Advanced electronics for the CTF MEG system.
Advanced electronics for the CTF MEG system.
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CTF MEG 系统的先进电子设备。
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
A. A. Fife
中科院分区：
文献类型：
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作者：
J. McCubbin;J. Vrba;P. Spear;D. McKenzie;R. Willis;R. Loewen;Stephen E. Robinson;A. A. Fife
随着数据采集电子系统和主机之间的计算机处理集群的引入，CTF MEG系统的发展得到了推进。快速处理器、内存和网络接口的出现使得这种创新对于高采样率的大数据流是可行的。我们已经实现了包括抗混叠滤波器、采样率抽取、更高梯度平衡、串扰校正和可选滤波器在内的任务，该任务由4个双英特尔至强处理器组成，可在多达275通道的MEG系统上以12 kHz采样率运行。该架构可通过额外的处理器进行扩展，以实现高级处理任务，例如，连续头部定位/运动校正、可选显示滤波器、相干计算或实时合成通道（通过波束形成器）。我们还描述了电子配置升级，以提供操作员控制台访问外围接口功能，如模拟信号和触发I/O。这样就可以远程定位噪声较大的电子机柜，并安装带有门的机柜，以改善电磁干扰屏蔽。最后，我们介绍了CTF 275通道MEG系统的最新性能结果，包括通过应用自适应波束形成技术（SAM）增强的非屏蔽SEF（正中神经电刺激）测量，该技术允许识别非平均信号中的标称20毫秒响应。
Development of the CTF MEG system has been advanced with the introduction of a computer processing cluster between the data acquisition electronics and the host computer. The advent of fast processors, memory, and network interfaces has made this innovation feasible for large data streams at high sampling rates. We have implemented tasks including anti-alias filter, sample rate decimation, higher gradient balancing, crosstalk correction, and optional filters with a cluster consisting of 4 dual Intel Xeon processors operating on up to 275 channel MEG systems at 12 kHz sample rate. The architecture is expandable with additional processors to implement advanced processing tasks which may include e.g., continuous head localization/motion correction, optional display filters, coherence calculations, or real time synthetic channels (via beamformer). We also describe an electronics configuration upgrade to provide operator console access to the peripheral interface features such as analog signal and trigger I/O. This allows remote location of the acoustically noisy electronics cabinet and fitting of the cabinet with doors for improved EMI shielding. Finally, we present the latest performance results available for the CTF 275 channel MEG system including an unshielded SEF (median nerve electrical stimulation) measurement enhanced by application of an adaptive beamformer technique (SAM) which allows recognition of the nominal 20-ms response in the unaveraged signal.