Time Card mini adds Pi, GPS, and OCXO to your PC (www.jeffgeerling.com)
from tedu to tech on 27 Jul 2023 20:01

This build centers around the Time Card mini. Typically you'd install this PCI Express card inside another computer, but in my case, I just wanted to power the board in a semi-portable way, and so I plugged it into a CM4 IO Board. The Time Card mini is a PCIe-based carrier board for the Raspberry Pi Compute Module 4, and by itself, it allows you to install a CM4 into a PC, and access the CM4's serial console via PCIe.

The OCXO isn't for baking cookies, though, it's a special highly-accurate oscillator. Much more accurate than the tiny little quartz crystals used in itty-bitty oscillators you'll find on practically every computing device, ever. Quartz crystals are pretty accurate, but under normal conditions, they can drift as the temperature changes. OCXOs heat up the crystal inside to something like 100°C, and the stable high temperature makes it way more stable. In the case of the SiTime, accurate within 5 ppb of a true second.


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