Reading
Guides
Each card leads with a decision line, then the full note. Standard protocol names only—no third-party proprietary docs.
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Fix sky view and cable loss before chasing lock or accuracy.
GNSS antenna installation for NTP time servers
Sky view, cable loss, and surge protection—the three steps that decide GNSS lock stability for a cabinet NTP server.
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Prove UDP 123 + LOCK first, then accept stratum/offset on the NIC.
How to verify NTP stratum and offset on a LAN
Check reachability, LOCK, stratum/offset, then size clients with guaranteed throughput and η×R/f_poll (η≈0.8–0.9)—do not mistake switch or overload issues for a bad time server.
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Write 1PPS / PULSE / IRIG / Modbus / NTP per channel—never mix figures.
NTP vs 1PPS vs PULSE vs IRIG-B accuracy by channel
1PPS, PULSE, IRIG-B, Modbus, and NTP are different channels—mixing them in RFQs causes acceptance disputes.
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Shipping cabinet/hospital → SY-1231; edge stamp + hardware time I/O → SY-4096; plant multi-port / dual supply → SY-8640.
How to choose: SY-1231 vs SY-4096 vs SY-8640
Match by application: hospital/cabinet → SY-1231; edge half-width 1U stamp+OCXO+hardware time I/O → SY-4096; plant multi-port / dual supply → SY-8640.
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Need auditable on-prem time? Choose a local GNSS server.
Public NTP pool vs local GNSS time server
Office PCs and auditable cabinet timing are different jobs. Firewalls, audit needs, and I/O decide if you need a local GNSS server.
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If NTP fails, check firewall allow for UDP 123 first.
Firewall UDP 123 checklist when NTP clients will not sync
Many “timing failures” are network policy, not GNSS. Verify UDP 123 and ACLs before swapping antennas.
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On GNSS loss, judge holdover and alarms—not unlocked accuracy.
What holdover means when GNSS drops for a short time
After unlock, time drifts. Drift depends on the oscillator and outage length—do not promise unlock-period accuracy with lock-state figures.
Heshi — Clock analysis & SN format check (local tool)
Still unsure on scenario or model? Read the selection note or ask us.