Orolia Seven Solutions WR-ZEN Series, Руководство пользователя

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Note: If the device has been shipped with the holdover option, this timing
source will be, by default, configured as the last timing source inde-
pendently of the preset.
5.2.1 Presets
5.2.1.1 WR Slave @ wr0 (BC) [default]
The primary timing source is provided using WR protocol through interface wr0.
The other (wr1) is configured as WR master.
This is the default preset as it is the standard/legacy configuration of most of the WR
devices. This is the simplest Boundary Clock behavior where the device is disciplined by a
single reference and forward its timing to the down layers through all the other ports.
5.2.1.2 External Atomic Clock (GM)
The primary timing source is provided using an external atomic clock reference
through the front-panel 10 MHz and 1PPS inputs (Grand-Master).
All timing ports (i.e., wr0-wr15) are configured as WR masters.
Clock accuracy is announced below or equal to 25 nanoseconds.
Alignment of PPS_in VS PPS_out must be done manually (within picoseconds)
PPS only needed at startup
It is recommended to use this preset when the device is configured to be the Grand-
Master in the timing network and is disciplined using an Atomic Clock as external ref-
erence.
Here, Atomic Clocks means that a very stable oscillator based on hyperfine transition (e.g,
Caesium) that provides very low daily uncertainties (e.g., 1 ns/day) is combined with a
GNSS receiver to remove its slow drift using averaging methods. For telecom, this com-
bination is also known as ePRTC and typically provides a UTC representation accurate
within 10 ns or less. Moreover, in order to guarantee the best timing performance (phase
noise & determinism) the automatic alignment of the PPS output onto the PPS input has
been disabled.
5.2 General Timing Management
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WR-Z16 User Manual Rev. v3.4 49