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, and offset so you do not mistake switch 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/school → 1231; edge stamp + hardware time I/O → 4096; plant multi-port / dual supply → 8640.
How to choose: SY-1231 vs 4096 vs 8640
Match by application: hospital/school/cabinet → 1231; edge half-width 1U stamp+OCXO+hardware time I/O → 4096; plant multi-port / dual supply → 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.
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Security subnets: SY-1231 first. Coming 4096 only if IRIG is specified.
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.
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Wire and accept per channel. The 1231 has no IRIG.
Cabinet timing: how NTP, Modbus, and 1PPS split
IPCs use NTP, PLCs use Modbus millisecond calendars, scopes see 1PPS—never one shared figure.
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Hospital weak-current: SY-1231. Clinical hosts use NTP; infusion pumps and ventilators typically enter via a time-synchronized gateway.
Why a hospital needs cabinet NTP: six must-haves
Mismatched HIS/LIS/PACS report times are the first hospital NTP driver. Monitors, connected devices, OR records, facilities, and accreditation/MLPS need one inspectable source.
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Production trace: SY-1231. NTP/SNTP on UDP 123; otherwise Modbus millisecond calendar.
Why a production line needs cabinet NTP: five must-haves
Mis-ordered PLC alarms, broken SCADA joins, wrong shift cuts, MES mismatch, and interval-energy drift are the real cabinet-NTP jobs—not a nanosecond slogan.
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Schools: SY-1231 first. Labs that mandate IRIG → coming 4096.
School campus NTP: local GNSS vs public pool
When exams, one-card, and campus security must be auditable, put GNSS NTP in the network room—do not rely on a public pool alone.
Still unsure on scenario or model? Read the selection note or ask us.