1/2-inch cassette VTR for baseband HDTV signal recording

Technical details are reported for a 1/2-inch cassette videotape recorder (VTR) developed for recording the baseband high-definition TV (HDTV) signal. A recording time of 63 min was achieved by using metal-particle tape and laminated amorphous video heads. The frequency bandwidths used for luminance and chrominance signals were 20 and 7 MHz, respectively. A novel two-channel, three-segment recording method was developed for the purpose. Four-channel digital audio recording with a sampling frequency of 48 kHz and 16-b linear quantization was used. The digital audio signal was recorded on the overlapped area succeeding to the video track by using the same heads used for video recording     

High-resolution ultrasound transverse flow measurement

A method for measuring the transverse component of flow velocity with high spatial resolution is reported. This technique is based on recording and cross-correlation of the signals scattered from two adjacent foci, produced by a newly developed two-beam acoustic lens. Experiments at 4.5 MHz are described and illustrated by results obtained from flow in the range 50-100 cm/s     

A broad-bandwidth mixed analog/digital integrated circuit for themeasurement of complex impedance

A broad-bandwidth measuring system for complex impedances is presented. The measuring principle, based on synchronous detection, is worked out mathematically. The final circuit is realized as a mixed analog/digital BiCMOS integrated circuit. The output of the IC is a modulated 100-Hz frequency and RS232. The phase accuracy of the system is 0.07° at 20 MHz and is mainly determined by the parameter deviation of transistors that share the same IC. The circuit enables measurement of a capacitance of up to 100 pF with an accuracy of ±1 pF, in parallel with a conductance of up to 100 mS. Apart from the impedance measuring circuit, the IC can process signals from other sensors, such as for temperature or pH. The design criteria for the IC are derived from the primary application in a sensor for water content and ionic concentration measurements in soil or other agricultural substrates     

Continuous recording instrument for RF-exposure measurements in FM/TV broadcasting towers

A continuously recording exposure meter has been developed for radio-frequency (RF) hazard measurements in FM/TV broadcasting towers for the frequency range 47-790 MHz. The instrument consists of an electrically-small dipole, loop probes and recording electronics. The dipole and loop are attached to the safety helmet; their distance from the head is approximately 7 cm. The dipole and loop respond to the tangential E field and radial H field, respectively. The error due to body proximity and one-dimensionality is 1 to 2 dB at 100 MHz and 2 to 3 dB at 200 MHz (for average power density measurements) if the probes move continuously and the measurement period is sufficiently long. Measurements in Finnish FM/TV towers showed that the average power density inside the tower increases with increasing power and decreasing antenna surface area. The highest levels have been found near UHF and FM antennas. For the FM band (100 MHz) the average H field exposures exceed the new ANSI standard value 10 W/m2, but remain in most cases below 100 W/m2. Local maxima may exceed 300 W/m2.     

一种数字控制电感测量仪的设计与实现

设计了一个以芯片STM32F407ZGT6为控制核心的数字式电感测量仪,可以对正弦信号源、电感Q值以及电感值实现精确测量。系统硬件电路主要由电源供电电路、信号产生电路、信号调理、测量电路、数据采集与处理以及人机交互等模块组成,其中信号调理电路采用高速运放进行放大和阻抗变换,调节信号幅度的同时保证各级的输入输出阻抗,以达到最高的测量精度。测量电路采用谐振法测量回路谐振频率,然后用伏安法测量可变电容当前值,再通过谐振频率和电容值计算得到被测电感的Q值和电感值。最后经过测试,系统实现了输出范围达50～40MHz 的正弦信号源,测量误差优于0.1%,并且对电感Q值和电感值的测量误差均小于3%。     

单频激光宽频段频率和强度噪声测量技术

报道了一种mHz至MHz宽频段激光噪声的规范测量技术。通过研制基于迈克耳孙光纤干涉仪的相关延时自外差频率噪声测量装置和具有定标功能的光外差拍频测量装置,结合频谱分析仪和快速傅里叶变换分析仪等标准仪器,规范地测量出了单频激光在mHz至MHz宽频段内的频率和强度噪声特性,并验证了测量结果的准确性。该测量技术有望应用于引力波探测和精密测量等应用中的激光噪声评估。     

