PXI Newsletter

Newsletter: Phase-Comparison Direction Finding			1/27/2010
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From the Co-Chair of PXISA Marketing, Walter Strickler:

PXI System Alliance Links

Welcome to the January 2010 edition of the PXI Newsletter. Our intent is to educate and inform you about how the PXI standard is being used in modular test systems for a wide variety of industries.

mkt research1 As we usher in a new decade for PXI, we should pause a moment to reflect on how the market has evolved in the last decade. At the mid-way point, Frost & Sullivan estimated the market at $215M with an expected compound annual growth rate of nearly 25%. While figures may vary for the market size in 2010, there is no debate that the PXI market has experienced phenomenal growth.

Over the decade, we have also seen an evolution and expansion of the standard. Just a couples months ago, we saw the release of a new PXI MultiComputing™ specification that enables multi-controller systems with high performance communication.

Even in a struggling economy where many companies have elected to curb their participation in industry consortia, the PXISA has continued to see growth in membership. Today we are 60 companies strong.

We have high expectations for PXI over the next ten years and we will continue to do our part to help us all succeed through our charter to:

Promote the PXI Standard
Ensure interoperability
Maintain the PXI Specification

In this issue, we talk about using PXI instrumentation for phase-comparison direction finding in our main article and the basics of PXI Express in our standards article. We wish you much success in the coming year and new decade.

To join our mailing list, go to http://www.pxisa.org/signup.html

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Main Article

Phase-Comparison Direction Finding

Remember jumping on a trampoline as a child and “stealing the bounce” of a friend? A perfectly timed jump would create the destructive interference necessary to bring the unfortunate jumper to their knees. Sometimes, you would try “giving a bounce,” using constructive interference to send your friend much higher than they could have made it on their own.

This behavior was observed in waves long before your experiments on the modern trampoline and has found its way into many applications. In 1905, Karl Ferdinand Braun showed this property could actually be used to enhance a radio transmission in a given direction by using two or more antennas. Since then, applications such as beamforming; multiple input, multiple output (MIMO) communications; and direction finding (DF) have all benefited from this effect.

Figure 1 illustrates two transmitters and two possible scenarios of a signal source creating constructive and destructive interference

Thanks to all our readers.
Bob Helsel, Editor
www.pxisa.org

Standards Article

The Basics of PXI Express

PXI Express integrates PCI Express into the PXI backplane. We will first go over the advantages of PCI Express over PCI.

PCI Express was introduced to improve upon the PCI bus platform. The most notable PCI Express advancement over PCI is its point-to-point bus topology. The shared bus used for PCI is replaced with a shared switch, which provides each device its own direct access to the bus. Unlike PCI, which divides bandwidth between all devices on the bus, PCI Express provides each device with its own dedicated data pipeline. Data is sent serially in packets through pairs of transmit and receive signals called lanes, which enable 250 MBytes/s bandwidth per direction, per lane. Multiple lanes can be grouped together into x1 (“by-one”), x2, x4, x8, x12, x16, and x32 lane widths to increase bandwidth to the slot. PCI Express dramatically improves data bandwidth