超聲線性調(diào)頻信號(hào)脈沖壓縮分辨率研究
發(fā)布時(shí)間：2018-08-07 12:48
【摘要】：超聲成像作為現(xiàn)代醫(yī)學(xué)四大影像技術(shù)之一,以其強(qiáng)度低、對(duì)人體無(wú)創(chuàng)傷、價(jià)格低廉、方便、顯示方法多樣等優(yōu)點(diǎn)被廣泛的應(yīng)用。在醫(yī)學(xué)超聲成像系統(tǒng)中,圖像信噪比和分辨率是評(píng)價(jià)成像質(zhì)量的兩個(gè)重要因素。由于生物組織對(duì)于超聲效應(yīng)受限程度的限制,傳統(tǒng)單脈沖激勵(lì)超聲成像的脈沖幅值不能超過(guò)一定閾值,增加激勵(lì)信號(hào)時(shí)寬,可提高超聲功率,提高深部組織回波信噪比,但會(huì)降低分辨率。編碼激勵(lì)技術(shù)能夠在保證信噪比或探測(cè)深度的同時(shí),提高圖像的圖像分辨率。相對(duì)于傳統(tǒng)超聲脈沖回波系統(tǒng),超聲成像的編碼激勵(lì)系統(tǒng)設(shè)計(jì)和實(shí)現(xiàn)有其獨(dú)特的特點(diǎn),還有很多值得研究的地方。其中提高脈沖壓縮信噪比和分辨率,仍然是超聲成像編碼激勵(lì)技術(shù)研究的熱點(diǎn)之一。 基于編碼激勵(lì)和脈沖壓縮技術(shù),本文理論上推導(dǎo)和分析線性調(diào)頻激勵(lì)信號(hào)的帶寬、時(shí)寬、幅度包絡(luò)因素對(duì)脈沖壓縮分辨率的影響,并通過(guò)仿真和實(shí)驗(yàn)驗(yàn)證理論推導(dǎo)的正確性。針對(duì)超聲換能器頻率響應(yīng)特征,分別用不同帶寬、時(shí)寬和幅度包絡(luò)的線性調(diào)頻信號(hào)激勵(lì)超聲換能器,通過(guò)對(duì)比激勵(lì)換能器前后能量和主瓣寬度的變化,探討線性調(diào)頻信號(hào)帶寬、時(shí)寬和幅度包絡(luò)對(duì)激勵(lì)超聲換能器獲得波形脈沖壓縮信噪比和分辨率的影響。從而研究超聲線性調(diào)頻信號(hào)的最佳激勵(lì)方式。 本文研究的主要內(nèi)容： (1)理論推導(dǎo)線性調(diào)頻信號(hào)匹配濾波脈沖壓縮,通過(guò)對(duì)推導(dǎo)所得表達(dá)式分析線性調(diào)頻信號(hào)帶寬、時(shí)寬和幅度包絡(luò)參數(shù)對(duì)脈沖壓縮分辨率的影響。 (2)設(shè)計(jì)匹配濾波器,選用五組不同的帶寬,五組不同時(shí)寬和六組不同系數(shù)二次曲線幅度調(diào)制的線性調(diào)頻信號(hào)激勵(lì)匹配濾波進(jìn)行脈沖壓縮,仿真對(duì)比脈沖壓縮所得波形的分辨率。計(jì)算機(jī)控制任意波形發(fā)生器發(fā)出實(shí)驗(yàn)所用的幾組線性調(diào)頻信號(hào),激勵(lì)超聲換能器,對(duì)接收到的超聲回波信號(hào)分別通過(guò)匹配濾波,實(shí)驗(yàn)研究脈沖壓縮所得波形分辨率。 (3)針對(duì)超聲換能器具有的等效頻帶特性,選用五組不同的帶寬,五組不同時(shí)寬和六組不同系數(shù)二次曲線幅度調(diào)制的線性調(diào)頻信號(hào)激勵(lì)超聲換能器,再進(jìn)行脈沖壓縮。對(duì)比激勵(lì)換能器前后能量和主瓣寬度的變化,探討線性調(diào)頻信號(hào)的最佳激勵(lì)方式。 本文研究表明： (1)線性調(diào)頻信號(hào)脈沖壓縮的主瓣寬度與其帶寬和時(shí)寬成反比,隨著時(shí)間的增加主瓣寬度幾乎只決定信號(hào)帶寬。 (2)線性調(diào)頻信號(hào)激勵(lì)換能器能量的損失與信號(hào)帶寬成正比,與信號(hào)時(shí)寬無(wú)關(guān)。說(shuō)明線性調(diào)頻信號(hào)的帶寬越大激勵(lì)換能器后信噪比損失越大。 (3)幅度包絡(luò)調(diào)制的線性調(diào)頻信號(hào)匹配濾波脈沖壓縮所得信號(hào)的分辨率與各信號(hào)頻段所占的比重有關(guān)。若其中心頻段所占的比重越小,脈沖壓縮后主瓣寬度越窄,即分辨率越好,當(dāng)調(diào)頻信號(hào)激勵(lì)超聲換能器,信號(hào)兩端頻段能量損失較大,所以中心頻段比重的大線性調(diào)頻信號(hào)激勵(lì)超聲換能器能量損失較小,即信噪比越好。
[Abstract]:As one of the four major imaging techniques in modern medicine, ultrasound imaging has been widely used for its low intensity, no trauma, low price, convenience and diversity of display methods. In medical ultrasound imaging system, image signal-to-noise ratio and resolution are two important factors to evaluate imaging quality. Because biological tissue is limited to the ultrasonic effect Degree limit, the pulse amplitude of traditional monopulse excitation ultrasound imaging can not exceed a certain threshold, increase the width of the excitation signal, improve the ultrasonic power and improve the signal to noise ratio of the deep tissue echo, but reduce the resolution. The coding and excitation technology can improve the image resolution while ensuring the signal to noise ratio or the depth of detection. The traditional ultrasonic pulse echo system, the design and implementation of the ultrasonic imaging coding and excitation system have its unique characteristics, and there are many places to be studied. Among them, improving the signal to noise ratio and resolution of pulse compression is still one of the hotspots in the research of ultrasonic imaging coding excitation technology.