基于像面数字全息术的中药饮片细胞定量成像技术研究

细胞三维定量成像为中药饮片显微鉴别提供了新方法。为了提高数字全息显微成像质量,采用理论分析与实验验证相结合的方法,对球面参考光像面数字全息显微术的记录和再现过程进行了研究,提出了利用标准分辨率测试板对系统放大倍数、物距等参数进行标定的方法;并利用实验结果对两种常见的相位解包裹方法进行了对比。结果表明:球面参考光像面数字全息图不仅具有较高的信息容量,而且再现过程非常简单,还可以在记录过程中实时观察被记录样品的情况,并选择恰当的被记录区域。利用美国空军分辨率测试板的强度再现像就可以对全息成像系统的放大倍数等参数进行精确标定;利用基于横向剪切的最小二乘解包裹方法可以得到具有较大纵深细胞的准确相位;采取边缘识别技术,可以提高细胞再现像显示效果。     

数字阵列雷达收发组件自动测试技术研究与实现

针对数字阵列雷达收发组件数量众多,传统测量方法过程繁琐、无法测量出多通道间指标的实际情况,给出了多通道DAM模块自动测试系统的设计方法,应用基于SOPC的网络数据传输技术,基于DDR2的高速数据缓存技术和虚拟仪器技术等,较好地解决了多通道接收机指标快速测试的难题,具有自动测试与校准、测量数据准确、测试效率高等特点,取得...     

Low cost video scaler and gray scale integrator

A hybrid digital/analog device capable of making high-resolution linear and area measurements from a standard monochromatic video image is described. The device is capable of dynamic as well as static data acquisition when used in conjunction with standard NTSC video recording equipment. Digital output allows for computer interfacing. Linear dimensions are obtained by electronically superimposing two horizontal and two vertical scaling lines on a video monitor. Each linear dimension has an eight-bit resolution and is displayed on the front panel with seven segment LEDs. Eight-bit, digital-to-analog converters are also used to provide analog outputs. A measurement of the temporal deformation pattern of the accessory capsule surrounding a mechanoreceptor (Pacinian corpuscles) in response to vibratory displacements is demonstrated. Area measurements are obtained via a window comparator, a 6 MHz clock, and a 16-bit digital-to-analog converter. Data is only valid within the zone set by the scaling lines, allowing data regions to be isolated from noise, etc. The 16-bit digital signal measuring the area of interest is then converted for analog output. The measurement of the consensual pupillary reflex in response to full-field illumination (Ganzfeld) is given as an example     

检测LCM对数字万用表准确度的要求

测量是质量检验工作的重要组成部分。通过测量可以确定被测量的大小,为质量检验、合格判定提供数据支持。用于测量的测量仪器在其中扮演着重要角色。没有它测量无法进行,、但有了它,测量也不见得就可以进行。因为测量仪器有分辨率、准确度之分,不恰当的分辨率、准确度,同样无法准确测量被测量的大小,如果用于测量,反而会因为误测误导使用者作出错误的判定。在液晶显示行业,用于检测液晶显示模组（LCM）的数字万用表,如果选用不当,同样有此隐患。因此．选用合适的数字万用表用于LCM检测显得尤其重要。本文侧重分析不同准确度万用表对测量结果的影响,并根据目前LCM行业内对产品设计公差的要求．推算在驱动电压、功耗电流、内阻的检测上对数字万用表准确度的要求．为LCM行业内数字万用表的选用提供参考。     

中频脉中压缩信号数字化直接产生技术研究

该文提出了一种脉冲压缩中频信号数字化产生方法及硬件实现方案,对其中的一些关键问题做出了定量分析;在此基础上完成了一套波形产生器,可产生6种中频15MHz、带宽1MHz、时宽等于或小于300s的线性调频、非线性调频信号。测试表明其谐波与杂散均优于-68dB,完全达到工程应用要求。     

数字化精密测距技术的研究

精密测距（DME/P）无线电导航系统与微波着陆系统配合,为进场飞机提供精密进场着陆引导。基于FPGA＋DSP硬件平台,提出了数字中频处理DME/P的一种实现方法,详细分析了数字化DME/P采用的技术：数字中频解调技术、DAC检测技术、信号识别和搜索技术以及α-β滤波技术。通过飞机实际飞行试验,该方法能够完全满足DME/P功能的性能指标,为DME/P设备的小型化和数字化提供了可靠的科学依据。     

An Integrated Patch-Clamp Amplifier in Silicon-on-Sapphire CMOS

We designed and tested an integrated patch-clamp amplifier capable of recording from pico to tens of microamperes of current. The high-dynamic range of seven decades and the picoampere sensitivity of the instrument was targeted to whole-cell patch-clamp recordings. The prototype was fabricated on a 0.5-mum silicon-on-sapphire process. The device employs an integrating headstage with a pulse frequency modulated output, ranging from 3 Hz to 10 MHz. A digital interface produces a 16-bit output conversion of the input currents. We report on electronic characterization of the fabricated device, dynamic performance, and examples of measurements on biological cells for patch-clamp applications. The device will be used in an advanced planar high-throughput patch-clamp screening system for testing medicines     

