Time Card: an open source PCIe GNSS+atomic time reference
Time Card is a critical part of a PTP enabled network providing accurate time via GNSS while maintaining accuracy in case of GNSS failure via a high stability (and holdover) oscillator such as an atomic clock.
Existing products in the market are often closed sourced and are far from having sufficient features. The Time Card project presents an open source solution via a PCIe card.
GNSS requires “clear sky” to function properly. Moreover there were several historical events of a short term time jumps by some GNSS constellations. Because of reliability and in combination with the security concerns an additional holdover should be performed by high quality XO. An example could be AC, OCXO, TCXO etc. In order to perform sustainable operation we recommend to use an AC with a holdover ± 1us or HQ OCXO with a holdover ± 22 µs.
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