Based on the coded excitation and pulse compression technology, this paper theoretically derives and analyzes the influence of the bandwidth, time width and amplitude envelope on the resolution of the pulse compression, and proves the correctness of the theoretical derivation by simulation and experiment. The frequency response characteristics of the ultrasonic transducer are used to use the different bandwidth, time width and amplitude packet respectively. The linear frequency modulation signal of the collaterals is used to stimulate the ultrasonic transducer. By comparing the changes of the energy and the width of the main lobe, the influence of the bandwidth, time width and amplitude envelope on the signal to noise ratio and resolution of the waveform pulse compression is discussed. The optimal excitation mode of the ultrasonic linear frequency modulation signal is studied.
The main contents of this paper are as follows:
(1) the linear FM signal matching filter pulse compression is derived theoretically, and the influence of the bandwidth, the time width and the amplitude envelope parameters on the pulse compression resolution is analyzed by the derived expression.
(2) design the matched filter, select five groups of different bandwidth, five groups of different width and six different coefficient two curve amplitude modulation signal excitation matching filter to carry out pulse compression, simulate and compare the resolution of the waveform obtained by pulse compression. Computer control a few sets of linear frequency modulation used by arbitrary waveform generator. The signal is used to excite the ultrasonic transducer. The received ultrasonic echo signal is filtered by matched filtering. The waveform resolution obtained by pulse compression is experimentally studied.
(3) in view of the equivalent frequency band characteristics of the ultrasonic transducer, a linear frequency modulation signal excited ultrasonic transducer with five groups of different bandwidth, five groups of different width and six different coefficients of two curve amplitude modulation is used, and then the pulse compression is carried out. The best change of the energy and the width of the main lobe of the excitation transducer is compared. The optimal linear frequency modulation signal is discussed. The way to motivate.
The study shows that:
(1) The main lobe width of LFM signal pulse compression is inversely proportional to its bandwidth and time width, and the main lobe width almost determines the signal bandwidth with the increase of time.
(2) the energy loss of the linear frequency modulation signal excitation transducer is proportional to the signal bandwidth, and has nothing to do with the width of the signal. It shows that the greater the bandwidth of the LFM signal, the greater the signal to noise ratio loss after the transducer is stimulated.
(3) the resolution of the signal obtained by the matched filter pulse compression of the LFM signal of the amplitude envelope modulation is related to the proportion of each signal frequency band. If the proportion of the central frequency band is smaller, the width of the main lobe is narrower after the pulse compression, that is, the better the resolution is, the energy loss of the frequency band at both ends of the signal is greater when the frequency modulation signal is excited by the ultrasonic transducer. Therefore, the large LFM signal excited by the central frequency band has little energy loss, that is, the better signal to noise ratio.
【學(xué)位授予單位】：陜西師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TP391.41;R445.1
本文編號(hào)：2170070
[Abstract]:As one of the four major imaging techniques in modern medicine, ultrasound imaging has been widely used for its low intensity, no trauma, low price, convenience and diversity of display methods. In medical ultrasound imaging system, image signal-to-noise ratio and resolution are two important factors to evaluate imaging quality. Because biological tissue is limited to the ultrasonic effect Degree limit, the pulse amplitude of traditional monopulse excitation ultrasound imaging can not exceed a certain threshold, increase the width of the excitation signal, improve the ultrasonic power and improve the signal to noise ratio of the deep tissue echo, but reduce the resolution. The coding and excitation technology can improve the image resolution while ensuring the signal to noise ratio or the depth of detection. The traditional ultrasonic pulse echo system, the design and implementation of the ultrasonic imaging coding and excitation system have its unique characteristics, and there are many places to be studied. Among them, improving the signal to noise ratio and resolution of pulse compression is still one of the hotspots in the research of ultrasonic imaging coding excitation technology.
