INDUSTRY FOCUS MILITARY, AEROSPACE & DEFENCE


PRECISION TIMING: AT THE HEART OF DEFENCE OPEN ARCHITECTURE SYSTEMS


Tyler Hohman, director of business development, Aerospace & Defence, SiTime, discusses how precision timing helps ensure interoperability with precisely synchronised data transmission


T


iming plays a central role in ensuring that electronic systems operate reliably and harmoniously – and this is never more


critical than in the battlefield. Here, electronic systems such as unmanned vehicles, ground sensors, command centres and tactical communications must work in coordination. When multiple platforms are deployed in joint


operations – for functions such as real-time drone video, jamming enemy signals or data communication – they must be synchronised to ensure data transmission is cohesive for reliable and timely decision making and action. If various subsystems, provided by different


manufacturers and introduced at different times, are not synchronised, it complicates defence operations. As the industry moves toward open architecture implementations, timing misalignments can lead to latency issues, degraded performance or, in the worst cases, system failure.


THE OPEN-SYSTEM FUTURE OF DEFENCE Open architectures, such as those outlined in Modular Open Systems Approach (MOSA), Sensor Open Systems Architecture (SOSA), C4ISR/EW Modular Open Suite of Standards (CMOSS) and OpenVPX, are revolutionising the design, integration and


50 DESIGN SOLUTIONS FEBRUARY 2025


maintenance of defence systems. These standards emphasise modularity, flexibility and scalability, allowing military platforms to quickly integrate new technologies and achieve cost-effective updates. For systems built on modular open


standards, the system requirements for communications, command and control, electronic warfare, intelligence gathering and others, dictate the timing device requirements. Key considerations include: • Size, weight, power and cost (SWaP-C) reduction: Military platforms, particularly mobile and airborne systems, require compact, lightweight and energy-efficient components. Design engineers also prefer readily available, off-the-shelf components with reasonable lead time and continuity of supply.


• Shock, vibration and temperature resilience: Reliable and stable frequency is essential to maintain optimal performance. Even minor variations can severely degrade system accuracy and functionality. Military systems must withstand harsh environments. These include changing and extreme temperatures, high vibration levels and severe shock conditions. Timing components must be robust and reliable.


• Holdover performance: GPS is the source of reference timing in over 700 DoD weapon


systems. Unfortunately, GPS is vulnerable to attacks. Maintaining accurate timing even when a GPS signal is unavailable or untrustworthy is critical for successful military operations. Precision timing devices are distributed


throughout electronic systems and must perform in a wide variety of contexts to ensure that all subsystems remain synchronised. The ability to maintain functional and accurate time in complex and high-stakes defence environments can make the difference between mission success and failure.


WHY MEMS TIMING IS THE RIGHT CHOICE FOR DEFENCE Micro-electro-mechanical systems (MEMS) silicon timing technology is a means for solving some critical defence challenges. Ruggedised precision MEMS-base oscillators such as temperature-compensated oscillators (TCXOs) and oven-controlled oscillators (OCXOs) provide significant advantages over quartz-based products. These improvements include: • SWaP reduction: COTS Ruggedised MEMS oscillators are proven low SWaP solutions. For instance, the SiT5543 in a 7mm x 5mm package consumes only 135mW, making it an ideal choice for platforms where SWaP constraints are a significant concern. This device can replace a quartz OCXO that would consume almost 4X the energy at 500 mW in a footprint 10X to 20X larger.


• Frequency stability over temperature: MEMS timing technology is advancing, continuing to provide a range of options to replace quartz TCXOs and OCXOs. SiT5348 MEMS Super-TCXO is rated at +50 ppb over a wider temperature range of up to -40 to 105˚C with repeatable and predictable frequency with no frequency dip or activity jump. The new SiT5543 TCXO rated at +5 ppb over -40 to 95˚C is the only TCXO that achieves this temperature stability with lower power, smaller size and higher reliability than a quartz OCXO. The new SiT7111 oven-controlled MEMS oscillator delivers + 1 ppb over -40 to 95°C, a wider temperature range than most quartz OCXOs.


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