Time and Frequency Distribution
PTP/White Rabbit Time Distribution with 1 PPS Fiber Fan-Out
Distribution network that delivers the master 10 MHz reference and 1 PPS time tick from the central USO/atomic clock to every Ark subsystem via dedicated coax and fiber links, with PTP (IEEE 1588-2019) and White Rabbit High Accuracy profiles for sub-ns synchronization where required.
Purpose
Ensure every subsystem operates on a consistent, low-jitter time and frequency reference for coherent communications, distributed measurements, transaction ordering, and forensic event correlation across 100 years.
Context
Downstream of L3-COM-TIME-USOC (master source); feeds every subsystem requiring time tagging (CDH, ROB, CRY, GEN, etc.). Uses passive splitters/buffers for short runs and active PTP grandmasters for long runs and across redundant paths.
Principles
- ▸10 MHz sine wave distribution via low-loss coax (or fiber for long runs) maintains phase coherence with proper impedance matching
- ▸1 PPS distribution uses a sharp electrical pulse aligned to UTC second; ground stations and onboard subsystems align edge to picosecond if needed
- ▸IEEE 1588-2008/2019 PTP uses two-way message exchange to measure asymmetric link delay; achievable sync ~100 ns over Ethernet, ~1 ns with hardware timestamping
- ▸White Rabbit HA profile (IEEE 1588-2019) combines PTP with Synchronous Ethernet (SyncE) and dedicated hardware to achieve sub-nanosecond sync over fiber
- ▸Distribution amplifiers (DAs) buffer the reference for many fan-outs; jitter and phase noise are conserved at each branch
- ▸Bidirectional fiber links cancel asymmetric delays for high-accuracy PTP — important for distributed RF and scientific measurements
Typical implementations
- ▸Symmetricom/Microchip SyncServer distribution amplifiers (terrestrial reference)
- ▸Spectracom 9489 PTP grandmaster (industrial PTP)
- ▸Safran Navigation & Timing White Rabbit solutions
- ▸CERN White Rabbit Switch — open hardware, sub-ns synchronization across LHC
- ▸Spacecraft 1553B time codes — heritage low-precision time distribution
- ▸ISS multi-board time distribution via dedicated coax to each rack
Lunar considerations
- ▸Long cable runs across Ark modules require active distribution to overcome ~3 dB/km coax loss
- ▸Thermal gradients along cables cause phase shifts; bidirectional fiber compensates
- ▸Lunar dust on connectors degrades RF performance; hermetic connectors with replaceable interface required
- ▸Radiation environment requires distribution amplifiers to be rad-hard or shielded
- ▸PTP over wireless (mesh) is limited to ~1 µs by RF channel asymmetry — sufficient for most lunar surface needs
Specifications
Functional
| primary function | Distribute master 10 MHz and 1 PPS to all consuming subsystems with low jitter |
| inputs | 10 MHz reference and 1 PPS from L3-COM-TIME-USOC, Power from L1-PDM |
| outputs | Fan-out 10 MHz signals (up to 32 channels), Fan-out 1 PPS signals (up to 32 channels), PTP messages over data networks (L3-CDH-BUS), Health and link quality telemetry |
| channels min | 16 |
| channels max | 32 |
| phase noise dbc hz at 1khz | -150 |
| additional jitter ps rms | 5 |
| ptp sync accuracy ns | 100 |
| white rabbit sync accuracy ns sub | 1 |
| supported standards | IEEE 1588-2019, SyncE, IRIG-B, CCSDS Time Code Format |
Physical
| mass kg | 3.5 |
| dimensions | 300 × 200 × 100 mm rack-mount enclosure |
| materials | Aluminum enclosure with EMI gasketing, Rad-tolerant op-amps and buffers, Single-mode fiber for long runs, RG-393 low-loss coax for short runs (vacuum-rated FEP jacket) |
| operating temperature c | -40, 70 |
| radiation tid krad | 50 |
Operational
| power consumption w | 15 |
| thermal range c | -40, 70 |
| lifetime years | 25 |
| mtbf hours | 200000 |
Interfaces
Provides
- 10 MHz, 1 PPS, PTP messages
- 10 MHz reference for transponder
- 10 MHz / time tick for mesh nodes
- Master timestamp source for mesh sync
Requires
- 10 MHz reference and 1 PPS
- 28 V supply, ~15 W
- Network medium for PTP messages
Cite this entry
Lunar Ark Codex. "Time and Frequency Distribution" (L3-COM-TIME-DIST). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-COM-TIME-DIST
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.