·Multicarrier Communications: Lie-Liang Yang Wiley | ISBN: 0470722002 | 2009-03-03 ,696 pages Benefiting from both time-domain and frequency-domain signal processing techniques, multi
·詳細(xì)說明：Goertzel算法是DTMF信號檢測的核心，它利用二極點(diǎn)的IIR濾波器計(jì)算離散傅立葉變換值，快速有效的提取輸入信號的頻譜信息。-Goertzel algorithm is the DTMF signal examination core, it uses two extremes the IIR filter computations to be separated Fourier t
·詳細(xì)說明：雙音多頻（DTMF）信號發(fā)生器的使用源程序，vc 編寫，與《雙音多頻（DTMF）接收器的使用源程序》聯(lián)合用- The double sound multi- frequencies (DTMF) the signal generating device use source program, the vc compilation, (DTMF) Receiver Use Source p
·詳細(xì)說明：雙音多頻的DTMF信號編碼程序，產(chǎn)生DTMF信號進(jìn)行編碼。- The double sound multi- frequencies DTMF signal coded program, produces the DTMF signal to carry on the code.
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微弱信號檢測裝置
四川理工學(xué)院 劉鵬飛、梁天德、曾學(xué)明
摘要：
本設(shè)計(jì)以TI的Launch Pad為核心板，采用鎖相放大技術(shù)設(shè)計(jì)并制作了一套微弱信號檢測裝置，用以檢測在強(qiáng)噪聲背景下已知頻率微弱正弦波信號的幅度值，并在液晶屏上數(shù)字顯示出所測信號相應(yīng)的幅度值。實(shí)驗(yàn)結(jié)果顯示其抗干擾能力強(qiáng)，測量精度高。
關(guān)鍵詞：強(qiáng)噪聲；微弱信號；鎖相放大；Launch Pad
Abstract:
This design is based on the Launch Pad of TI core board, using a lock-in amplifier technique designed and produced a weak signal detection device, to measure the known frequency sine wave signal amplitude values of the weak in the high noise background, and shows the measured signal amplitude of the corresponding value in the liquid crystal screen. Test results showed that it has high accuracy and strong anti-jamming capability.
Keywords: weak signal detection; lock-in-amplifier; Launch Pad
1、引言
隨著現(xiàn)代科學(xué)技術(shù)的發(fā)展，在科研與生產(chǎn)過程中人們越來越需要從復(fù)雜高強(qiáng)度的噪聲中檢測出有用的微弱信號，因此對微弱信號的檢測成為當(dāng)前科研的熱點(diǎn)。微弱信號并不意味著信號幅度小，而是指被噪聲淹沒的信號，“微弱”也僅是相對于噪聲而言的。只有在有效抑制噪聲的條件下有選擇的放大微弱信號的幅度，才能提取出有用信號。微弱信號檢測技術(shù)的應(yīng)用相當(dāng)廣泛，在生物醫(yī)學(xué)、光學(xué)、電學(xué)、材料科學(xué)等相關(guān)領(lǐng)域顯得愈發(fā)重要。
2、方案論證
針對微弱信號的檢測的方法有很多，比如濾波法、取樣積分器、鎖相放大器等。下面就針對這幾種方法做一簡要說明。
方案一：濾波法。
在大部分的檢測儀器中都要用到濾波方法對模擬信號進(jìn)行一定的處理，例如隔離直流分量，改善信號波形，防止離散化時(shí)的波形混疊，克服噪聲的不利影響，提高信噪比等。常用的噪聲濾波器有：帶通、帶阻、高通、低通等。但是濾波方法檢測信號不能用于信號頻譜與噪聲頻譜重疊的情況，有其局限性。雖然可以對濾波器的通頻帶進(jìn)行調(diào)節(jié)，但其噪聲抑制能力有限，同時(shí)其準(zhǔn)確性與穩(wěn)定性將大打折扣。
The MAX4968/MAX4968A are 16-channel, high-linearity,high-voltage, bidirectional SPST analog switches with18I (typ) on-resistance. The devices are ideal for use inapplications requiring high-voltage switching controlledby a low-voltage control signal, such as ultrasound imagingand printers. The MAX4968A provides integrated40kI (typ) bleed resistors on each switch terminal todischarge capacitive loads. Using HVCMOS technology,these switches combine high-voltage bilateral MOSswitches and low-power CMOS logic to provide efficientcontrol of high-voltage analog signals.
Abstract: Specifications such as noise, effective number of bits (ENOB), effective resolution, and noise-free resolution inlarge part define how accurate an ADC really is. Consequently, understanding the performance metrics related to noise isone of the most difficult aspects of transitioning from a SAR to a delta-sigma ADC. With the current demand for higherresolution, designers must develop a better understanding of ADC noise, ENOB, effective resolution, and signal-to-noiseratio (SNR). This application note helps that understanding.
Many applications require a clock signal to be synchronous, phase-locked, or derived fromanother signal, such as a data signal or another clock. This type of clock circuit is important in
