Jeffgeerling iconJeffgeerlingSep 4, 2026 ~1 min source read

Rebuilding a 1995 GPS Time Server so I don't get Telstra'd

In June I purchased this TrueTime XL-AK time server, so I could learn more of the history of GPS-based time. I received it on June 22, and just 16 days later a similar GPS time server took down Australia's cell service for 12 hours!

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In June I purchased this TrueTime XL-AK time server, so I could learn more of the history of GPS-based time.

I received it on June 22, and just 16 days later a similar GPS time server took down Australia's cell service for 12 hours!

Over the past couple weeks, I've 'restomodded' this device with a Raspberry Pi, to build a stratum 1 NTP Time server, which I'd like to eventually add to the NTP Pool.

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The useful part

In June I purchased this TrueTime XL-AK time server, so I could learn more of the history of GPS-based time. I received it on June 22, and just 16 days later a similar GPS time server took down Australia's cell service for 12 hours! Over the past couple weeks, I've 'restomodded' this device with a Raspberry Pi, to build a stratum 1 NTP Time server, which I'd like to eventually add to the NTP Pool.

How it works

  • I found a way to drop in a Pi 5 and GNSS HAT, display the time and GPS status on the built-in 16x2 LCD, show the status on the bicolor LED, and make this box useful again.

Details worth keeping

I made a short video about it but put off digging into the TrueTime...

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