Selection
Security NVR timing: cabinet NTP vs OCXO/IRIG
Cameras and access usually need one LAN timestamp. Upgrade only when the recorder specifies IRIG time code.
Updated 2026-08-22
Decision
Security subnets: SY-1231 first. Coming 4096 only if IRIG is specified.
Notes
NVR search and access-event correlation need a shared calendar, not a hardware second edge. Cabinet GNSS NTP (SY-1231) keeps the reference in the weak-current room.
Do not default to OCXO. Prove antenna LOCK and UDP 123 first. Treat short unlock as an alarm—do not accept video timestamps against unlocked accuracy.
Choose coming SY-4096 only if the matrix/recorder RFQ writes IRIG-B, or the edge cabinet also needs stamped NTP and holdover.
SY-1231 is built for security subnets that do not need IRIG/OCXO/dual NIC; IRIG → 4096. Plan N=R/f_poll (R = 3840 req/s).
Hospital or school security can share the same 1231 as HIS or the network room if the subnet can reach UDP 123.
FAQ
- What is the decision?
- Security subnets: SY-1231 first. Coming 4096 only if IRIG is specified.
- What are the key points?
- Cameras and access usually need one LAN timestamp. Upgrade only when the recorder specifies IRIG time code.