神经信号采集系统中模拟前端与ARM9适配电路的研制

本文探讨了基于ARM9和LabVIEW的多路神经信号采集系统,其中包括八通道模拟前端电路。为与系统中S3C2410内置的ADC可靠配接,本文特别自行设计出了双极性转单极性并线性限幅的完整电路,并分析了其设计思想。相应电路及设计技术对应用嵌入式系统技术的多路微弱信号采集等电路研制有实际参考价值。     

MCP6S9X：可编程增益放大器

美国微芯科技公司推出新款可编程增益放大器系列MCP6S9X，可以在运行过程中设定系统增益和信号路径．当终端应用开启时．能增加系统自我校准和其他系统操作调节的灵活性。     

基于LabVIEW的多路VF/IF系列电路测试系统设计

设计了一种VF/IF系列电路测试系统,计算机通过LabVIEW程序控制电压信号Vin,对三路VF/IF系列电路输出的相应脉冲信号进行采集和处理,实现了VF/IF系列电路功能和参数的自动测试。     

Microchip推出低电压、低电流、增益稳定的运算放大器

Microchip Technology最新推出 MCP60 4 X系列运算放大器 ,具有增益稳定、轨对轨输入 /输出功能 ,是电池供电的低电流、低电压应用的最佳选择。MCP60 4 1、 MCP60 4 2、 MCP60 4 3和 MCP60 4 4运算放大器提供轨对轨输入和输出 ,工作电压范围从 5 .5伏低至 1 .4伏。新器件 1 4k Hz的增益稳定的增益带宽产品( GBWP) ,1微安的最大静态电流使电路不需要采用昂贵的稳压电路 ,同时保持较低的功耗。新器件的工作温度从零下 40摄氏度到 85摄氏度 ,典型静态电流为 60 0纳安 ,从而延长电池寿命。Microchip配合 MCP60 4 X产品系列还推出了F…     

基于Cortex-M4的智能控制器设计

设计了一款基于Cortex-M4的智能控制器,包含6路DI、6路DO、2路脉冲输出、4路A/D、2路D/A、1路RS232通讯、1路RS485通讯、1路以太网通讯和1个4.3英寸触摸显示屏。主芯片采用STM32F429ZGT6处理器,A/D电路是基于MCP3204的12位分辨率转换电路,采集模拟量电压;D/A电路是基于压流转换芯片XTR111的转换电路,输出4～20 mA电流,分辨率为0.05%。采用隔离电源模块组成全隔离供电系统。采用4.3英寸触摸显示屏进行人机交互。采用模块化设计,方便硬件扩展与裁剪。内存容量33 MB,可以嵌入实时操作系统、智能控制算法和图形界面。采用该控制器实现对暖箱的温度控制,超调<1.3℃,稳态误差<0.1℃。     

基于PIC单片机和AD7705的高精度信号采集系统设计

提出了一种基于PIC单片机和AD7705实现模拟信号的高精度采集的设计方案.选用PIC18F458为主控制芯片,AD7705为A/D转换器,通过SPI通讯接口进行连接,其中利用6N136对接口进行光电隔离来提高通讯可靠性.根据所采集信号的不同范围,在信号输入前端加入滤波电路然后通过MCP602和反馈电阻进行相应倍数的精密放大以满足AD7705的采集范围要求,并且采用MCP1525为AD7705提供基准电压以保证信号采集的精准度.此外,为了使PIC18F458能够保持高效稳定地工作,采用HT7044组成单片机复住电路.实验结果表明,该系统应用于工业现场进行模拟信号采集,无论是采集精度还是稳定性都达到了理想的效果,实现了模拟信号的高精度采集.     

一种X线探测器信号采集电路的设计

该文利用a-Si PIN结构X线平板探测器设计对应的信号采集电路,读出经由探测器阵列感测到的模拟信号并转化为数字信号供后续处理。用德州仪器成熟的商用芯片,经过电路设计、PCB制作实现硬件部分。控制代码使用VerilogHDL硬件描述语言编写,通过Modelsim软件仿真,最后利用Quartus II软件综合、布局布线,使用AlteraCycloneIV系列现场可编程门阵列(FPGA)实现信号输出从而控制信号采集电路的运行。最终实验与测试验证了电路的功能,成功获取X光的模拟和数字信号。验证了电路的功能,并为低剂量X光探测器信号的采集提供了一种设计参考。     

基于MC9S12XS128的汽车BCM的设计与实现

为某车型设计了一款车身中央控制器BCM,实现了门锁控制、灯光控制、雨刷控制、车窗控制、LIN通信、RKE通信等功能.BCM采用Freescale的S12系列16位微处理器MC9S12XS128进行设计,通过多路开关检测芯片MC33993进行IO扩展.解决了多路开关、处理器IO管脚有限条件下的开关信号采集,开关信号检测程...     

