VIAVI Solutions just rolled out their game-changing, patent-pending ePRTC360+ holdover solution, a cesium-free alternative that shields critical power grids, transportation, aviation, public safety, 5G networks, and AI data centers from GNSS disruptions. It’s the first non-cesium option to nail the ITU-T G.8272.1 standard.
That standard demands tight holdover performance
Under 30 ns short-term drift right after GNSS loss, and less than 100 ns over 14 days all traceable to UTC. Cesium atomic clocks were the only ones pulling this off before; now VIAVI’s ePRTC360+ joins the club.
They’ve battle-tested it in real-world jamming and spoofing scenarios, both defense and commercial, and folded it into their SecurePNT 6200 series.
It holds 100 ns accuracy indefinitely during GNSS blackouts via the resilient altGNSS GEO-L service.
Pair it with VIAVI’s beefed-up SecureTime GEO anti-jam antenna and enhanced anti-spoofing setup, which taps eGNSS GEO signals plus GPS/GNSS-NMA authentication to spot and block spoofing.
What sets it apart
While standard GNSS signals get swamped by cheap jammers, VIAVI’s GEO-L service uses encrypted, laser-focused L-band beams from geostationary satellites independent of GNSS.
Teamed with that SecureTime GEO antenna, it gives rock-solid anti-jam protection, keeps the internal rubidium oscillator on track, and lets the system seamlessly switch sources, even under heavy jamming, spoofing, or sneaky meaconing.
Cheaper than cesium clocks, the ePRTC360+ lets operators scatter them network-wide, not just at the core. They pair nicely with core cesium setups too, creating meshed PTP backups for extra resilience against local or widespread threats.
Cesium clocks bring challenges
shock-prone, days-long startups, export headaches (ECCN 3A001.i), 40-day GNSS lock-in periods, finicky shipping rules, seven-year tube replacements, and hazardous disposal.
The ePRTC360+ skips all that hurdles, slots easily into any grandmaster clock, cuts ownership costs, and meets ePRTC specs without the fuss.
Leadership Comments
“The Cesium-less ePRTC360+ exceeds leading-edge Cesium-level holdover performance and does this for significantly lower price. This enables deployment across the sync network, particularly at edge sites which were previously cost-prohibitive with Cesium holdover clocks,” said Doug Russell, Senior Vice President and General Manager, Aerospace and Defense, VIAVI.
Catch it live at VIAVI’s Stand 5B18 at Mobile World Congress Barcelona 2026 (March 2-5).
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