Example Code

Time Domain Reflectometry

Products and Environment

This section reflects the products and operating system used to create the example.

To download NI software, including the products shown below, visit ni.com/downloads.

    Hardware

  • Modular Instrumentation

    Software

  • LabVIEW

    Driver

  • Other

Code and Documents

Attachment

Overview
In this example, an implementation of Time Domain Reflectometry (TDR) is shown. A NI Arbitrary Waveform Generator and NI Digitizer are used. The application measures the distance between the origin of the sent signal and the first impedance change in a coaxial cable (open or short termination condition).

 
Description
The IVI Time-domain reflectometry or TDR is a measurement technique used to determine the characteristics of electrical lines by observing reflected waveforms. Time-domain transmissometry (TDT) is an analogous technique that measures the transmitted (rather than reflected) impulse. Together, they provide a powerful means of analysing electrical or optical transmission media such as coaxial cable and optical fiber. Hardware is necessary for this application.

 

Requirements

Software:

  1. LabVIEW 2012 (or compatible)
  2. NI-FGEN,
  3. NI-SCOPE

Hardware:

  1. NI PXI-1042Q
  2. NI PXI-8196
  3. NI PXI-5421
  4. NI PXI-5142
  5. BNC T
  6. SMB112 (Double Shielded SMB to BNC Male Coax Cable)
  7. Coaxial Cable (at least 4 meters)

 
Steps to Implement or Execute Code

  1. Open Measurement & Automation Explorer (MAX).
  2. Make sure that in MAX, NI PXI-5421 is named as “Dev1”, and the NI PXI-5142 is named as “Dev 2”.
  3. Open the “TDR DEMO.lvproj”. Then, double click on Cable Length Meter (MAIN).vi.
  4. If it´s necessary, modify the Filter Parameters and/or TDR Parameters. After that, Run the application.
  5. Check the results. The estimated cable length is shown. In addition, other results are included. The TDR ORIGINAL SIGNAL tab presents the raw signal in the coaxial cable. The TDR FILTERED SIGNAL tab shows this signal after a band pass filter is applied. Finally, the TDR NON NEGATIVE SIGNAL tab presents two parabolas used to estimate the distance to the cable termination (or cable length).

 

Additional Information or References
 VI Snippet

 Time Domain Reflectometry 2012 NIVerified.png

 

 **This document has been updated to meet the current required format for the NI Code Exchange.**

Example code from the Example Code Exchange in the NI Community is licensed with the MIT license.

Comments
shazni
Member
Member
on

Hi Josevolquez

I'm currently doing the TDR measurement using the module made by you. From the folder i cannot found the TDR Demo Script.pdf. Can you help to povide  pdf file