The focus of the SIWG has been primarily on the SI concepts as applied to RF stimulus and measurement systems. Data
intensive applications, like RF testing, require a high-bandwidth, low-latency bus to connect the IF digitizers to the
processor (see Figure 5).
Figure 5. Synthetic Instrument RF Block Diagram
For example, to digitize a 50 MHz wide RF signal requires 100 Mbytes/s of bandwidth (at 2 bytes of resolution per
sample). For an input and output channel, this grows to 200 MB/s. And for increasingly common multi-channel, or
MIMO (Multi Input, Multi Output) applications, the bandwidth required can quickly scale to multiply gigabytes per
second. PCI Express, and cabled PCI Express in particular, is a leading contender for this high speed link because of its
excellent technical capabilities, wide commercial adoption, and low-cost infrastructure.
Cabled PCI Express is based on PCI Express and so provides a scalable, high-bandwidth, low-latency bus for
chip-to-chip, board-to-board, and box-to-box applications. In the past some data intensive applications couldn’t transfer
the data fast enough to the host PC and so the data was processed in the box instrument using vendor-defined software
and hardware. Cabled PCI Express opens up a new larger and faster pipe to the host PC so more applications can take
advantage of user-defined software and hardware for measurement processing and analysis. Today NI uses cabled PCI
Express to connect host PCs to PXI chassis with MXI Express. It currently sustains transfer rates of 110 MB/s for a x1
link and 798 MB/s for a x4 link. In the future, cabled PCI Express may offer a compelling bus solution for synthetic
instrumentation.
Relevant NI Products and Whitepapers
National Instruments, a leader in automated test, is committed to providing the hardware and software products
engineers need to create these next generation test systems.
Software:
•
NI TestStand Test Management Framework
•
LabVIEW Graphical Programming Environment
•
Signal Express Interactive Measurement Software
Hardware:
•
Modular Instruments (Oscilloscopes, Multimeters, RF, Switching, and more)
•
Multi-function Data Acquisition
•
PXI System Components (Chassis and Controllers)
•
Instrument Control (GPIB, USB, and LAN)
Cabled PCI Express as a Standard
Interface for Virtual and Synthetic
Instruments
Document Version 1
© 2006 National Instruments Corporation. All rights reserved.
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