新一代电能计量模拟前端

正MCP3913和MCP3914分别集成了6和8个24位ΔΣADC,具备94.5dB的SINAD、-106.5dB的THD和112dB的SFDR,适用于高精度信号采集和更高性能的最终产品。其中,MCP3914额外多出两个ADC,增加了单一芯片所能监控的传感器数量,有助于降低产品成本     

基于FPGA的红外光谱信号采集系统设计

介绍了一种基于现场可编程门阵列（field-programmable gate array, FPGA）的红外光谱信号采集系统实现方案,采用Altera公司的EP2C35系列的FPGA为控制核心,完成多路模拟开关切换、A/D转换、数据存取等功能,实现对64路红外光谱信号的采集。同时针对光谱仪输出的微弱直流信号,设计信号调理电路来抑制噪声,最后通过串口通信将数据传给上位机;简介了各功能模块的实现方案,并进行了实验验证,结果表明该系统的精度和可靠性高,并且最小可检测到0.23 μV的微弱直流信号,实际信噪比达到45 dB。     

Analysis of new methods for broadcasting digital data to mobileterminals over an FM-channel

Two new methods using an FM-radio channel for transmission of digital data to mobile terminals are examined: 1. A modification of the radio data system (RDS). In RDS, additional digital information is multiplexed with a stereo sound signal. A new system is suggested where the data signal can be multiplexed with a mono audio signal. This causes extension to the bandwidth available for the data signal, and therefore the RDS bitrate can be increased. Error calculations are performed both for the original RDS system and for the new system. 2. Orthogonal frequency division multiplexing (OFDM). OFDM is used in the digital audio broadcasting system (DAB), which is designed to transmit digital audio in the FM band. In OFDM a signal is divided over a large number of 2- or 4-PSK modulated orthogonal subcarriers. The subcarriers of 6 different programmes are multiplexed in one beam to reduce the effects of frequency selectivity of the transmission channel. A new system based on OFDM is proposed, in which the carriers of each programme are transmitted in one FM-channel with a bandwidth of 200 kHz instead of multiplexed with the carriers of other programmes. Error calculations are performed for the subcarriers used in the OFDM modulation method     

160 Gbit/s OTDM signal transmission over 26 km photonic crystal fibre

A 160 Gbit/s (=10 Gbit/s X 16) optical time-division multiplexing (OTDM) signal is successfully transmitted over a 26 km-long photonic crystal fibre (PCF). The transmission induced signal pulse broadening is suppressed to only 0.2 ps (from 2.1 to 2.3 ps) because the fabricated PCF has low polarisation-mode dispersion (PMD) of 0.1 ps/km^1/2, and the total chromatic dispersion of the transmission line is suppressed to 0.015 ps/nm by using a dispersion-compensation fibre. The transmitted signal is demultiplexed using four-wave mixing in a 100 mlong dispersion shifted fibre, where a phase modulation-based 10 GHz pump pulse source is newly adopted.     

防离子反馈MCP噪声因子测试与分析

噪声因子是输入信噪比和输出信噪比的比值,能够反映微通道板的噪声特性,是影响微光像增强器信噪比的主要因素。为探寻降低微光像增强器中防离子反馈微通道板噪声因子的技术途径,根据微通道板噪声因子定义和测试原理,构建了防离子反馈微通道板噪声因子测试系统。由于防离子反馈微通道板的输入面镀覆有一层薄膜,其对微通道板的噪声因子有较大影响。因此,利用噪声因子测试系统重点测试了有、无防离子反馈膜以及不同材料、不同孔径、不同输入电子能量、不同微通道板作电压条件下的微通道板噪声因子,获得了微通道板噪声因子与输入电子能量、微通道板电压之间的关系,为降低防离子反馈微通道板噪声提供了有效的技术指导。     

Guided-wave planar optical interconnects using highly multiplexedpolymer waveguide holograms

An intraplanar interconnection scheme using substrate guided modes in conjunction with a highly multiplexed waveguide volume hologram is proposed. Acoustooptically addressed 1-to-50 passive and 1-to-2-to-100 reconfigurable interconnections with a fan-out diffraction efficiency of 55% at 514-nm wavelength are demonstrated. A coordinate transformation converts the 3-D diffraction problem into a 2-D one, which significantly simplifies the theoretical calculation. Intraplane massive fan-out optical interconnection using substrate guided mode provides both collinear and coplanar fan-out capability for data and clock signals. Colinearity of signal distribution allows the 2-D input signal array to be processes. The laminated waveguide device containing a highly multiplexed dichromated gelatin (DCG) hologram has been evaluated     