Semidigital multiplication by discrete convolution using surfaceacoustic wave (SAW) devices

The computation of the product of two digital numbers by discrete convolution by a surface acoustic wave (SAW) convolver is described. The principal limitations of the method are discussed as well as realistic performance numbers that can be achieved by using available SAW device technology. The multiplication is done by convolving the 2-b streams that represent two digital input operands in a SAW convolver at a rate of 100 MHz. The convolver output is the product in mixed binary representation. It consists of one analog value per digit with a resolution of 0.5%. These values are digitized at a rate of 200 MHz by an 8-b flash analog-to-digital converter and added up to form the digital result. It is shown that such a device has a very high computing power that can be adapted to special applications. One extreme is the multiplication of 256-b integer numbers, corresponding to a dynamic range of 1:10⁷⁷, at a rate of 0.2 MIPS. The other extreme is the computation of matrix products where computing speeds of 12000 MIPS can be achieved for 8-b operands, as required, for example, in image filtering applications     

全极化微波辐射计系统中高速数字相关器设计

海面风场直接影响大气与大洋环流相互作用,是研究海流运动规律的必要条件.全极化微波辐射计是一种用于海洋表面风场测量的新型被动微波遥感器.数字相关器是全极化辐射计的核心部件.文中详细介绍了一种新型数字相关器的设计和实现.两片高速A/D转换器采样四路信号并通过XILINX公司新一代的FPGA-Vertex5作相关运算.同时本...     

Digital multiphase clock/pattern generator

In telecommunications systems, the commonly used method to generate clocks is based on phase-locked loop or delay-locked loop related frequency synthesis. In this paper, we address a method of digital multiphase clock/pattern generation (MPCG) to generate a system clock or pulse pattern vector when a multiphase clock is available. The advantages of the multiphase clock method are: (a) the design method is digital; (b) the working frequency range is very wide; and (c) the sensitivity to noise is less than analog methods. Different approaches to implement the basic blocks in MPCG are described. A design example implemented in BiCMOS uses eight clock phases at 622 MHz obtained by dividing a 5-GHz clock to generate a clock at 622 MHz×32/53=376 MHz. By such a method, we can generate a pulse pattern vector as well. The maximum time resolution is equal to half of the phase difference. A low power solution is achieved without loss of circuit speed     

智能化交流电参数综合测量仪

本文介绍了一种单相或三相周期形交流信号电参数综合测量仪。仪器中采用了逐点积算和隔周期延迟采样等数据处理方法，不仅可以对AC信号的电参数进行综合测量，还可使仪器的电路结构大为简化。     

多功能数字测试仪的设计与实现

为把数字万用表、绝缘电阻表、漏电开关测试仪等三种功能的测量仪器,合并为一种新型手持式测量仪表。采用专用集成电路ES51921和高性能微控制器MSP430F2111及外部扩展电路、液晶显示器（LCD）等组成,将多功能测试仪设计成具有多功能、智能化的特点和显示直观、读数精准、功能完善、耗电省、体积小、易于携带等优点。该多功能测试仪经测试符合相关技术标准。     

基于欠采样的激光测距数字鉴相方法

欠采样方法为实现全数字化接收、降低激光测距系统复杂性提供了有效途径。针对传统欠采样数字同步解调法引入干扰大的缺点,为提高系统的测量精度,提出了欠采样频域谱分析鉴相法。方法基于Nyquist采样谱分析鉴相思想,通过对欠采样后搬移到低频的频谱成分进行分析获取相位信息实现鉴相,在抵抗干扰方面具有较好的性能。在加入信噪比40 dB、杂散频率、0.1 MHz频率偏移、2次谐波的综合影响因素后的仿真结果表明,在1 MHz测距速率下,欠采样谱分析鉴相法精度为0.13,调制频率80 MHz时测距精度为0.68 mm,优于传统的欠采样数字同步解调法。因此,欠采样谱分析法更适用于高速、高精度的数字化相位差测量,提出的实现方案具有实际意义。     

基于陷波器的数字失真度仪设计

各种失真度测试仪已经在电子、电力、通信等领域得到广泛的应用,但普遍存在仪器价格较高、操作繁琐、测量精度不高的缺点.文中在研究基于数字陷波滤波技术进行失真度测量的基础上,通过虚拟仪器的方式实现了数字失真度仪的设计,有效地克服了传统数字失真度测量方法中频谱泄漏对失真度测量的影响,降低了成本,具有较高的测量精度.