In an era where precision and reliability are paramount in satellite communications, even minor sources of interference can have significant consequences. One often overlooked yet critical issue is the impact of high-speed data ports—such as USB 3.0—on satellite line-of-sight (LOS) signals. While USB 3.0 is essential for modern connectivity, its unintended electromagnetic interference (EMI) can disrupt any number of satellite communications, leading to degraded performance or signal loss. This white paper explores the mechanisms behind this interference, its implications for satellite-based applications, and potential mitigation strategies to ensure seamless connectivity in critical operations.
High-frequency devices, like high-speed processors or high-speed communication buses (say, USB3 or PCIExpress) are known to produce electromagnetic interference (EMI) in the 1.2 – 1.5 GHz range, where all GNSS signals reside.
GNSS signals are emitted from satellites 20,000 km away, so they are weak (like -130dB). Any interference in that band will outpower those signals, and the receiver will not see the satellites.
The only solution is:
- To keep the GNSS antenna away from those sources of interference, AND shield those devices and their communication cables.
Note: Away generally means as far as practically possible in the application.
Note: Shielding means entirely confining those high-frequency devices in Faraday cages made of conductive materials (see https://en.wikipedia.org/wiki/Faraday_cage for the idea), preferably grounded.
The cage should also be connected to shield cables coming out of those devices; otherwise, the wires will emit antennae for high-frequency interference and drastically reduce the effectiveness of the cage.
The thickness of the conductive shield can be minimal, as we are talking about GHz band – see the linear log-log slope on the Wikipedia page. I would say that even 0.005 mm aluminum film will shield 1GHz waves, so it does not add much weight.
That means, even conductive metallic paint on the internal surface of the high-frequency device housing should be enough.
Grounding the shield means connecting it to an object of high capacitance, like the vehicle body or the return power rail.
As reliance on satellite communications continues to grow across industries—from aerospace to navigation—understanding and addressing potential sources of interference is crucial. High-speed data interfaces like USB 3.0 introduce EMI that can compromise satellite LOS, impacting performance in ways that may not be immediately obvious. By recognizing these challenges and implementing effective shielding, filtering, and layout considerations, engineers and system designers can minimize disruption and maintain the integrity of satellite communications. Proactive solutions today will ensure the resilience of tomorrow’s satellite-dependent technologies.