-coset sampling;pre-modulated;MUSIC algorithm;modulated wideband converter

0 引言

    隨著信息技術(shù)的不斷飛速發(fā)展,學(xué)者在研究信號(hào)處理的前沿領(lǐng)域取得了卓越成就,隨著對(duì)前沿信息技術(shù)探知的增加,雖然科技人員已研制出高性能的ADC,但現(xiàn)有最高采樣速率的ADC仍無法滿足學(xué)者們對(duì)更高頻率的信號(hào)頻譜及信號(hào)特征的研究,且采樣速率超過1 GHz的商用ADC價(jià)格非常昂貴[1]。針對(duì)具有稀疏特性的信號(hào),提出的壓縮感知(Compressed Sensing,CS)理論[2-4]緩解了ADC采樣速率的壓力,實(shí)現(xiàn)對(duì)信號(hào)的采樣和壓縮同步進(jìn)行,并刪除了冗余信息,降低了數(shù)據(jù)運(yùn)算量,緩解了硬件壓力,然后再由重構(gòu)算法實(shí)現(xiàn)從低維的壓縮數(shù)據(jù)中重構(gòu)出輸入信號(hào)。

    目前,信號(hào)處理中的壓縮采樣系統(tǒng)[5-6]主要有隨機(jī)解調(diào)器(Random Demodulator,RD)[7]、多陪集采樣(Multi-Coset Sampling,MCS)[1,6-8]調(diào)制寬帶轉(zhuǎn)換器(Modulated Wideband Converter,MWC)[1,6-7,9]3種采樣系統(tǒng)。RD是單通道多音頻模型的欠采樣,對(duì)輸入信號(hào)模型比較敏感,當(dāng)信號(hào)是非線譜信號(hào)時(shí),重構(gòu)誤差和重構(gòu)計(jì)算量均較大,因此無法普遍適用于所有的寬帶信號(hào)[1]。MWC采樣系統(tǒng)是多通道均勻亞奈奎斯特采樣,隨著采樣系統(tǒng)通道數(shù)的增加,使得產(chǎn)生各通道上非相關(guān)偽隨機(jī)序列的難度成幾何倍數(shù)地增加,同時(shí)偽隨機(jī)序列的跳變速率不小于奈奎斯特采樣速率。MCS是多通道周期非均勻亞奈奎斯特采樣,通過調(diào)整各通道上的時(shí)延實(shí)現(xiàn)頻域內(nèi)不同權(quán)值的頻譜裁剪,在硬件實(shí)現(xiàn)時(shí)各通道上的時(shí)延器很難產(chǎn)生理論中的理想時(shí)延,同時(shí)MCS在接收信號(hào)前未先進(jìn)行低通濾波,導(dǎo)致ADC的接收輸入模擬帶寬必須不小于輸入信號(hào)的模擬帶寬。




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作者信息:

黃  振,柏正堯

(云南大學(xué) 信息學(xué)院,云南 昆明650500)




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