Live Plotting Tool for the TDR01

Introduction

The current tool is a basic live plotting function which communicates with the TDR01 serial interface using pyVISA. The plotting function includes saving traces, storing traces for comparison, and cursor annotations. The TDR01 is a compact, rugged, and cost-effective Time Domain Reflectometer (TDR) with 60ps edges (90-10%). 16 bit timing precision allows for single picosecond resolution.

Basic Commands

The device is a SCPI compliant interface (std V1999.0 4.2.1) over a 115.2k baud 8n1 3.3V UART.

• *IDN:
• TRACE: Starts a data trace and returns an NPOINTS long CSV of 12 bit values terminated with a new line (standard SCPI). If averaging is used then each point is the sum of the repeated runs. The scale factor to volts is then voltage = raw_value × (3.6 V) / (AVG × 4096)).
• RXDAC?: Returns the dac settings of each point on the timing ramp. The peak ramp voltage is configurable with DA and DB
• NPOINTS: Number of points in a trace.
• AVG: Number of averages per point
• RES: Spacing between consecutive points in integer picoseconds
• ISTART: Starting index of the trace. The start time is RESxISTART.
• PULSES: Number of integration points per measurement.
• RAMP: Choose the ramp time constant (1: Fast, 2: Slow)

Installation & Use

The live trace plot is a python package in a TKinter environment. The tool has been tested on both Windows 11 and Ubuntu 24.04, with Ubuntu as the primary development platform.

Ubuntu Dependencies

apt-get update
apt-get install -y \
    python3-tk \
    tk \
    x11-utils \
    libx11-6 \
    libx11-xcb1 \
    libxcb1 \
    libxext6 \
    libxrender1 \
    libxrandr2 \
    libxi6

Use

monitor_tdr --device /dev/ttyUSB0

monitor_tdr --help

Usage: monitor_tdr [OPTIONS]

Options:
  --sleep FLOAT        Sleep time in between traces
  --m FLOAT
  --rc FLOAT
  --start_time FLOAT
  --ramp_mode INTEGER
  --spacing INTEGER
  --maxtime INTEGER
  --device TEXT
  --help               Show this message and exit.

Precompiled Binaries

Precompiled binaries are available under here.

dist/monitor_tdr --device /dev/ttyUSB0

Building Binaries

First install in a clean virtual environment and run:

pyinstaller pyinstaller.spec

Installation From Source

If installing locally then a virtual environment or anaconda should be used.

pip install .