Currently digitizers have a bottleneck caused by having to use either the host PC's central processor with 8 or 16 cores or a FPGA that is complex to program. Spectrum Instrumentation claims to solve this problem with its new Spectrum CUDA Access for Parallel Processing (SCAPP) software option that provides an easy-to-use yet extremely powerful way to digitize, process and analyze electronic signals.

SCAPP allows a CUDA-based Graphical Processing Unit (GPU) to be used directly between any Spectrum digitizer and the PC. The big advantage is that data is passed directly from the digitizer to the GPU where high-speed parallel processing is possible using the GPU board's multiple (up to 5000) processing cores. That provides a significant performance enhancement when compared to sending data directly to a PC that may have only 8 or 16 cores. It becomes even more important when signals are being digitized at high-speeds such as 50 MS/s, 500 MS/s or even 5 GS/s.

The Spectrum approach uses a standard off-the-shelf GPU, based on Nvidia's CUDA Standard. The GPU connects directly with the Spectrum digitizer card, with no more CPU interaction, opening the huge parallel core architecture of the CUDA card for signal processing. The structure of a CUDA graphics card fits very well as it is designed for parallel data processing, which is exactly the same as most signal processing jobs. For example, the processing tasks of data conversion, filtering, averaging, baseline suppression, FFT window functions or even FFTs themselves can all be easily parallelized.

The SCAPP driver package consists of the driver extension for Remote Direct Memory Access (RDMA) that allows the direct data transfer from Digitizer to GPU. It includes a set of examples for interaction with the digitizer and the CUDA-card and another set of CUDA parallel processing examples with easy building blocks for basic functions like filtering, averaging, data de-multiplexing, data conversion or FFT. All the software is based on C/C++ and can easily be implemented and improved with normal programming skills. Starting with tested and optimized parallel processing examples gives first results within minutes.

 

The interconnection between digitizer and GPU is based on PCI Express. Depending on the selected Spectrum digitizer card, a continuous throughput of more than 3.0 GByte/s between the digitizer and GPU can be achieved. That is enough to support continuous acquisition from a one channel 8-bit digitizer sampling at 2.5 GS/s or a two channel 14-bit unit running at 500 MS/s. By using one of Spectrum's transfer-bandwidth saving data acquisition modes, like Multiple Recording, the sampling speeds can be even much higher.

 

CUDA cards are scalable with processing cores between 256 and 5000, with memory of several GBytes and up to 12.0 Trillion Floating Point Operations (TFLOP) per second. A small sized card with 1k cores and 3.0 TFLOP is already capable of doing continuous data conversion, multiplexing, windowing, FFT and averaging at two channels 500 MS/s with a FFT block size of 512k – and that can run for hours.

The SCAPP package is a driver extension for all Spectrum cards. It can be used with the ultra-fast digitizers of the M4i platform (250 MS/s 16 bit, 500 MS/s 14 bit or 5 GS/s 8 bit) as well as the latest medium performance M2p platform (20 to 80 MS/s multi-channel 16 bit). The basic RDMA functionality is available under a Linux operating system.