MOSA provides cost savings, performance, flexibility for EW digital receivers

3The use of a Modular Open System Architecture (MOSA) can provide cost savings, and performance and upgrade flexibility gains, in digital receiver designs for use in Electronic Warfare (EW). Some approaches to employing MOSA in digital receivers are illustrated, as well as the benefits achieved.

The current environment for Electronic Warfare (EW) programs is a challenging one, with new and emerging threats, asymmetrical problem sets, and a rapidly evolving opponent that makes great use of off-the-shelf hardware to rapidly deploy capabilities (for example, garage door openers as IED triggers), to name just a few issues. Traditional EW solutions targeted radar systems and conventional communications networks. They were not designed to counter the unconventional use of modern convenience appliances, nor were they designed to support incorporating the degree of rapid innovation and threat adaptation demonstrated by adversaries. Not only that, historically, digital receiver implementations – including Digital RF Memories (DRFMs) – have been application specific to support very specific limitations or constraints in the upgrade to fielded systems.

Thus, the challenge is integrating the benefits of an application-specific digital receiver with upgrade flexibility and cost savings – while still achieving performance objectives. One approach to reduce EW and signal processing life-cycle costs while shortening the time to deliver solutions to the warfighter has been the adaptation of a Modular Open System Architecture (MOSA) to permit easier technology refresh implementation paths and use of nonproprietary hardware and software solutions (see Sidebar 1). And a MOSA-based digital receiver that relies on open standards can still achieve performance objectives, as illustrated in the following discussion.

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Sidebar 1: A closer look at the Modular Open System Architecture (MOSA) standard
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Open digital receiver challenge examples

As mentioned, digital receivers and DRFMs have typically been application specific; thus, the challenge in implementing a digital receiver into an EW system or application lies in achieving application-specific performance levels while utilizing a cost-efficient, flexible, open standards-based device. For operational effectiveness, a digital receiver needs to have very high spurious performance, high selectivity, and wide dynamic range performance, all of which can be challenging to achieve while fully supporting an open standard interface. A flexible but generally high sample rate and wide instantaneous bandwidth are also required key performance parameters if a digital downconversion is to be employed.

In the examples presented here, two sets of custom, application-specific hardware are replaced with a MOSA solution set with a high degree of commonality between two similar but unique functions. A varying channel count and varying sample rate and resolution on the Analog-to-Digital Converters (ADCs) are what differentiate the receivers.

SIGINT/ELINT digital receiver example

The first MOSA implementation example comprises two digital receivers: a Signals Intelligence (SIGINT) direction finding receiver and an Electronic Intelligence (ELINT) wideband detection receiver. In each case, the digital receiver base card is identical between the two implementations, with the FMC mezzanines acting as “personality modules” to define the functionality of the open-based architecture (see Table 1 and Figure 1). A common FPGA interface to the FMC mezzanine is easily adaptable for each. This provides the advantage of the FPGA data plane (data movement) infrastructure being common between different applications. Moreover, the control software interface is reusable for both applications, thus permitting the end user to focus on algorithmic development and employ existing data and control plane functions.

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Table 1: Comparison of two MOSA-based receivers: a SIGINT direction finding receiver and an ELINT wideband detection receiver
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Figure 1: MOSA SIGINT/ELINT digital receiver
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A DRFM/digital receiver example

This example of a MOSA implementation is representative of an application-specific design for an airborne pod/UAV installation. In this system, a digital receiver is to provide signal environment situational awareness when coupled with a DRFM. As a cost-reduction effort over the fully custom configuration, the system is partitioned into: 1) The wideband situational awareness OpenVPX receiver; 2) the OpenVPX DRFM; and 3) the fast tuning RF OpenVPX Down/Upconverter RF control. For this implementation, the digital receiver and DRFM base cards are identical, while the FMC mezzanines are reprogrammed to define the functionality of the open-based architecture for each function. The FPGA interface to the mezzanine is readily adaptable for each FMC.

The open DRFM function needs to have a low latency/insertion delay, while fully supporting an open standard interface. A flexible, but high sample rate and wide instantaneous bandwidth are required, while incorporating a very fine delay resolution, high spectral purity/low spurious content, and wide instantaneous dynamic range.

The digital receiver needs to have very high spurious performance, high selectivity, and wide dynamic range performance, while fully supporting an open standard interface. A flexible, but generally high sample rate and wide instantaneous bandwidth are also required key performance parameters if a digital downconversion is to be employed. In this example, we see a single base card for both the wideband digital receiver and the DRFM. The base card uses a common FMC card for each with unique IP within the FPGA to achieve the performance standards needed.

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Table 2: Open DRFM function and ELINT wideband detection system can both utilize MOSA
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Figure 2: MOSA 3U VPX digital receiver and DRFM
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Future savings with MOSA

The examples provided show that the using a Modular Open System Architecture can provide cost savings in digital receiver designs for use in electronic warfare through: shortening the time to deliver solutions; providing greater flexibility for incorporating feature growth as the systems mature; and serving as nonproprietary hardware and software solutions that provide performance comparable with or exceeding that of application-specific EW digital receivers.

Chris Lewis is Chief Technical Officer at Mercury Defense Systems. He helped cofound Mercury Defense Systems (formerly KOR Electronic) in 1986. His background in the design of high-speed multi-bit A/D and D/A modules contributed to improved performance of flight-qualified DRFM-based EA/EP equipment and radar environment simulator systems. He has prior electronic warfare experience at Design Engineering Laboratories, Hughes Aircraft Company, and Boeing Aerospace Company. He can be contacted at CLewis@Defense.MRCY.com.

Alton Graves is Technical Director for Microwave and Digital Systems at Mercury Systems and serves as the Lead Hardware Architect for IF & Digital products within Mercury Systems’ Microwave and Digital Solutions Group. Alton was a key contributor in the architecture for Mercury’s (VME and Critical Systems magazine Editor’s Choice) award-winning SCFE product. He has 15 years of experience designing mixed-signal circuitry and FPGAs. Before joining Mercury in 2003, he was a senior engineer for a major networking company. Prior to that, he served as both a Xilinx and Altera field applications engineer. He can be contacted at AGraves@MRCY.com.

Mercury Defense Systems is an operating subsidiary of Mercury Systems, Inc. www.mrcy.com