Study of BER of 64-QAM signal and OMI-window of feasible operationin analog/digital hybrid SCM transmission systems

In an analog/digital hybrid subcarrier multiplexed (SCM) transmission, carriers have generally been substituted for transmission signals such as AM vestigal sideband (AM-VSB) AM signals and M-QAM signals to evaluate transmission quality. In practical hybrid SCM, however, carriers are modulated by video signals or digital data, and the amplitude of a multiplexed signal composed of these modulation signals is more compressed than that of the carriers. This causes a decrease in the frequency of clipping of the multiplexed signal at the laser threshold. Consequently, the BER of the M-QAM signal in a practical hybrid SCM is lower than that of the experimental results for the same optical modulation index (OMI). However, it is difficult to prepare many practical modulation signals for experiments in a laboratory. Therefore, there is demand for a bit error rate (BER) analysis method for a multiplexed signal that includes the modulation signals needed to sufficiently evaluate the BER and determine the optimum OMI in a practical hybrid SCM. In this paper, we describe such a BER analysis method that can effectively estimate the BER in a practical hybrid SCM. In practical systems, the BER was greatly improved over the BER of a multiplexed signal of carriers. Furthermore, BER degradations due to clipping can be neglected for the AM signals in setting a practical OMI range. We used this analysis method to study the effective OMI range of AM and M-QAM signals. By assuming modulation signals, the OMI range is enlarged and, significantly, the OMI of an AM signal becomes suitable for setting practical values in AM-SCM transmission. This OMI range is more practical than those of former studies     

Ultracompact microring laser-based optical-add multiplexer

A highly compact and scalable microring-laser-based optical-add multiplexer is presented for wavelength division multiplexed bus networks. The output of a 40 mum-radius microring laser is vertically coupled to a passive waveguide bus and the chip is subsequently mounted in a butterfly package with fibre pigtailing at both input and output. In the first such experiment with a microring-based module, a wavelength channel is added into a wavelength multiplexed fibre-optic link with negligible power penalty. Successful transmission of a 2lambda x 2.5 Gbit/s signal over 25 km is demonstrated for a 0.9 nm channel spacing.     

偏振复用QPSK相干光数字通信系统实验研究

建立了偏振复用正交相移键控(QPSK)传输及相干检测的数字通信实验系统,并分析系统的性能。40Gbit/s的偏振复用QPSK信号在单模光纤(SMF)中传输了100km;信号光与本振光在接收端进行混频并下变频,最后用数字信号处理(DSP)算法对接收信号离线处理。比较了光纤传输前后不同的光信噪比(OSNR)下的误码率(BER),实验结果表明,所使用的DSP算法能克服光纤信道对信号的主要损伤,对高速的相干检测信号进行有效的恢复。     

FM microwave multiplexed broad-band distribution systems using Er3+ fiber amplifiers and preamplifiers

The use of an Er³⁺ fiber preamplifier for microwave multiplexed systems and the use of an inline Er³⁺ amplifier in microwave multiplexed systems for signal distribution are reported. The improvement in receiver sensitivity as a preamplifier, without optical filtering, was 9 dB. No power penalty due to amplified spontaneous emission was found when the amplifier was used in a 30-channel signal distribution system     

Fiber Optic Intermodulation Distortion

In analog frequency-division multiplexed fiber optic systems, laser nonlinearities transfer energy between the different carriers, resulting in intermodulation distortion and interference. A third-order polynomial without memory is used to model the nonlinearity. The FM frequency-division multiplexed (FM/FDM) signal consists of a set of FM carriers at frequencies.N_{omega 0}, whereN = L, L + 1, L +2, ... , M. The video distortion introduced by the nonlinearity is determined for various types of second- and third-order intermodulation terms. The intermodulation distortion frequency spectrum is determined for FM signals with assumed Gaussian spectra.     

Orthogonally multiplexed orthogonal amplitude modulation family

A family of coherent orthogonally multiplexed orthogonally amplitude-modulated (OMOAM) signals is presented. The OMOAM signal is constituted by orthogonally multiplexing AI component signals, each constructed by a data-chosen group of L orthogonal pulse-amplitude-modulated basis signals. A generalized signal format is proposed to model the OMOAM signal in a unified way that the family contains not only classical orthogonally multiplexed modulations as special embodiments, but also a multitude of new modulations. A generalized optimum receiver for coherently demodulating OMOAM signals is developed and analyzed in terms of the bit error probability for the additive white Gaussian noise channel. The spectral characteristics of the OMOAM signals constructed from various time-limited and band-limited basis sets are studied in terms or the fractional out-of-band power containment. Several general trends of error and spectral performance characteristics are exploited