Based on the coded excitation and pulse compression technology, this paper theoretically derives and analyzes the influence of the bandwidth, time width and amplitude envelope on the resolution of the pulse compression, and proves the correctness of the theoretical derivation by simulation and experiment. The frequency response characteristics of the ultrasonic transducer are used to use the different bandwidth, time width and amplitude packet respectively. The linear frequency modulation signal of the collaterals is used to stimulate the ultrasonic transducer. By comparing the changes of the energy and the width of the main lobe, the influence of the bandwidth, time width and amplitude envelope on the signal to noise ratio and resolution of the waveform pulse compression is discussed. The optimal excitation mode of the ultrasonic linear frequency modulation signal is studied.
The main contents of this paper are as follows:
(1) the linear FM signal matching filter pulse compression is derived theoretically, and the influence of the bandwidth, the time width and the amplitude envelope parameters on the pulse compression resolution is analyzed by the derived expression.
(2) design the matched filter, select five groups of different bandwidth, five groups of different width and six different coefficient two curve amplitude modulation signal excitation matching filter to carry out pulse compression, simulate and compare the resolution of the waveform obtained by pulse compression. Computer control a few sets of linear frequency modulation used by arbitrary waveform generator. The signal is used to excite the ultrasonic transducer. The received ultrasonic echo signal is filtered by matched filtering. The waveform resolution obtained by pulse compression is experimentally studied.
(3) in view of the equivalent frequency band characteristics of the ultrasonic transducer, a linear frequency modulation signal excited ultrasonic transducer with five groups of different bandwidth, five groups of different width and six different coefficients of two curve amplitude modulation is used, and then the pulse compression is carried out. The best change of the energy and the width of the main lobe of the excitation transducer is compared. The optimal linear frequency modulation signal is discussed. The way to motivate.
The study shows that:
(1) The main lobe width of LFM signal pulse compression is inversely proportional to its bandwidth and time width, and the main lobe width almost determines the signal bandwidth with the increase of time.
(2) the energy loss of the linear frequency modulation signal excitation transducer is proportional to the signal bandwidth, and has nothing to do with the width of the signal. It shows that the greater the bandwidth of the LFM signal, the greater the signal to noise ratio loss after the transducer is stimulated.
(3) the resolution of the signal obtained by the matched filter pulse compression of the LFM signal of the amplitude envelope modulation is related to the proportion of each signal frequency band. If the proportion of the central frequency band is smaller, the width of the main lobe is narrower after the pulse compression, that is, the better the resolution is, the energy loss of the frequency band at both ends of the signal is greater when the frequency modulation signal is excited by the ultrasonic transducer. Therefore, the large LFM signal excited by the central frequency band has little energy loss, that is, the better signal to noise ratio.
【學(xué)位授予單位】：陜西師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TP391.41;R445.1
【參考文獻(xiàn)】
相關(guān)期刊論文 前8條
1 龐勇,韓焱;超聲成像方法綜述[J];測(cè)試技術(shù)學(xué)報(bào);2001年04期
2 蔚建斌;齊曉慧;陳自力;;脈沖壓縮在超寬帶雷達(dá)中的應(yīng)用[J];電光與控制;2006年01期
3 劉波;郭建中;;載頻調(diào)制二相編碼激勵(lì)的超聲成像信噪比提高研究[J];電子學(xué)報(bào);2011年11期
4 傅娟;韋崗;黃慶華;;基于幅度加權(quán)的預(yù)失真線性調(diào)頻超聲編碼激勵(lì)[J];電子與信息學(xué)報(bào);2013年02期
5 彭旗宇,高上凱;醫(yī)學(xué)超聲成像中的編碼激勵(lì)技術(shù)及其應(yīng)用[J];生物醫(yī)學(xué)工程學(xué)雜志;2005年01期
6 谷金宏;王素品;萬(wàn)明習(xí);;發(fā)射調(diào)頻信號(hào)提高醫(yī)學(xué)超聲圖像的信號(hào)噪聲比[J];西安交通大學(xué)學(xué)報(bào);2007年06期
7 王威琪;周國(guó)輝;汪源源;他得安;余建國(guó);;關(guān)于人體信號(hào)和醫(yī)學(xué)超聲信號(hào)[J];現(xiàn)代臨床醫(yī)學(xué)生物工程學(xué)雜志;2006年05期
8 賈寶賢,邊文鳳,趙萬(wàn)生,王振龍;壓電超聲換能器的應(yīng)用與發(fā)展[J];壓電與聲光;2005年02期
，本文編號(hào)：2170070
本文鏈接：http://sikaile.net/yixuelunwen/fangshe/2170070.html
最近更新
教材專著
