Military and aerospace designs have long relied on VME, and (more recently) its successor VPX. But developers now have the option to use AdvancedTCA* (ATCA) and MicroTCA (uTCA) in their rugged designs. Which choice is better? This blog will look at the pros and cons of VME/VPX and ATCA/uTCA. It will explore the best uses for each standard and highlight example products for each.
Let’s start by reviewing the current state of affairs in commercial off-the-shelf (COTS) mil/aero markets. Figure 1 illustrates the market size of various COTS technologies. Note that VME & VPX remain by far the largest markets, but the ATCA and uTCA markets are growing at significantly faster rates.
COTS Computing Solution
VME & VPX (VITA 46)
Compact PCI (cPCI)
PCI with passive backplane
Figure 1. Mil/aero market sizes for COTS computing technologies in millions of USD. (Source: VDC Research Group via Radisys)
Much of the growth of the ATCA and uTCA markets can be attributed to emerging requirements for high-performance equipment. Figure 2 shows how various COTS standards map to key mil/aero market segments. As shown in this figure, ATCA and uTCA are well suited to high-performance applications such as image processing and command center applications.
Figure 2. Mil/aero market segments served by COTS suppliers. (Source: Radisys)
At the same time, VME and VPX are not going away any time soon, and these established technologies can address many of the same markets as ATCA and uTCA. Deciding which technology to use requires a careful analysis of the strengths and weaknesses of each. In this blog we can only scratch the surface of this question. To dive deeper, I recommend the Radisys white paper When High Performance Really Matters in Military/Aerospace.
For our brief overview, let’s start by reviewing the genesis of the competing standards. The development of VME and VPX has been driven primarily by the needs of mil/aero markets. As a result, these standards offer many mil/aero-friendly features that are not found in ATCA systems. For example, VPX systems are available with liquid cooling, a feature that is rare (although not unheard of) in ATCA and uTCA systems. For that matter, the entire VPX ecosystem—which includes not only hardware but also supporting software, services, and so on—is heavily focused on the needs of mil/aero applications. This focus can make a big difference in reducing time to market and in meeting tough certification requirements.
In contrast, ATCA and uTCA are driven primarily by the needs of telecom markets. In the past this would have been a handicap for ATCA, but as the battlefield becomes increasingly wired, the needs of mil/aero markets are converging with the needs of telecom applications. Thus, ATCA and uTCA are well suited to the needs of communications-centric mil/aero applications. On the other hand, the specialization of VPX makes it a better choice for many traditional mil/aero markets.
Another factor to consider is interoperability. ATCA was created specifically to ensure interoperability between different manufacturers’ hardware. In contrast, interoperability has been a sticking point for VPX. The OpenVPX (VITA 65) interoperability framework ratified earlier this year should help matters considerably.
From a technical perspective, there are a number of important differences between the standards. As shown in Figure 3, many of these differences relate to the size of the systems: ATCA boards are larger and (generally) have greater power budgets than VPX boards. Keep in mind that ATCA and VPX systems have multiple blades, so a simple blade-to-blade comparison does not tell the whole story.
6U: 233 x 160 mm
Area: 373 cm²
8U: 355.6 cm x 280 cm
Area: 996 cm²
Board Power Consumption (max)
115 watts at 5 V (12 V and 48 V options also available)
1 Gbps, moving to 10 Gbps
1 and 10 Gbps, moving to 40 Gbps
Adoption of Standard
Figure 3. Technology comparison. (Source: Radisys)
To illustrate the advantages of each approach, let’s consider two example systems. On the ATCA side we have the new C2 Server developed jointly by Radisys, LCR Electronics, and Astute Networks. This 6U server is said to be the first pre–integrated, portable ATCA platform for rugged, ground mobile mil/aero applications. The C2 Server supports up to eight Intel® Xeon® processor 5600 series server-class processors. Virtualization through VMWare ESXi allows the server to use multiple operating systems for application consolidation, while VSphere 4.0 support enables fault tolerant configuration of the various operating systems. Other key features include:
- 6-slot 6U AC chassis ruggedized to meet the MIL–STD–810 specification
- Two 10G switches, each supporting 5x10GbE uplinks and wire speed L2/L3 switching
- Dual- and single-socket processor boards
- iSCSI storage blade with capacities of up to 3TB per slot and support for Solid State Disk (SSD), Serial Attached SCSI (SAS) and Serial ATA (SATA) hard disk technologies
Representing VPX we have the SVME/DMV-1905 from Curtiss-Wright Controls. This 6U board targets demanding storage, data logging and sensor processing applications. It features:
- A 2.53GHz Intel® Core™ i7 processor with Intel® SSE 4.2 support for excellent floating point performance
- Up to 8GB of DDR3 connected directly to the processor for a peak throughput of 17 GB/s
- Up to 8GB of Flash
- Ruggedization according to AC 0, 100, CC 100, 200
Whichever technology you chose, it is clear that COTS technologies are here to stay. I am confident that both VPX and ATCA will continue evolving to meet the needs of mil/aero markets.
Radisys is a Premier member of the Intel® Embedded Alliance. Curtiss Wright Controls Embedded Computing is an Affiliate member of the Alliance. Astute Networks is a General member of the Alliance.
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