MicroTCA tabbed for next-gen test

4MicroTCA (mTCA) technology was the highlight of the 25th PICMG Interoperability Workshop (IW) held at DESY in Hamburg, Germany earlier this year, as pilot users from the scientific community collaborated with hardware vendors to test the latest equipment and resolve any compatibility issues. While the first mTCA data acquisition (DAQ) systems are currently being installed at locations such as CERN during the facility's "long shutdown," ongoing advances in the mTCA specification could have implications for larger system upgrades scheduled at the research laboratory for 2018 and 2022-2023, as well as other emerging test and measurement markets.

From VME to CompactPCI (cPCI) to AdvancedTCA (ATCA), it seems that every standardized platform is eventually recruited for instrumentation and test applications. Low cost and long lifecycles have kept test and measurement architectures such as VXI and PXI in service for decades and deployed in applications from mobile/communications testing to industrial automation to high-energy physics (HEP). However, as next generation systems capable of higher performance begin to demand more from their test system counterparts in terms of timing accuracy, transfer speeds, and frequency range, these incumbent architectures have begun to give way to newer MicroTCA (mTCA) systems thanks to improvements in flexibility, compatibility, and dynamic range.

“Many VME and cPCI systems were targeting test and measurement systems for mobile networks and associated (media) gateways,” says Heiko Körte, Director of Sales & Marketing at N.A.T. (www.nateurope.com). “MicroTCA was a natural transition for our customers when moving on to the next generation of technology, providing higher bandwidths with shortened latencies, and at the same time a full feature set including redundancy, remote management, and so on.

“We expect many VME and cPCI customers to migrate to mTCA, especially because of its safe future perspective and roadmap,” Körte continues. “We even see AdvancedTCA customers investing into MicroTCA because of the higher degrees in flexibility and scalability. MicroTCA will definitely continue to pave its way into the test and measurement market, not only in comms and mil/aerospace and telemetry where it is already deployed today, but also in the medical arena in test systems for high-performance parts in radiation and nuclear meds, such as detectors and related data acquisition (DAQ) systems.

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Sidebar 1: AdvancedTCA interposers ease protocol analysis in MicroTCA

“The MicroTCA set of specifications, especially .0 and .4, define all features such as remote management, hot swap, and rear I/O as mandatory, which are required to build data acquisition (DAQ) systems for test and measurement, including footprints from 1U to 9U,” Körte says (Figure 1). “Due to the switched communication and the passive backplane, a MicroTCA system easily adapts to the required bandwidth and architecture, such as PCI Express, Serial RapidIO (SRIO), or XAUI. This makes the same system architecture usable in different environments.”

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Figure 1: The NAT-MCH-PHYS80 addresses high-bandwidth requirements for both Advanced Mezzanine Cards (AMCs) and the rear transition module (RTM) slots of the MicroTCA Carrier Hub (MCH) in MicroTCA.4 (mTCA.4) systems, as well as the optical and copper uplinks in PCI Express-based (PCIe-based mTCA.4 platforms.

High-performance test for HEP

MicroTCA technology is seeing adoption in an array of bleeding-edge DAQ applications, from quality of service (QoS) analyzers to load generators for mobile user simulation to traffic inspection that typically demand 12- to 14-bit platforms operating between 1 – 3.6 Giga Samples per second (GSps) over the 10 MHz to 4 GHz range. However, an environment of particular interest to the mTCA ecosystem is the HEP community, where the architecture has begun to take hold at research institutes such as DESY, SLAC, and CERN. In these DAQ scenarios high-speed performance and data bandwidth are mission critical, prompting scientists to select the MicroTCA.4 specification, says Aksel Saltuklar, Engineering Director at Elma Electronic, Inc. (www.elma.com).

“MicroTCA for Physics (mTCA.4) is proving to offer some of the high-performance features customers seek in test equipment as well,” Saltuklar says (Figure 2). “Applications found in high-energy physics (HEP) for example, require raw data readouts or some equivalent in data bandwidth. This can be challenging due to limited on-board memory, speed, and the bandwidth of communication links. An example is a 16-bit, 10-channel digitizer with a sampling rate of 125 MHz that uses the whole bandwidth of 64-bit DDR3 memory – when using PCI Express Gen1 x4, you can only stream 3 such channels. In such cases, restrictions are placed on the sampling frequency or acquisition period. For example at DESY, the raw data is acquired only for 2 ms.

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Figure 2: Elma’s MicroTCA.4 (mTCA.4) platforms are well-equipped for demanding test and measurement applications.

“Our customers always want to have fast analog to digital converter (ADC) performance in the range of GHz, and preferably 16-bit resolution with a maximum dynamic range, without switching analog stages,” he adds. “Specific application requirements must be taken into account when you get such descriptions. It seems that for low-level radio frequency (LLRF) systems, 16-bit is typical and not too much dynamic range is needed. For delay line applications, which we recently dealt with, resolution could be more relaxed, yet 5 GHz sampling was required with high dynamic range.

“40 Gigabit Ethernet (GbE) mTCA will enable data rates high enough to gather more critical data in a system,” Saltuklar continues. “Projects done in cooperation with DESY, as well as ESS, SLAC, and others based on superconducting technology, are using mTCA.4 because they can utilize existing experience and products. Other institutes are evaluating different possibilities, for example ITER, which is trying to run the same apps on PXIe, ATCA, and mTCA before selecting the best system.”

40G looking forward

40 GbE may seem overkill at present, as many applications are just now beginning to migrate to 10 Gigabit backplane speeds. But with the growing appetite of today’s high-performance embedded computing (HPEC) platforms, the 40G innovation will not only meet the requirements of today’s most sophisticated designs, but provide a future-proof feature set for the test and measurement community on the whole.

“40G will close the final gap between MicroTCA and ATCA, however, it will first be only the high-end systems that benefit from this bandwidth,” Körte explains. “At the moment many customers get along with multiple 1 GbE connections or single 10 GbE. However, again, for these customers having a perspective and a clear migration path is very important as it means that they can stay with mTCA for the next 10-15 years.”

The 3rd MicroTCA Workshop for Industry and Research will be held at the DESY facility in Hamburg, Germany from December 8-11. Interested parties can find out more at mtcaws.desy.de.