Maintaining one’s competitive edge in this economic downturn often comes down to the tools used to get the job done. In terms of test instruments, this is especially true.
Without oscilloscopes, spectrum analyzers, and other instruments with the speed and bandwidth to capture today’s high-speed serial bus traffic, it’s virtually impossible to verify the performance of many systems. On top of that, the same instruments are essential to ensure that these systems comply with protocol standards for those serial buses.
So here’s a look at some of today’s latest, and highest-performing, laboratory-grade test instruments. Some of these machines are pricey indeed, but their prices pale in comparison to the cost of missing a market window or being denied standards certifications.
SCOPES GO BROAD AND BIG
These days, test instruments often are called upon for more than one task. Thus, instrument makers are routinely expected to package the capabilities of more than one instrument in a single box. Not only that, but each blade of that Swiss-army-knife instrument has to be at least as sharp as it would be in a high-end standalone version.
Agilent’s latest additions to the upper reaches of its scope lineup achieve this trick handily. The six models that comprise the Infiniium 9000 series sport true analog bandwidths up to 4 GHz. Not only that, the scopes also are fitted with the industry’s largest screens: a 15-in. XGA LCD (Fig. 1).
Designers of high-end embedded systems typically need scopes with bandwidths of at least 1 GHz these days. Users have a range of requirements with respect to oscilloscopes, not necessarily knowing what kinds of measurement tasks they may have from day to day. “Protocol issues, debug challenges, and questions of compliance are common to many designs,” says Richard Markley, Infiniium sales manager at Agilent. Further, engineers often find themselves with limited bench space and shared oscilloscopes.
To address that need for a multifaceted instrument, the Infiniium 9000 series instruments are essentially three instruments in one: an oscilloscope, a logic analyzer, and a protocol analyzer. As an oscilloscope, the Infiniium 9000 series enables users to quickly visualize signals, providing fast autoscaling and drag-and-drop measurement capabilities. It delivers precision and parametric detail, with standard sample rates of up to 20 Gsamples/s. At the same time, it enables captures of long signal traces—10 Mpoints worth of memory is standard, and up to 1 Gpoint worth is optional.
In addition to their analog specifications, the units offer 16 integrated digital channels running at 2 Gsamples/s. These mixed-signal oscilloscope (MSO) channels function as a logic analyzer, allowing users to view or trigger on data buses or control signals to observe and analyze digital timing relationships. These capabilities permit quick debugging of systems with FPGAs or embedded microprocessors/ microcontrollers.
Because almost all designs integrate serial communications protocols and/or high-speed serial channels such as PCI Express, Agilent endowed the Infiniium 9000 series with a set of protocol analysis capabilities. “Not only can you see the physical layer, but you can go up into the protocol stack and see the packets being passed around,” says Markley. “This can help you tell if problems are related to the protocol itself or something else.”
With in-scope protocol viewers for USB and PCI Express, engineers can extend their debug and testing reach without the need to hook up additional instruments. Users can see serial packet contents, trigger at the protocol level, and non-intrusively debug these serial buses. Packets are viewable down to bit level to isolate faults to analog or logic sources.
With the scopes comes a broad range of debug and compliance software that optionally supports up to 25 different applications. These give designers meaningful insights into common serial buses, FPGAs, and RF measurements, allowing for quick compliance testing. debug applications include protocol triggering and viewing for PCI Express and USB; serial decode and triggering for i2c, SPI, CAN, and RS-232 buses; and core-assisted debug of designs with Altera or Xilinx FPGAs.
SWEEPING THE SPECTRUM
The prevalence of digital RF technology in many systems has created some interesting test challenges. digital RF is an environment combining gigahertz signals with mixed-signal complexities, in addition to digital baseband having to translate over into the RF domain. Typically, multiple radios come within a single platform. signal bursting and hopping combine with transients to make verification and troubleshooting a difficult task.
That’s roughly where Tektronix’s enhancements for its RSA6000 series of spectrum analyzers enters the picture. in 2006, the company added its DPX spectrum processing technology to these instruments, enabling users to observe and analyze these kinds of phenomena.
Tektronix recently upgraded the scopes again, adding swept spectrum analysis to the DPX transform engine. The resulting transformational swept DPX capability provides wideband signal search with the highest probability of detection available.
The DPX engine collects hundreds of thousands of spectrum sweeps per second over a bandwidth slice of 110 MHz. As a result, the engine can be swept across the full input range of the RSA6000 series (up to 14 GHz). Further, a user-defined dwell-time setting allows designers to “stare” at bands of interest to capture transients at each point in the sweep.
For example, in analyzing a 10-ns impulse signal, the RSA6000 instruments can zero in on internal interference within the pulse generator (Fig. 2). This example shows a bandwidth of 1 GHz, demonstrating their ability to take DPX triggering to a wideband stage.
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