A 128-Channel Simultaneously Sampling Data Acquisition System for the Diagnostic Complex of Experimental Plasma Facilities

The simultaneously sampling data acquisition system contains 16 eight-channel modules, which record the shapes of single pulse signals, and the controller module of the system bus of the Eurocrate, which interacts with the basic computer of the diagnostic complex via an Ethernet-FX communication line supported by TCP/IP protocols. The recording modules are based on 12-bit analog-to-digital converters (ADC). The ADC samples are fixed in buffer storage units with a capacity of up to 1 Mword/channel. The current amplitudes of the input signals are measured simultaneously in all recording channels with a time jitter of 3 ns. The maximum sampling frequency is below 4 MHz.     

A Multichannel System of Galvanically Insulated Single Pulse Shape Recorders

A data acquisition system containing up to four multichannel galvanically insulated modules capable of recording the shapes of single pulse signals is described. The recording modules are built on 12-bit ADC with sampling frequencies of 0.5 and 40 MHz and connected by serial fiber-optic communication lines to an interface board, which connects them to an ISA bus. The system is intended for the multichannel diagnostic sections of plasma setups.     

A Controller for the Study of Fast Processes

A controller has been developed that forms a sequence of rectangular RF pulses, performs a fast synchronous (synchronized with the pulse sequence) analog-to-digital (AD) conversion of the electric signals, writes digital data in to the RAM, and transmits these data to the ISA (IBM PC) bus. The program control of the position and duration of the formed pulses (with a step of 20 ns), as well as of the carrier frequency of RF pulses (up to 25 MHz with a step of 0.01 Hz), is ensured. The fast parameters of the AD conversion are the following: the digit capacity is eight bit and the sampling frequency is 50 MHz.     

A system for measuring the electromagnetic characteristics of the KTM tokamak

A system for measuring electromagnetic characteristics of the KTM tokamak physical setup with the magnetic thermal insulation of plasmas includes primary signal-processing modules, interface converters, and data recording unit. When the input signal varies from ?300 to +300 V in a 0-to 500-kHz frequency band, the reduced error of channels measuring signals from sensors is 1.5%. The system uses a channel-by-channel galvanic decoupling for protecting the equipment. The throughput of the digital data transmission channels is 100 Mbit/s per channel. The system is intended for operation with 160 measuring channels.     

A Data Acquisition System for Very-Long-Baseline Interferometers

A data-acquisition system designed for very-long-baseline interferometers is connected to the outputs of cryoelectronic radio astronomy receivers, selects signals in specified frequency bands, and converts them into digital data flows for their recording or transmission through telecommunication channels. The system has two inputs and may contain from two to eight base-band converters with an intermediate frequency tuning range of 100–1000 MHz with a 10-kHz step. These converters transform input signals into video frequencies (up to 16 MHz) and separate signals of the upper and lower side bands with an image rejection of >23 dB. The distortions and loss in the phase coherence of the received noise signals are minimized thanks to the equalizing of the amplitude and phase responses of the amplifiers and selectors, and the good spectral characteristics of the local oscillators of the base-band converters. The data-acquisition system is controlled by a PC or the Mark IV Field System program (now used internationally in the pursuit of radio interferometry), which is installed in the radio telescope's central computer using an RS-232 interface. The prototype of such a system is used as standard equipment for conducting observations on the Svetloye–Zelenchukskaya radio interferometer. The first lot of such systems for the development of a network of radio interferometers has been produced.     

A soft and hardware complex for recording and processing of acoustic emission signals and for location and identification of their sources

A soft and hardware complex designed for recording and processing acoustic emission (AE) signals in real time is described. The hardware part of the complex includes a computer with PCI connectors, four-channel parallel-reading analog-to-digital converters (ADCs), preamplifiers, and receiving converters. The software part of the complex is used to record and save in all recording channels the full shape of signals with a preset sampling frequency of up to 20 MHz, locate, identify, and classify AE sources in real time. It differs from analogs in the capability of saving the full shape of AE signals for further analysis and processing, in use of commercially produced ADCs, and in real-time data processing and classifying of AE sources.     

A Recorder of Broadband Signals with Accelerated Data Output

An 8-bit recorder with a sampling frequency of 200 MHz and maximum frequency band of processed signals of 150 MHz is described. The device is interfaced with a computer PCI bus and is designed for the statistical investigation of broadband signals. Results on the separation of small signals from noise using this recorder are presented.     

