Masters of Time: EPIC Pulse Delay Generator

Atomic clocks are the most precise way of measuring time, but cannot necessarily be included in your system. However, in many experiments, timing precision is of utmost importance. How can we implement precise timing without an atomic clock and without external reference (e.g., GPS)? Luckily, in many experiments, only relative timing precision is needed which makes this easier, but still challenging. As part of this Capstone project, you will design and build a pulse delay generator, to create pulse/trigger signals, and fully characterize its behavior. Your performance goal is to build a pulse delay generator with high resolution (1 ns), high accuracy even for long delays (milliseconds), and very low RMS jitter (<100 ps) for the generated pulses. In addition, some additional features must be investigated and implemented, to achieve the desired functionality.

Objectives


Deliverable is a working pulse delay generator (PDG)

  • Circuit (KiCAD) and firmware developed by you
    • PDG accepts external trigger with variable input voltage range and adjustable impedance
    • PDG accepts optional external timing reference from OCXO (or Rubidium time base), otherwise uses an
      internal clock source on its PCB
    • PDG can create at least 2 single-ended triggers/pulses and 1 differential trigger/pulse
    • PDG has variable delay insertion for pass-thru of external trigger; and variable delay for internally generated triggers
    • PDG has high resolution, high accuracy, and very low RMS jitter for generated triggers
  • Python API for PC-side to automate pulse delay generator (also important for automated testing of what you are building)
  • A characterization report of the timing accuracy and jitter, as needed to prove proper functionality of your PDG
  • 3D-printed or Hammond enclosure
  • (somewhat optional) Jupyter notebook GUI for convenience

The goal of this project is to create true impact, by not just building “a PDG” but by building the most EPIC PDG and release it under suitable open-source/open-hardware licensing terms. However, due to negative experience with students from a previous Capstone project, I have to add the following:

All developments and deliverables will be under exclusive license of the faculty advisor. In other words: all deliverables as listed here are owned by the faculty advisor and must actually be delivered to the faculty advisor for successful completion of the Capstone project. Do not apply to this project unless you agree to these terms. The main intention of this project is to develop an open-source and open-hardware product that will benefit the greater scientific community. At some point, we will want to release this under an open-source license. I (the faculty advisor) cannot choose the licensing terms unless I own (from an intellectual property point of view) the development. The concept/ideas for the development are provided by me.

Motivations


Many lab instruments and electronic devices use standard crystal oscillators, but their long-term stability is quite limited, which can impact the accuracy of long-term measurements (hours or days). This leads to low quality data and often prevents a successful analysis of the resulting measurement data. In the RF domain, a common solution is to use a GPSDO, i.e., a time base that references the time provided by the GPS system. This provides an absolute time reference (think of: everyone knows which second of the day it is to achieve absolute frequency accuracy), but requires continuous adjustment of the time reference, often resulting in jumps that are contrary to robust, long-term measurements. Instead, what we want, is to use a calibrated Oven Controlled Oscillator (OCXO) as – optional – timing reference for our pulse delay generator. OCXOs provide continuous clocking and are an excellent choice for relative timing stability over longer periods of time (hours to days). However, a stable timing reference is not the only parameter that determines good pulse/trigger/delay behavior. Other aspects are: signal rise/fall time, shape of rising/falling edge, interconnect quality and termination of the I/O, etc. After doing this project, you will know a lot more about time!

Qualifications


Minimum Qualifications:
  • Basic circuit knowledge and previous CAD
    experience (KiCAD)
  • Basic understanding of time references
    (VCXO, TCXO, OCXO, GPSDO)
  • Familiarity with an embedded programming
    platform (microcontroller or FPGA)
  • Knowledge of Python/Jupyter
  • Acceptance of the license terms as listed above.

Preferred Qualifications:

In addition to minimum qualifications:

  • Previous experience with characterization of high-speed digital I/O
  • Strong experience with embedded systems development (microcontroller or FPGA)


Details


Project Partner:

Vincent Immler

NDA/IPA:

No Agreement Required

Number Groups:

1

Project Status:

Accepting Applicants

Keywords:
Embedded SystemsMicrocontrollersKiCAD
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