Patent Application
20090234603
Vector network analyzers (VNAs), spectrum analyzers, oscilloscopes and other electrical measurement instruments represent some of the standard test tools for RF and microwave engineers. For example, the capability of VNAs to provide error-corrected amplitude and phase responses of active and passive components makes them invaluable in the research lab as well as on the production floor. While such instruments have been associated classically with racks of equipment in a testing lab, portable versions of them with reduced capability have been proliferating recently among field maintenance crews for on-site testing of antenna installations, cell sites, etc. This increasing interest has created a need to improve on the power efficiency and/or performance of portable measurement instruments so as to enhance their usability and reliability in the field.
Graphical processing units (GPUs) were originally developed as dedicated graphics rendering devices for use as adjuncts to central processing units (CPUs). GPUs improve manipulation and display of computer graphics by performing calculations that accelerate CPU and memory-intensive tasks such as texture mapping, polygon rendering, and translating vertices into different coordinate systems. A highly parallel structure provides GPUs with floating-point performance that exceeds floating-point performance of current CPUs.
Exceptional floating-point performance enables use of GPUs for executing a range of complex algorithms. As a result, GPUs are finding increased usage in non-graphics related applications including in computationally intensive areas such as numerical electromagnetics, fluid mechanics, fast Fourier transforms (FFT), and the solution to dense systems of linear equations. Enhanced performance in such applications can be attributed both to the massively multi-core nature of current GPUs and to a larger memory bandwidth relative to current CPUs. To facilitate such usage, NVIDIA, Corp. has made a programming interface available allowing programmers to harness the floating-point computational speed of GPUs manufactured by NVIDIA, Corp. In addition to the programming interface, two high-level libraries are included that can be used for performing FFTs as well as common vector and matrix operations. GPUs produced by NVIDIA and other manufacturers, such as ATI Technologies, a subsidiary of Advanced Micro Devices, Inc., may also be accessed for non-graphical or general purpose computations using a generic compiler, such as BrookGPU, a compiler and runtime implementation of the Brook stream programming language created by the Stanford University Graphics Lab.
Electrical measurement instruments make use of mathematical operations such as FFTs, Hilbert transforms, windowing, convolution and deconvolution, and operations on vectors and matrices at various stages during instrument calibration, post-processing of data, or both. Referring to
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In addition to increased floating-point performance, GPUs exhibit improved power-consumption-to-performance ratio over CPUs, with the power consumption of a GPU being less than that of a CPU for achieving similar computational performance. Reduced power consumption can benefit battery-operated measurement instruments. By redirecting data for post-processing to the GPU 212, the electrical measurement instrument can reduce overall power consumption for a given set of results, prolonging battery life. It may be desired that the electrical measurement instrument divide measurement data between the CPU and the GPU for post-processing to reduce computation time. Measurement data processed using algorithms for which stream processing is advantageous may be prioritized to be processed on the GPU, for example. In a portable electrical measurement instrument powered by a battery, it may be desirable to balance processing speed with power consumption, managing the data to achieve a maximum level of performance while minifying power consumption to as low as possible. Embodiments of electrical measurement instruments in accordance with the present invention can benefit in unconsidered ways by incorporating a GPU accessible to a CPU. Such embodiments can improve performance of plug-in electrical measurement instruments, and/or reduce power consumption for portable, battery powered electrical measurement instruments.
The foregoing description of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to practitioners skilled in this art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.