Use of parallel channels in wideband signal recorders

A wideband signal recorder in which four parallel analog-digital channels are used for increasing the sampling frequency is described. The recorder consists of four analog subchannels, a synchronization unit, four analog-to-digital converters, a controller for a programmable logic array, and a USB interface. The following characteristics are attained: the frequency band is 200 MHz, the maximum sampling frequency is 1 GHz, the memory is 16 kbyte, the input-signal range is ±(0.5, 1, and 2) V, and the input is matched (50 Ω). Physically, the recorder is the external (to the USB bus) device of a computer.     

空间光学遥感器的多光谱TDI CCD信号检测及仿真

为了实现采用高性能多光谱TDI CCD 对空间光学遥感系统的合理设计及应用,提出了对CCD控制信号的高速并行实时检测方法和视频图像连续输出的仿真设计方案。利用CCD行读出及转移的200µs周期,对48路控制CCD驱动信号和31路直流偏置信号进行并行实时逻辑分析及检测。同时,把预制的CCD模拟图像,从磁盘阵列经PCI-X及LVDS总线高速传输到由FPGA、D/A、放大和滤波电路组成的视频图像生成系统,实现可连续、实时输出各种模拟测试图像。实验结果表明,可同时输出3路6MHz频率的彩色图像和8路12MHz频率的全色图像象素信号波形。象素信号基准电压8V;振荡幅值0～1.7V。有效采样时间和信号稳定度均满足成像电路的仿真测试要求。     

具有图形组态功能的传感器阵列测试系统

基于虚拟仪器的思想,研究开发了一套传感器阵列测试系统,用于对各种高速时变场的工程测量。系统包括64个最高采样频率为1MHz、转换精度为3位的模拟通道,以及4个最高采样频率为15.625kHz、转换精度为12位的模拟通道;系统软件采用观察者对象行为型设计模式,通过建立动态图元与实验数据之间的松散耦合实现了图形组态功能。系统与二维光电传感器阵列及电压、电流传感器配合,运用于低压开关开断过程特征参数的测量,直观地得到了低压开关开断过程中电弧的运动情况及电流、电压曲线,并动态仿真了这些特征参数之间随时间变化的相互影响关系。     

A Data Stream Converter for a Radio Telescope with a Wideband-Signal Digital Recording System

A data-stream converter makes it possible to connect a radio telescope with wideband (512 MHz) signal-recording channels to active very-long-baseline interferometers using multichannel recording systems for narrowband (16 or 8 MHz) signals. A digital converter based on a field programmed gate array (FPGA) selects and formats up to 16 narrowband signals.     

Direct detection and time-locked subsampling applied to pulsed electron paramagnetic resonance imaging

The application of direct time-locked subsampling (TLSS) to Fourier transform electron paramagnetic resonance (FT-EPR) spectroscopy at radio frequencies (rf) is described. With conventional FT-EPR spectroscopy, the high Larmor frequencies (L(f)) often necessitate the use of intermediate frequency (IF) stages to down convert the received free induction decay (FID) signal to a frequency that can be acquired with common data acquisition technology. However, our research focuses on in vivo studies, and consequently utilizes a FT-EPR system with a L(f) of 300 MHz. This relatively low frequency L(f), in conjunction with the advent of bandpass sampling analog-to-digital conversion and signal processing technologies, has enabled us to omit the IF stage in our FT-EPR system. With this in mind, TLSS techniques have been developed to directly sample the 300 MHz FID signal at a sampling rate of 80 MHz providing a signal bandwidth of 20 MHz. The required modifications to the data acquisition and processing system specific to this application are described. Custom software developed to control the EPR system setup, acquire the signals, and post process the data, is outlined. Data was acquired applying both coherent averaging and stochastic excitation sequences. The results of these experiments demonstrate digital down conversion of the 300 MHz FID signal to quadrature baseband. Direct FID TLSS eliminates many noise sources common in EPR systems employing traditional analog receiver techniques, such as the IF mixer stage in single channel systems, and the quadrature baseband mixer stage in dual channel systems.     

Spectral-selective radiometers with bandwidths of up to 1 GHz

Spectral-selective radiometers, ensuring high-accuracy measurements in continuum under exposure to narrow-band radio-interferences and detection of radio-wave radiations in spectral lines, are described. Two parallel channels of the radiometer simultaneously receive signals of two polarizations or signals of two wave bands. The channels of the radiometer installed at the Badary observatory operate in frequency bands of up to 32 MHz and have a resolution of 62.5 kHz, if the reception band is at maximum. The channels of the radiometer at the Svetloe observatory have reception bands of 1024 or 512 MHz and a resolution of 1.0 or 0.5 MHz, respectively.     

