ET Pathfinder Timing

Project description

This wiki page contains information about the Einstein Telescope Pathfinder timing system.
A prototype system for Virgo and ET Pathfinder evaluation is built based on SPEC7 and an external Low Phase Noise oscillator. The SPEC7 connects to a Grand-Master White Rabbit timing source. SPEC7 creates a copy (TIA) of the Grand Master absolute time and uses this to generate an IRIG-B signal. The phase of the 125 MHz WR clock output (WR Clk Out: J20/J21) is phase aligned with the Grand Master.

Figure 1 shows a picture of the Virgo Demonstrator WR-node front panel.

Figure 1: Virgo Demonstrator WR-node front panel.

Both SPEC7 and the Low Phase Noise oscillator Printed Circuit Board are connected to a Timing Main Board that interfaces the 10/100 MHz Clock and IRIG-B signals to sixteen RJ45 connectors according to the standard that is currently used on the DAQ-boxes at Virgo. By doing so, the complete assembly is a direct drop in replacement for the current timing system at Virgo.

An FMC Breakout is plugged on the SPEC7. This board drives the DAC (LVDS) signals that connect to the DAC/VCXO on the Low Phase Noise oscillator board and feeds the IRIG-B signals to the Timing Main Board.
The Timing Main Board acts as a 16 channel fan-out for the 10 MHz and 100 MHz clock signals that are generated by the Low Phase Noise oscillator PSB and the IRIG-B time signals.

Project information

Figure 2 shows an overview of the system that is composed out of several subsystem Printed Circuit Boards (PCBs).
Each subsystem PCB is bounded by a blue line.
Several connections (shown in green) are made by (RF) cables between the sub-system boards.

Figure 2: Block diagram overview of the timing system. The various subsystem PCBs are bounded by blue lines.

The project consists of several boards: Mechanical information:

Figure 3 shows the interior of the Virgo Demonstrator WR-node.

Figure 3: Virgo Demonstrator WR-node internal.

  • Future developments
  • BabyWR: General purpose small plugable WR node
  • Frequently Asked Questions

Other info (not directly related to timing)


General questions about project


Date Event
29-09-2020 Initial Meeting with LAPP.
17-03-2021 Start working on project. Collecting main specifications.
26-04-2021 FMCBreakout_extended ready for production.
15-10-2021 100 MHz In The Loop ready for production.
18-10-2021 Start layout Timing Main Board.
09-02-2022 Morion Oscillators and 100MHzInTheLoop Board arrived; added link to future BabyWR page.
01-03-2022 Timing Main Board arrived.
10-06-2022 Added pictures.

26 February 2024

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