Digitization of Waveforms from Photosensors of the DANSS Detector

The detection equipment of the DANSS setup includes 2500 silicon photomultipliers and approximately 100 photomultiplier tubes (PMTs). The system of data acquisition from these photosensors is based on waveform digitization, with which it is possible to simultaneously obtain both amplitude and timing information. The modules of waveform digitizers (WFDs) are made to the VME standard and allow parallel digitization of 64 differential signals at a frequency of 125 MHz with a 12-bit amplitude resolution. The programmable logic of the WFDs provides production of the system trigger based on the analysis of the PMT signals and its propagation without any additional hardware. Owing to the extremely low analog noise, it is possible to use the full dynamic range of the digitization. These WFD modules are superior to other similar modules in the throughput and may find wide application to perform similar tasks of waveform digitization.     

Frequency measurement technique based on frequency conversion

To measure the signals with high freq u ency(>500 MHz),a sampling frequency down conversion method is introduced.This pa per analyzes the intermodulation signals and figures out the relationship betwee n the intermodulation signal and intermediate frequenc y signal.Based on the frequency conversion technology,an exclusion algorithm i s proposed a nd the actual implementation of the algorithm is given.The application resu lts show that the exclusion algorithm can identify the intermodulation signal exactly and eliminate the bad influence on the frequency measurement.     

高速数据采集系统的设计

本文介绍了一种包括数据采集硬件及数据处理软件的高速数据采集系统。硬件部分为高速单片机DSC875 2 0控制的高速数据采集卡 ,通过ISA总线与工控机连结 ,主要采用了ISA总线技术、I/O接口技术和中断技术。用DELPHI语言编写的软件系统对数据进行分析和处理。本系统的特点在于该系统在单片机的控制下实现高速数据采集 ,采样频率可达 1～ 2MHz。该系统可靠性高 ,抗干扰能力强 ,造价低廉     

Multichannel control system for an acousto-optical modulator of laser radiation based on direct digital synthesis of frequencies

A module of control of an acousto-optical modulator of laser radiation in a multifrequency mode on the basis of a multichannel synthesizer with direct digital synthesis of frequencies is described. Specific features of system operation during multichannel laser recording with controlled amplitude, phase, and frequency of the channels with automatic calibration of intensity in each channel are considered. Application of the system in a photoplotter for producing photomasks of printed circuit boards makes it possible to increase the resolution of the device and to improve stability and reproducibility of recording.     

A digital signal conversion system for astronomy radio interferometers with small antennas

Results of designing a digital signal conversion system for radio interferometers with small-diameter (up to 12 m) antennas are presented. The system contains four digital signal conversion channels with 500-MHz bandwidths. The output data stream rate in the VDIF format is 2048 Mbit/s per channel, and the cumulative output data flow is 8192 Mbit/s. The observation data flows arrive at the signal recording buffer unit and can be transmitted from there via a 10G Ethernet interface to a correlator in near-real time.     

The Prospects for Using High-Speed Analog-to-Digital Converters to Analyze the Signals of Ionizing-Radiation Detectors

The potential advantages of recording digital signals from ionizing-radiation detectors are considered. State-of-the-art high-speed analog-to-digital converters operating at sampling frequencies of 400 MHz (2.5 ns) and higher with a buffer storage of up to 4 Gbyte and a data-input rate of up to 400 Mbyte/s are capable of recording continuous pulse sequences with a throughput of >10⁷ pulse/s in less than 10 s. In contrast to standard recording methods in which overlapping pulses are truncated, the recording of complete signal flows allows one to detect and resolve overlapping pulses quite well, provided they arrive within 20–40 ns of one another.     

一种新型宽带频率计

在宽带频率范围内首度将预分频法、相检测频法和多周期同步法相结合,在2 Hz～6 GHz的范围内实现了较高精度的频率测量.频率计模块采用高、中、低3个输入通道,功能电路及控制电路在复杂可编程逻辑器件CPLD内完成.该频率计模块基于PXI总线,采用虚拟仪器技术设计了仪器操作软面板.经过仿真和实验,验证了该测量方法的正确性.